My husband and I live in the southern Chicago suburbs. Humidity does get quite high in the Chicagoland area. I am extremely sensitive to humidity and would like to keep it as close to 30% as possible.

To save gas/electric costs, on April 24, 2008, we replaced a functioning Carrier system (I'm SO sorry that we did) with an 80% efficiency American Standard Freedom 100,000 BTW 80%, 2 stage variable speed furnace with matching coil. We also installed an American Standard Allegiance R-410A 3 1/2 ton 14 SEER air conditioner. We also installed an Air Bear media filter system. They also installed a new Honeywell Programmable thermostat.

From day one, I felt that the humidity was too high in the house. I have bad allergies and often keep the house closed up just to keep the humidity low and the allergens out. The Owner/Installer told me to hang in there because an AC will not efficiently remove humidity unless it can run for a good long while. That made sense to me so I waited until it got hotter here in Chicago. The humidity levels were bearable while the heat was still running although I did turn off our humidifier because I didn't want to add any more humidity to the heating system.

I've had the house closed up for about a week and a half straight now. I bought a hygrometer and the humidity inside will not go below 55-60% with the thermostat set at 71 or 72 degrees which is my normal setting. I didn't do the salt test on the hygromter but I did put it outside for about 6 hours and monitored the humidity reading against a close local weather station. So I feel I know the differential readings on my hygrometer.

The company came back out last Thursday, checked freon and all installation items and says everything is fine. They even talked to American Standard and got some suggestions. I called the owner of the company that installed the system on Friday to tell him that what they had done had not helped. On Saturday morning, he told us to turn the thermostat to 65 degrees and let it run to get the humidity down. We did that and the humidity lowered from about 60% to 45% over the course of about 8 hours. The system ran without stopping the entire time. The temperature never went below 71 degrees even though it was only 83 degrees out yesterday. Once it got about 7:00 p.m. it finally went down to 69 degrees. As soon as we turned the thermostat back up to 70 degrees, within an hour, the humidity level in the house went back up to about 53%.

On the day before, I noticed that the air, set at 72 degrees on an 80 degree day would come on for 10 minutes and be off for only 10 minutes. Is this normal or is this what is called short cycling? If so... what does that mean?

I am horribly uncomfortable. The installer acts as if this is an OK humidity level. As I said before, we had an old Carrier AC unit from around 1991 that was able to cool properly and keep the humidity at or below the 30% level. Nothing else changed in the house. This installer has been doing our maintenance on the old system for about 8 years so he knows that we never had an AC issues. He's coming back out on Monday but says he's stumped and has never seen this problem in 37 years. Do we have a lemon AC?

We bought the American Standard extended full system warranty for 5 years. Can we hope for any help from them? Should we call another AC installer to look at it?

Help... my husband and I are not mechanically inclined at all nor do we have anyone else who can help us.

I am not answering the question, but I have the same problem in Ohio. The humidity hovers around 58% and the old unit cooled the house better than this one. We just had the unit installed in March. I love how quiet the unit is, but I though we would be able to leave it on 72 and save costs on running it. We have it on 70 and the humidity makes it very uncomfortable. I am calling the installed tomorrow.

I just wondered if you received an answer to your problem because we have the identical problem here in Ohio.

You should have about a 20 degree difference from the return air to the supply air after the A/C unit runs for 5 minutes. This is called TD or total differential.

Have the company set up the variable speed blower to run slower and longer on start up. The slower air movement will remove more moisture from the air much faster. Once the moisture has been removed the unit can concentrate more on the temperature drop in the home.

I am in a very high humidity location myself. A three of my A/C units run water like you turned on a faucet for the first 15 to 30 minutes of operation then the blower ramps up to satisfy the cooling aspect of the home.

One thing to remember. The newer units have less moisture removal capacity especially the ones with the variable speed blower unless the blower unit is set up properly.Most companies just install the unit and walk away with out any adjustments because they feel it is all done at he factory and that is just not true.

The system I have is somewhat elaborate in its control nature but it is always comfortable.

