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Exterior heatpump unit shuts off randomly

278 Views 11 Replies 2 Participants Last post by  roughneck
I had this issue with my previous old unit and this one that was installed approx 3 years ago.

This is a heatpump system and I have the issue in heat or cool mode and have replaced the thermostat.

Randomly the outside unit will not power on (or shuts off while running, not sure which). I discover the issue because the fan is running without it getting any warmer (in winter) or cooler (in summer). I have 2 double breakers for the system and neither will be tripped. I can turn off the thermostat and both breakers for a couple mins, then turn them both back on and set the thermostat and it works again.

Some research I have done may indicate I need a hard start capacitor. Or, that the the system may be overheating due to not enough airflow due to closed off vents etc.

I do have a couple vents closed off but seem to have a lot of airflow through the many other vents I have. Filter is changed regularly. One other thing of note is that my house is about 40 years old and on a slab. One company that I got a quote for when replacing the unit mentioned that they may need to run new tubing through the attic as the tubing going through the slab is too small for a modern system. The company that ended up replacing it didn't think it was an issue but did have to use a reducer on the lines.

So, I am thinking of replacing the breakers for good measure and then consider a hard start cap (they are cheap enough). Other than that, any suggestions on what the cause is or how to try to track down the cause?

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Do not replace any parts until troubleshooting is done.
It sounds as if the unit is shutting off on a diagnostic code.
Next time it shuts down open the panel and see if there’s a code. Check for an active call with your meter.
What’s the model number of the unit?
Check for an active call to the outdoor unit.
Could be a condensate protection device, a power conservation device or something else.
But still, don’t start replacing random parts. Breakers and compressor starting components can be easily tested with your meter.
No, check the live control voltage with your meter.
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High pressure switch lockout means a problem on the indoor coil in heating mode, the outdoor coil in cooling mode.
Is the indoor coil clean? Blower running properly? Blower wheel clean?
Honestly you may want to get someone out to check operating pressures.
Yes, it’s either an airflow or refrigerant related problem. Lack of heat transfer is the issue.
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