My 20-yr old A/C unit was checked out by the HVAC guys in Spring and they said everything was fine, but they said we won't really know its efficiency until it gets hot.

Well, summer's here in DC and I have noticed that the A/C unit has to work a lot harder to cool the house. That is, I actually see the temperature in the house go up 74, 76,. 80 while the set temperature is 73! This has been happening regularly for the last two weeks.

The outside fan does turn on fine and I can feel the cold air coming in through the vents. It's just that the A/C isn't able to hold the temperature at 73.

What do you think is the problem? I want to try something before I call my home warranty guys.

Thanks,
K

Is the coil in the unit outside clean? At 20 years old it could probably use a GOOD cleaning not just running the water hose over it. Once you are sure it is clean then the correct refrigerant charge can be done to see how much improvement there will be.

If the unit cooled the house before it should be able to cool the house again. Also the inside coil could also be dirty. There are many items that can cause your problem but cleaning should be done first to create a level playing field so the service person has known circumstances to work from. You never know they might want to just sell you a new unit since 20 years is a long run time.

Thanks, hvac. Is this deep cleaning something that I can do by myself or do I need to call the HVAC guy once again to look into this. Note that I have no A/C unit tools and I have never fiddled with any HVAC system before.

If I call the HVAC guy, his service charge is $60 plus the cost for the repairs. But I am better off going with my Home Warranty since my deductible is $75.

What do you suggest?

I changed my filter, and it appears the house is cooling. I use Filtrete filters that I change once in three months. Would a dirty filter be the cause for the A/C not cooling the house?

Thanks,
K

A dirty filter can cause cooling problems and if this was the cause of your problem you will find out in the next day or two. It make sno difference who cleans the coil BUT they need to know what they are doing and have the proper tools to do a good job. Some use a chemical that is acid base and it actually will create expanding foam which will force the dirt out. Then it is rinsed with lost of water. It takes some time to clean a coil properly. With the tools that I have it takes me at least one hour or more to do the job correctly. While it is apart you clean the inside of the unit,lube and check the motor etc. You also adjust the refrigerant charge when finished and the coil is dry.

Yup, the happiness was short-lived. A/C is back to giving problems. But here's the trend I noticed...

The A/C will work fine during the day when I set the thermostat at 73 (the ouside temp has been 80+), but when the thermostat program changes to Sleep mode at 9:30pm to lower the temperature from 73 to 66, that's when the A/C just gives up (but still keeps working hard) and the temperature in the house just keeps rising... to as high as 81 in the night (outside temperature being within 65-70 range)!

Any idea what's going on? Please reply ASAP if this is a DIY fix since my plan is to put a call in with my home warranty guys today.

Thanks,
K

My a/c is leaking water and not cooling very good. What could I do to fix this problem?

Just a FYI... problem was fixed by the technician. It was a bad capacitor.

With the problem you described I am surprised it was a capacitor. Usually when they are bad the unit will not start or run period.

With the problem you described I am suprised it was a capacitor. Usually when they are bad the unit will not start or run period.

Interesting! That's the report he said he was going to file with my Home Warranty company. He also said he picked up some freon leak, but it was probably very small since he couldn't identify the source. He said not to worry about it. Anyway, let me relate the episode and you can tell me if something's fishy.

After he did the work and explained that he had replaced the capacitor and there was a possible very minor freon leak, he asked me to sign the work order sheet which said I had paid him the deductible. When I told him that I wanted to see his comments in the "Work Performed" section, he said he leaves that empty because he types it up from the office and then sends it to the Home Warranty company. I said I wasn't comfortable signing an empty form, and then he wrote down about the bad capacitor and the freon leak that he couldn't find. He was not displeased or irked by that request.

Do you have any reason to believe there's more to this? The A/C is working fine now.

Thanks,
K

Hvac, any thoughts on my previous post?

Just a FYI... problem was fixed by the technician. It was a bad capacitor.

My A/C fan has stopped turning again after the capacitor was replaced in June of this year. The only work that I did related to my HVAC system was that I replaced the union with a coupling for the gas furnace as seen in this thread: https://www.askmehelpdesk.com/heating-air-conditioning/does-union-placement-heat-furnace-violate-code-508056.html. I've been using the A/C all this while; not Heat.

It did rain overnight however. The circuit breakers were fine too. Is there anything I did yesterday while putting in the coupling that could have caused the fan to not work today? I stood outside to see if the fan was even trying to start when the A/c kicks in, but after adjusting the thermostat and starting the A/C, the fan did not even try to start plus there was no sound at all from the unit even though air was flowing through the vents.

Thanks.
K