help with heat pump and reversing valve

last year

so, we bought a house with a basement and 3 heat pumps in may 2021. immediately changed all 3 t-stats to my old nest t-stats. basement ac worked fine summer 21, didn't use heat. ac-summer 22 worked, didn't use the heat. then summer of 23, MIL moved in to the basement and the ac worked. then used the heat in the winter. next, summer of 24 when trying to use the ac, it blew out hot air. tried everything even referencing pics I took when originally switching t-stats. the only thing that got the ac working was reinstalling the original t-stat. then winter 24 she used the heat again and now in summer 25, no ac again. I still have 2 other original t-stats. to try but im wondering if there's something that could cause the RV to be sticking like this after using the heat. any suggestions (besides hire a pro) would be greatly appreciated.

Featured Answer

dovetonsils

last year

last modified: last year

The heat pump may have an issue like low refrigerant. The heat that you got in the winter could be from the backup heat strips. Also note that if the heat pump was working properly in the winter, it often uses the reversing valve in heat mode occasionally also for defrost.

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Comments (6)

PRO
Austin Air Companie
last year
I still have 2 other original t-stats. to try but im wondering if there's something that could cause the RV to be sticking like this after using the heat. any suggestions

You don't really explain AC working. I don't think you realize that working in DIY land typically only means -- the unit is running. In some cases maybe you get lucky, but as time runs on as you've shown your luck runs lean and mean.

The AC working in Pro land typically means a myriad number of checks all check out and everything is in spec. including refrigerant and operational checks.

Many things we don't know here so we're supposed to guess. Could the RV be sticking? Sure just as much the RV may have failed. How would you find that out? Just as much as it could be low on refrigerant issue as already mentioned.

You don't say what is broken because you don't know, maybe you have a bad compressor? bad fan motor? Maybe.

If you had 25 things to guess from, which one would you choose first? The first thing I would have avoided would have been putting older nests on working units. I can't tell you how many times I've found nests as the problem, but as systems age things break. My guessing record as to what it is? I prefer not to guess.

Don't worry we'll fix it remotely? I doubt it.
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Elmer J Fudd
last year
Call a pro.
dadoes
last year
The RV is energized for cool, not energized for heat ... or vice versa ... depending on how a given system is designed. Research that detail on your system(s) and also check how how the original thermostats are configured on that point vs. the Nests.
mike_home
last year
How old is the heat pump?
sktn77a
last year
"The RV is energized for cool, not energized for heat ... or vice versa ... depending on how a given system is designed."

What brand system (condenser) do you have? Most everything except Rheem and Ruud, the reversing valve is energized in cooling mode (non-energized is heating mode).

Doesn't sound like a thermostat issue.