A/C woes (residential)

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SVeezy

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Well it was due to happen given the age of my air conditioner, so its now giving me some trouble. The unit is about 15 years old I think, I replaced the thermostat I think 2 years ago now and until recently everything worked fine. I've noticed that over the last couple of months the a/c unit cycles on and off far more often than it should. The first thing I did was pull the furnace filter because I've heard a clogged filter can be the culprit but that didn't help. Any advice from the experts on what to do/check next is greatly appreciated. I'm hoping to avoid buying a new unit as this year has already had several unexpected expenses. Also the air is cold when it runs so I don't think the refrigerant is leaking.

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Get it serviced. They will pressure check it. We had a similar issue with a new machine and it needed extra refrigerant.
 
If you have a humidifier make sure the dampers are set properly. If the dampers are open, the coil could be freezing up.

Does your furnace have error codes (either on a led display or blinking light)?

Has someone left a window open which is increasing the load on the ac?
 
GreyGhost said:
If you have a humidifier make sure the dampers are set properly. If the dampers are open, the coil could be freezing up.

Does your furnace have error codes (either on a led display or blinking light)?

Has someone left a window open which is increasing the load on the ac?
Click to expand...
The windows aren't open and there isn't a humidifier. It's an older furnace and I dont recall seeing any error code lights but will take another look, thanks

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Let me know if you need an hvac guy. I can send you my BIL's #

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When the A/C went on my van it started the fast cycle. They put a chemical in hat rejuvenated the seals and it got me another year. Not a cheap chemical BTW.
 
I'm reasonably well versed with HVAC...but I'm not sure I understand your exact problem. Is it not cooling the house? You seem to suggest it is still accomplishing that? Is there lots of air flow, are the vent temps as low as they should be (or were before?), and is it effectively cooling the house?

Short cycling can be caused by a few things, but if it was low refrigerant causing it (IE, a leak) it's usually accompanied by other symptoms such as the evaporator freezing up....which causes reduced (and eventually, almost no) airflow and then the house heats up...when you turn it off for a while the giant block of ice enveloping the evaporator melts, you turn it back on...and everything seems to work fine for a while again...until it freezes up again and the cycle repeats.

So..you mention you replaced the thermostat a few years ago...with what model? If it's a smart thermostat it's possible that a recent firmware update or something changed some critical settings such as the swingpoints, dead zones, or CPH (cycles per hour) settings and they may just need to be adjusted.

FWIW 15 years old isn't terribly old for HVAC components.. Our system is original to our house from 1988 and it's still working. Not anywhere as efficient as a new furnace/AC, absolutely..but still working.

Lets assume it's something simple before worrying about it being something bigger.
 
Probably low refrigerant issue . But last few days the heat has been great so your AC may work harder .
 
Sorry for disappearing on this all. Everyone in my house has been sick over the last week and otherwise just busy.

PP, the unit was otherwise working well it was just fast cycling ie on and off more frequently than it should. I'm usually pretty handy but don't have a whole lot of experience with hvac. Per other suggestions I hosed down the unit and that didn't help.

The more I thought about it I was convinced that although the thermostat was only 2 years old it had to be the issue as the air was ice cold while it was running.

I decided to order the nest thermostat which is the one my wife wanted 2 years ago but I'm cheap so...

Installed the nest and everything is working properly again. Had a couple small headache with the wiring but got that all figured out.

End result is everything works and I actually really like the nest.

Thanks all for your input on the matter.

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Interesting, not sure if it was mentioned but what thermostat did you have before the Nest (the one you installed 2 years ago)?
 
Full disclosure now that I'm thinking...

I was able to get the a/c working, I was able to get the heat working. I was NOT able to get them working in HEAT - COOL mode which is supposed to automatically switch between the 2. There was an error code but at the time it was late and I was ready for bed so I was happy to have them work independently.

Any expert advice? I will see if I can get the error code again.

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