If your A/C company cannot find or fix the problem it might be time to have a more knowledgeable company look over the system.

Thanks SO much for the information HVAC1000! The company is supposed to be coming out today to work on it after they talk to American Standard. The Owner mentioned slowing down the blower as a possibility. He asked me how the blower was and I said it wasn't blowing very hard already.

A couple of more questions for you or anyone else who could help. Does the variable speed blower bring in more outside air than just the plain two stage? I don't want to be constantly having to dehumidify.

Will slowing down the motor make it less cool in here? I'm afraid to have him slow down the blower if it will affect the cooling and/or efficiency.

What should I know about TD? I've never heard of this before and don't understand even what to ask him.

Thanks everyone in advance. Karen from Ohio... I feel your pain.

Thanks SO much for the information HVAC1000! The company is supposed to be coming out today to work on it after they talk to American Standard. The Owner mentioned slowing down the blower as a possibility. He asked me how the blower was and I said it wasn't blowing very hard already.

A couple of more questions for you or anyone else who could help. Does the variable speed blower bring in more outside air than just the plain two stage? I don't want to be constantly having to dehumidify.

Will slowing down the motor make it less cool in here? I'm afraid to have him slow down the blower if it will affect the cooling and/or efficiency.

What should I know about TD? I've never heard of this before and don't understand even what to ask him.

Thanks everyone in advance. Karen from Ohio.....I feel your pain.


Does the variable speed blower bring in more outside air than just the plain two stage?

The blower does not bring in any outside air unless they added a make up air duct and if they did I would like to know why. Also if they did do that then they should have put a damper in it for adjustment or to close off when not wanted. I bet there is no make up air duct attached but you never know.

Will slowing down the motor make it less cool in here? I'm afraid to have him slow down the blower if it will affect the cooling and/or efficiency.

That depends. The first rule is to get rid of the moisture first. You can be comfortable at 80 with very low humidity. After the humidity is lowered then it is time to cool the house down to where you want it. In Ohio humidity removal is more important than cold temperatures since Ohio has a boat load of humidity in the air during the spring,summer,and fall. I live in Ohio so I am well aware of the humidity problems.

What should I know about TD? I've never heard of this before and don't understand even what to ask him.


TD stands for total differential. Under ideal conditions the TD should be 20 but 18 degrees is acceptable.

TD is the total differential between the air that is being sucked into the system and the air being blown out of the system. It is the amount of temperature drop that the A/C coil in the furnace is providing. I hope that this expalins what TD is.

There are many things that can cause the problems you are having. The cure is to have the blower run at low speed to remove the moisture/humidity the ramp up to a higher speed to cool the home. See if they can arrange that for you. Good luck.

Does the variable speed blower bring in more outside air than just the plain two stage?

The blower does not bring in any outside air unless they added a make up air duct and if they did I would like to know why. Also if they did do that then they should have put a damper in it for adjustment or to close off when not wanted. I bet there is no make up air duct attached but you never know.

Will slowing down the motor make it less cool in here? I'm afraid to have him slow down the blower if it will affect the cooling and/or efficiency.

That depends. The first rule is to get rid of the moisture first. You can be comfortable at 80 with very low humidity. After the humidity is lowered then it is time to cool the house down to where you want it. In Ohio humidity removal is more important than cold temperatures since Ohio has a boat load of humidity in the air during the spring,summer,and fall. I live in Ohio so I am well aware of the humidity problems.

What should I know about TD? I've never heard of this before and don't understand even what to ask him.


TD stands for total differential. Under ideal conditions the TD should be 20 but 18 degrees is acceptable.

TD is the total differential between the air that is being sucked into the system and the air being blown out of the system. It is the amount of temperature drop that the A/C coil in the furnace is providing. I hope that this expalins what TD is.

There are many things that can cause the problems you are having. The cure is to have the blower run at low speed to remove the moisture/humidity the ramp up to a higher speed to cool the home. See if they can arrange that for you. Good luck.



I am not a great fan of variable speed motors because of the replacement costs.

