Hi All:

I have Bryant plus 90 gas furnace and used to have Lenox Mercury thermostat. Heat will kick in for 15~20min after every one hour. Does not follow thermostat. So just change a new Honeywell programmable thermostat, but it is still doing the same.

At the furnace LED indicator blinking 3 quick blink and one solid long one. Per the cause mentioned it in the panel it is for high wind, or improper size of the air intake, Inducer motor problem, etc. But if this is due to these causes why furnace is still kicking in every hour for 15~2o minutes?

Friends, please let us know how should we solve this.
Thanks so much.

Chemia

On the furnace turn off power and disconnect the R and W wires and then turn the furnace power back on then see if it kicks on after waiting a hour or two. This will eliminate the possibility of a shorted thermostat wire. If the furnace still kicks on then we know the thermostat and thermostat wiring is not at fault and the problem lies in the furnace itself..

Hi HAVC 1000:
Thanks for your response. I have done the things you have asked for, about an hour going no sign of furnace to kick in.
What should be done next, please let us know. It is really cold in Michigan.
Your early response will be great help.
Thanks,
Chemia

By the way the LED light is solid red right now after powering back with R & W wire open.
I left them still open and waiting for your response.
Thanks.

Now turn power off and jumper R and W with a jumper wire. Turn power back on. The furnace should come on and stay on. Let it run a 5 minutes to confirm that the furnace is not droping out for any reason. This test will confirm that the unit is operating OK without a having a thermostat controlling it.

HAVC 1000:

Yes, I did jump the R & W with a jumper wire (single thread of a Telephone wire).
1. The Blower fan kicked in first and blowing cold air, and it turned off after 3 minutes.
2. Furnace kicked in and stayed on.
3. After another about 2 minutes Blower fan turn ob again and still blowing hot air.

What should be done next. Red and White wire still kept open.

Thanks again, looking forward to your response.

Chemia.

1. The Blower fan kicked in first and blowing cold air, and it turned off after 3 minutes.
2. Furnace kicked in and stayed on.
3. After another about 2 minutes Blower fan turn ob again and still blowing hot air.
Confusing

When the furnace is turned on with R and W jumpered the small fan for combustion should come on.

Then the burner

Then the blower.

Is it not following this order exactly?

Also post Exact complete model number.

Hi:

It might be turned on as per the sequence you described but not so apart from each other.
Heat is still on so do LED light.

I got the model name from the front panel saying, Bryant Plus 90, Highly Efficient Gas Furnace,

In side furnace side pane it shows the Model number, 350MAV048100 and the serial number is 3899A05652.

Please let me what to do next. Should I have control the furnace by turning on and Off?

Thanks for the help.
We appreciated very much.

Turn it off for now. If it is still running it got to be hot. LOL I am going to look into the model number

Furnace just turned off it self. In the wall monted thermostat reading 61F. Although thermostat set at 70F.
Thanks,

The original complaint was a code 31

The description for code 31 lists the following:
Pressure, draft safeguard, aux-limit switch (when used*),or blocked vent switch(when used)did not close or reopened.
(Downflow only*) If open longer than 5 minutes, inducer shuts off for 15 minutes before retry. Check for:
- Low inducer voltage
- Defective blower motor or capacitor
- Defective pressure switch
- Inadequate combustion air supply
- Disconnected or obstructed pressure tubing
- Proper vent size
- Defective inducer motor
- Restricted vent
- Excessive wind

For now hook the thermostat wire back up in the unit and keep the house warm.

Next

The above description of the code you got from the board seems to offer many possibilitys and when you jump the R and W in the unit the unit works well with no problems you said so here is what I think.

It seems the problem is happening only when the thermostat is connected. In that case it is the thermostat or the wiring for the thermostat that is causing the problem but I never like to rush to judgement when the problem is intermittent. So here is what I suggest

Later today or tomorrow when you have the time get a small switch with wires and use the switch to jumper the R and W wires for testing purposes. The reason for this is to control the furnace from the low voltage control instead of from the 120 volt switch. The reason for this test is that every time you kill the 120 volt power as in turning off the switch that is on the furnace you reset the circuit board and loose any stored signals or blinks also clearing the circuit board by turning off the 120 volt furnace switch is not allowing the furnace to operate as if it has a thermostat hooked up to it. Using a small switch across the R and W wire will allow you to be the thermostat if you know what I mean.