I prefer a 3 or 4 speed motor with a relay and humidstat installed. Works better than variable speed.

I am not a great fan of variable speed motors because of the replacement costs.

I prefer a 3 or 4 speed motor with a relay and humidstat installed. Works better than variable speed.

OR this

Owner is here now. He's talked to American Standard and he's installing something to connect "y and o" and slowing down the blower speed to automatically allow for more dehumidification. He says we have great quality equipment.

He says it doesn't feel humid in here to him. According to my Honeywell hygrometer, it's about 59% humidity. If I had my druthers, it wouldn't ever be over 30% in here.

I'll keep you all posted. It's supposed to be cool here in Chicago for the next couple of days so it may be hard for me to test the system changes right away.

Hello Everyone:

A big thanks to hvac1000 for all the suggestions. They are over my head, but I am routing the information hopefully to the right person. I was wrong about the unit that we have. It is a American Standard (Allegiance 14), 95% efficient, variable speed, dual stage, 100,000 BTU furnace with a 14 Seer, 3 ton R-410A system, A/C unit; we also installed an American Std. Aprilaire model 700 powered humidifier for the furnace and the American Std. Accuclean air filter.

Our humidity has consistently been 58-60% since we started using the air. It should be 30-35% I think. It just really sounds like we have the same problem. I reported the information to our installer and hope to hear from him this week. The office said that he might have to call American Standard tech support, which is what CassieandCameo's people did initially (to no avail).

There is absolutely no doubt in my mind that we have the same problem. AC should lower the humidity.. . Our old clunker did a better job. This must either be defective or it isn't set right. Hvac1000 certainly knows his/her stuff!

American Standard makes good equipment. Actually all manufactures make good equipment or they would not be in business for long. The problem is always in the install or adjustments and settings. These items are what separate a quality company from all the run of the mill companies out there.

For many years in this area we were known as the company that could take a sows ear and turn it into a silk purse. It is all in the install,settings, and adjustments. Never in the equipment unless they ask it to do something it is not designed to do.
I would say that most if not all people who help answer questions here are of good report and knowledgeable. In fact there is probably 500 years experience if you total up all the HVAC time of all the helpers. That is a lot of time in the trenches for a HVAC help board to have on tap and if one person here does not know the answer the others will.

I wish you both good luck in dealing with your problems. Post back when they find the solutions to your problems so we can also add that to the old memory banks and to help future homeowners.

One more thing to add to all of the great answers you have already received. Is it possible the contractor oversized your system? What happens when a system is oversized is that it tends to cool so rapidly that it doesn't have time to remove the humidity before it cycles off. Sorry if I missed that in the other posts, but I did not see that explanation offered.

I'll definitely report back with the results when I can test the system. Temps dropped her in Chicago on Monday after the Owner left so we haven't had the air on since then.

It's great to know that it's probably not the equipment HVAC 1000. It makes me feel that all of this tinkering is not just to shut me up!

Missouri bound... best I can tell we aren't oversized or if we are it's just a tad. We had a 3.5 ton system and that's what the new one is. We have 2000-2500 square feet. The 2500 figure includes the basement. If his tinkering doesn't work, I'm going to pursue the size issue.

There was one late afternoon when the temperature outside was 80 degrees. We had the thermostat set to 72. It would come on for 10 minutes; reach it's temperature and then go off for 10 minutes. It cycled on and off in 10 minute increments for the whole hour that I clocked it. I asked the Owner/Installer about this and he said it wasn't short cycling.

Hmmmmm... ok... for now.

Thanks everyone. Good Luck Ohio!

Send me the brand and model number of the new thermostat they put in when you got your new equipment. I want to look it up to see the factory set points.

My husband and I live in the southern Chicago suburbs. Humidity does get quite high in the Chicagoland area. I am extremely sensitive to humidity and would like to keep it as close to 30% as possible.

To save gas/electric costs, on April 24, 2008, we replaced a functioning Carrier system (I'm SO sorry that we did) with an 80% efficiency American Standard Freedom 100,000 BTW 80%, 2 stage variable speed furnace with matching coil. We also installed an American Standard Allegiance R-410A 3 1/2 ton 14 SEER air conditioner. We also installed an Air Bear media filter system. They also installed a new Honeywell Programmable thermostat.

From day one, I felt that the humidity was too high in the house. I have bad allergies and often keep the house closed up just to keep the humidity low and the allergens out. The Owner/Installer told me to hang in there because an AC will not efficiently remove humidity unless it can run for a good long while. That made sense to me so I waited until it got hotter here in Chicago. The humidity levels were bearable while the heat was still running although I did turn off our humidifier because I didn't want to add any more humidity to the heating system.

I've had the house closed up for about a week and a half straight now. I bought a hygrometer and the humidity inside will not go below 55-60% with the thermostat set at 71 or 72 degrees which is my normal setting. I didn't do the salt test on the hygromter but I did put it outside for about 6 hours and monitored the humidity reading against a close local weather station. So I feel I know the differential readings on my hygrometer.

The company came back out last Thursday, checked freon and all installation items and says everything is fine. They even talked to American Standard and got some suggestions. I called the owner of the company that installed the system on Friday to tell him that what they had done had not helped. On Saturday morning, he told us to turn the thermostat to 65 degrees and let it run to get the humidity down. We did that and the humidity lowered from about 60% to 45% over the course of about 8 hours. The system ran without stopping the entire time. The temperature never went below 71 degrees even though it was only 83 degrees out yesterday. Once it got about 7:00 p.m., it finally went down to 69 degrees. As soon as we turned the thermostat back up to 70 degrees, within an hour, the humidity level in the house went back up to about 53%.

On the day before, I noticed that the air, set at 72 degrees on an 80 degree day would come on for 10 minutes and be off for only 10 minutes. Is this normal or is this what is called short cycling? If so....what does that mean?

I am horribly uncomfortable. The installer acts as if this is an ok humidity level. As I said before, we had an old Carrier AC unit from around 1991 that was able to cool properly and keep the humidity at or below the 30% level. Nothing else changed in the house. This installer has been doing our maintenance on the old system for about 8 years so he knows that we never had an AC issues. He's coming back out on Monday but says he's stumped and has never seen this problem in 37 years. Do we have a lemon AC?

We bought the American Standard extended full system warranty for 5 years. Can we hope for any help from them? Should we call another AC installer to look at it?

Help.....my husband and I are not mechanically inclined at all nor do we have anyone else who can help us.
.: R22 vs R410A (http://aircontalk.blogspot.com/2008/04/r22-vs-r410a.html)

I am not answering the question, but I have the exact same problem in Ohio. The humidity hovers around 58% and the old unit cooled the house better than this one. We just had the unit installed in March. I love how quiet the unit is, but I though we would be able to leave it on 72 and save costs on running it. We have it on 70 and the humidity makes it very uncomfortable. I am calling the installed tomorrow.

I just wondered if you received an answer to your problem because we have the identical problem here in Ohio.
.: R22 vs R410A (http://aircontalk.blogspot.com/2008/04/r22-vs-r410a.html)

My husband and I live in the southern Chicago suburbs. Humidity does get quite high in the Chicagoland area. I am extremely sensitive to humidity and would like to keep it as close to 30% as possible.

To save gas/electric costs, on April 24, 2008, we replaced a functioning Carrier system (I'm SO sorry that we did) with an 80% efficiency American Standard Freedom 100,000 BTW 80%, 2 stage variable speed furnace with matching coil. We also installed an American Standard Allegiance R-410A 3 1/2 ton 14 SEER air conditioner. We also installed an Air Bear media filter system. They also installed a new Honeywell Programmable thermostat.

From day one, I felt that the humidity was too high in the house. I have bad allergies and often keep the house closed up just to keep the humidity low and the allergens out. The Owner/Installer told me to hang in there because an AC will not efficiently remove humidity unless it can run for a good long while. That made sense to me so I waited until it got hotter here in Chicago. The humidity levels were bearable while the heat was still running although I did turn off our humidifier because I didn't want to add any more humidity to the heating system.