Run the furnace with this setup for 6 hours or so and see if you can tell if the furnace/blower kicks in by itself every 15-20 minutes like it did before. I know this test is a pain in the a$$ but it is much better than the shotgun approach of replacing the thermostat and if that does not work replacing the circuit board and if that does not work etc. You get my idea I am sure.

After you do this post back to this same original thread with the results so we can continue this
diagnosis.

Furnace just turned off it self. In the wall monted thermostat reading 61F. although thermostat set at 70F

Was the jumper on or the thermostat hooked up when the furnace shut off by itself.

Hi:
I just went to close the panel,
1. Turn off the power
2. Insulate the opened Red and White wire plastic tape.
3. Close the inside panel cover,
4. Close the main front panel cover.
5. Turn on the switch,
a) Blower turned on
b) After few 3~4 minutes blower turned off.
c) Another 3~4 minutes later small fan turned on.
d) Gas/furnace never kicked in.

Now all the panel are close, and temperature is going down wall mounted thermostat reads 59F but it is lot colder than the 59.

Any suggestions, please let us know.
Thanks,

I am really trying to understand this. Are you telling me the furnace does not produce heat now at all?

Jump the dag gone R and W connections out again on the furnace then turn the power back on. It should come back on and heat if not then post the number of blinks on the control. NOTE: the blower door must be on or the furnace will not work since there is a blower door safety switch that the door activates.

Hi:

I left the R &W jumped and closed the panel with both of the red and white wire open insulated, so open copper portion.

Now the after an hour furnace came in and ran for close to 20 minutes.

Is this solved the problem if I leave it it like this?

Please let us know.
Thanks,

Forgot to mention that when heat was on LED was solid red now after heat off again,
LED blinking 3 times and 1 time solid.
Thanks,

You need to hook the thermostat wires back up so the thermostat controls the furnace. Discard the jumper since its kob is over. This is as far as I can take you in the repair of your furnace. The code 31 can be many different things but at least we proved the thermostat and wiring for the thermostat are good and the problem is with the furnace. Turn the thermostat on and your unit will probably go back to intermittent operation as before.

You are going to have to call for On Site service since the code 31 is still showing on the circuit board. Sorry but that is all that I can do this evening.

A froze or restricted drain line on the furnace will cause the same symptoms your having.

That is a good thought but there was never a mention of freezing in the furnace area.

With the unit kicking on by itself with the thermostat turned off I am inclined to think circuit board since we eliminated the thermostat/wiring but I feel they would be better off having it checked on site by a local company. Any further testing and I was afraid they might be left without any heat at all till the repair company could arrive.

Attic jobs are the ones with the real freezing problems. Speaking of freezing it sure got cold outside here.

True but if its cold outside the drain on the outside of the house can freeze and cause water to backup and inturn open the pressure switch.

That could be true but around here you never take the condensate from the furnace directly to the outside but to a regular drain line inside to prevent that type thing and if that drain freezes you will know because the entire homes plumbing system will back up. LOL

Some city codes will not let you tie in with sewer lines and remember city code rules.

Do not live in the city if you know what's good for you.

Hi Folks:
Just got back to see all these discusion,Thanks for the help. I will check all these, living our condensate drain in side the basement sump pump well. And sump pump never need to work because remain dry because nothing to pump out.

But I noticed there are some green (like copper sediment) liquid dried out in a drain spout of natural gas line, do you folks know what is it? IF this has anything to do with the Furnace running its own schedule not following thermostat?

We appreciate very much for these helpful suggestion, and look forward to your valuable suggestions.
Thanks,

Folks, just I want follow through the things I have done since my last post.
1. Take Jump off the R & W and put back the orginila red amnd white wire back in the connection spots.
2. Try clean up although there very little clean.

3. Squeeze the condenstae drain pipe and raise a little, and suddenly gush of water starts draing in the drain pipe going into drain hole. I thing about a gallon of water darined.

4. Close the panels.
5. Turn on the power to the furnace and heat came out and house is in comfortable level now.

5. I think this has fixed the problem. Thanks God.

Thanks so mcuh! Have awonderful weekend.

Clogged drain line. Glad you got it going.

Thank you so much.