I've had the house closed up for about a week and a half straight now. I bought a hygrometer and the humidity inside will not go below 55-60% with the thermostat set at 71 or 72 degrees which is my normal setting. I didn't do the salt test on the hygromter but I did put it outside for about 6 hours and monitored the humidity reading against a close local weather station. So I feel I know the differential readings on my hygrometer.

The company came back out last Thursday, checked freon and all installation items and says everything is fine. They even talked to American Standard and got some suggestions. I called the owner of the company that installed the system on Friday to tell him that what they had done had not helped. On Saturday morning, he told us to turn the thermostat to 65 degrees and let it run to get the humidity down. We did that and the humidity lowered from about 60% to 45% over the course of about 8 hours. The system ran without stopping the entire time. The temperature never went below 71 degrees even though it was only 83 degrees out yesterday. Once it got about 7:00 p.m., it finally went down to 69 degrees. As soon as we turned the thermostat back up to 70 degrees, within an hour, the humidity level in the house went back up to about 53%.

On the day before, I noticed that the air, set at 72 degrees on an 80 degree day would come on for 10 minutes and be off for only 10 minutes. Is this normal or is this what is called short cycling? If so....what does that mean?

I am horribly uncomfortable. The installer acts as if this is an ok humidity level. As I said before, we had an old Carrier AC unit from around 1991 that was able to cool properly and keep the humidity at or below the 30% level. Nothing else changed in the house. This installer has been doing our maintenance on the old system for about 8 years so he knows that we never had an AC issues. He's coming back out on Monday but says he's stumped and has never seen this problem in 37 years. Do we have a lemon AC?

We bought the American Standard extended full system warranty for 5 years. Can we hope for any help from them? Should we call another AC installer to look at it?

Help.....my husband and I are not mechanically inclined at all nor do we have anyone else who can help us.
The Truth About Puron Freon 12 Refrigerant 22 Scam (http://www.toad.net/~jsmeenen/freon.html)

The Truth About Puron Freon 12 Refrigerant 22 Scam (http://www.toad.net/~jsmeenen/freon.html)

I'm sorry to hear about your problems. If your old unit did the job and the new one does not, there is some problem either with installation or equipment. Although you need to have the hvac problem corrected, would you consider purchasing a dehumidifier to make you more comfortable? I'm not suggesting you just live with the problem, but a dehumidifier may make you more comfortable until the problem is resolved.

I just took a peek here and I'll add my $0.02 worth.

1. Temperature differential needs to be measured. It's a measure of the overall health of the AC unit. The amount of difference achieveable is dependent on incoming and outgoing air and the RH of the incoming air.

2. Is the humidifier operating? If it is, your shooting yourself in the foot.

3. Do you have selectable hot/cold air returns? These can make a big difference. Open near ceiling returns in summer and open lower ones in the winter.

4. tstsat's can play games to reduce humidity such as this one: Buy Honeywell VisionPro 8000 Programmable MultiStage Thermostat with Dehumidification | Honeywell TH8321U1006 (http://www.prothermostats.com/product.php?p=honeywell_th8321u1006&product=100927)
In essence, it lowers the temperature up to 3 degrees to try to achieve RH.

5. Keeping the air over the evaporator longer by lowering fan speed WILL lower humidity.
hvac100: Like your humidity controller.

6. Carrier's Infinity Control does have a humidity setpoint. It knows a lot about the system like BTU capacity, inside temperature, outside temperature, humidity. It can control both fan speed and run-time.

7. An airconditioner is just that. It cools the air. For true dehumidification you need, what else, a whole house dehumidifier such as: Search | Furnace and Whole House Air Filters from iaqsource.com (http://www.iaqsource.com/search.php?keywords=whole+house+dehumidifier&submit_continue=Go)

A home HVAC system is generally a kludge for comfort. There is a so called "comfort chart" that lists temperature/humidity/summer/winter which effectively shows wha percentage of the population is supposed to be comfortable depending on the above variables.

You don't have "tons" of cooling capacity, nor the ability to heat the air before cooling. I do that all the time in the car. I have AC and heat on at the same time when it's raining to remove moisture and make my feet more comfortable.

You can add ERV's/HRV's or heat recovery ventilators: Energy and Heat Recovery Ventilators (ERV/HRV) (http://www.toolbase.org/Technology-Inventory/HVAC/energy-recovery-ventilators)

You don't have pressure sensors in the building, so waste heating or cooling won't escape so easily.

You have odor control. Separate ventilation, make up air for ventilation. Fire damper control. Odor control can be via charcoal filters. Particulate control via electronic air cleaners and paper elements. Virus control with UV lamps.

House stuff is relatively low tech, but you can have a mechanical room for a home. The trick is wants, needs and cost. Both operating and initial.

The competent engineer/installer makes the difference!

My wife and I also live on the Southside of Chicago and we have had the same high humidity/poor air quality problem for years and everyone thinks we are crazy. Did Doorenbos install your unit? Who did you use to fix the problem?:confused:

Hey Irish! AirEase is the company who installed the unit. They were VERY responsive. After contacting American Standard, they were guided through the adjustments to make in the "dip switches"? Anyhow, the problem has been fixed and the unit is now removing humidity.

If you know Dornbros you must be Southside. AirEase is in Tinley Park. They were very good to us. Never made me feel crazy.

Good Luck.

The cure is to lower your indoor blower speed and let the air get more hang time at the coil. This will cause more drop out in the humidity department and you will be more comfortable.

Another note: If your unit was sized to large or to small this could also be a problem

Interesting.. . We contacted American Standard and were given the name of another AC person in the area. That person told us that the newer units do not eliminate the humidity as well as the old ones. We were told that humidity hovering around 50% is acceptable. The guy told my husband that AC people should not be selling the units without being upfront with customers about how the newer units run differently.

So, we're been living with 48-52% humidity and feel like that is what we have to accept. The guy did come out and adjust the blower speed, but I'm not seeing a real difference. Our humidifier is off.

I still don't believe that we are supposed to just "accept this."

Mine is lower, Karen. It's more in the 33-42% range but then every humidistat is different too. All I know is that it feels comfortable to me now. When my humidistat goes below 40%, it shows a sad face but MY face is happy! I wouldn't be happy at 50% either.

My guy did not just lower the blower, he also changed some switch settings.

Cassieandcameo: Any idea what he switched? I don't think our person really knew what he was doing. Many thanks--it is encouraging that the problem can be fixed. We keep our temperature at 70 degrees. I had thought with the new unit we should be able to set it at 72 and be comfortable---but that is not the case. What temp are you running yours at?

I looked at a good readable copy of a comfort chart. It generally states that most people are comforable between 70 and 75 degrees and Relative Humidity between 30 and 50%. I had a chart with a summer/winter component somewhere.

Don't operate the air conditioning with any windows open. This includes opening bathroom windows when taking a shower or to reduce odors. Yes, this brings in fresh air, but humidity in the air will condense onto the registers that are nearest to the open window. If you must open a window because the bathroom doesn't have an exhaust fan, close it as soon as visible moisture on the walls and mirrors is gone.
Don't run the indoor blower on continuous operation. If you do, any water left on the coil or in the drain pan will re-evaporate when the compressor shuts off. This can raise the relative humidity in the house by 15%.
Don't set the thermostat too low. If you have the temperature in the house too low, you increase the risk of condensation forming on some surface in the house. This could even occur on a hidden surface, such as inside the walls.
When operating exhaust fans, remember that while you're exhausting air and moisture to the outside, you're also bringing air and moisture back in from the outside. Whatever you blow outside will leak back in somewhere else. Don't run your exhaust fans any longer than necessary. This includes bathroom exhaust fans, kitchen exhaust fans, range fans, and clothes dryers. If the air outside has more moisture in it than the air you're exhausting to the outside, you're doing your house more harm than good.
Make sure exhaust fans terminate outside. I've often seen dryer ducts that terminate in the crawlspaces and attics. Many bathroom exhaust fans blow into attics. This can cause tremendous moisture problems in attics and crawlspaces. Your air conditioner cannot handle this kind of problem.
Don't pile ground too high against the house. Water can wick into slab edge, foundation, and crawlspace. Waterproof the edges of the slab or the below-grade foundation walls. Put moisture barriers on top of all foundation piers. Don't let wood contact ground or bare concrete.
Consider installing a dehumidifier in problem areas of your house, basement or crawlspace. Keep in mind that there are whole-house dehumidifiers that can be connected to your air conditioning and heating duct system that will dehumidify your house extremely effectively, thus improving both your air conditioner's performance and your comfort.
Home infiltration from natural building leakage. This includes crack leakage around doors and windows as well as electrical outlets and other building envelope cracks. Plumbing pipes coming up through the floor from a crawlspace can also leak air into the house. This infiltration is mostly wind­ driven. Leaving windows open during cool mornings in the summer has the same effect. Even though the outside air temperature is low, the moisture levels in the outside air can be very high. If the house has a damp crawlspace or basement, water vapor can penetrate through wood floors into the house. Water vapor flows from high concentra­tions to low concentrations, just like heat. This is in addition to air infiltra­tion already described above.
Improperly sized and improp­erly installed air-conditioning sys­tems. Significantly oversized air condi­tioners and heat pumps do not control humidity as well as properly sized units. This is because the indoor coils do not get really cold until after the cooling unit has been running for as long as 15 minutes or more. Oversized units tend to short-cycle: they cool the air quickly, and then shut off.


About R-410

Home - R-410A - Honeywell AZ-20 Refrigerant (http://www51.honeywell.com/sm/410a/)

If a slower blower speed does not help with humidity removal there is something wrong with your system. Call someone else who is more experienced with R-410 and get it fixed. Back bill the original company for the work. If they do not pay take them to small claims court.

NOTE keep all documentation and have it clearly stated what was causing the humidity problem and what was done for the cure.

BEEN there done that for people as a PW (professional witness)

Cassieandcameo or anyone else: specifically, what switches need to be adjusted? We are willing to call your person/company in Chicago for help. As for the suggestions, we are pretty good with the common sense pieces. However, I did not think that we should also have to install a dehumidifier to use concurrently with the AC. We did not need it with our old clunker that we had.. .

I replaced my Honeywell thermostat (mercury type) with a programmable White Rogers thermostat last heating season. I kept it at a constant temperature because when ever I set it back, it needed the aux heat to recover, and that didn't help my electric bill. Now this summer, when I switched to cool, I found that I had a problem similar to yours, unit turns off and on too quickly (in my opinion) and the humidity is always around 50-55
%

So I decided to put my old Honeywell thermostat back on and instantly noticed longer run times, but fewer run times. And now the humidity stays around 36%. At 75 degrees I find this comfortable. If the unit is working as it should, try an inexpensive mercury type thermostat. You lose the programability, but you may get the comfort level you want. At any rate, it worked for me.

There are programmable stats. At least one of the Vision Pro 8000 models (e.g. 8321) has the capability to "dehumidify". What it will do is lower the room temperature up to 3 degrees to attempt to attain the RH setpoint.

In a mechanical stat, the "anticipator" creates the deadband. If the deadband is higher, you get increased cooling and lower humidity. So, there is basis that the machanical stat will work.

Keep it, I agree. But these poor folks have been swamped with ideas, suggestions and 6 weeks later they still are living with the problem. With a $25 thermostat they may be able to solve the problem quickly without making them wade through technical information which they may not comprehend or advice which may only delay them from any results. If this barrage of "ideas" keeps going on, they will be in the heating season and they won't have a humidity problem. Once they determine if it's a thermostat issue, then they could move forward as per your suggestion to a thermostat with humidity control, if they wish.