Heat Pump Guys - Need help troubleshooting.

[tlmartin84]

Background:

Went home, house was hot, Thermostat was on cool, Air Handler was blowing warm air. I checked the coolant lines, they weren't cold. Went outside and checked the heat pump, it was dead.

Pulled the cover, the LED monitor referred me to an "open circuit". I checked the capacitor, it appeared slightly bulged and oily. I tested it with my multimeter and it was dead.

I replaced it. Turned the system back on and voila..........cool air.

Now onto the problem:

The units will not shutdown when they have reached the setting on the thermostat. If I bump the temperature up on the thermostat the relay kicks and the system shuts off, if I don't touch it, the whole system just keeps running.

I am guessing that it why the capacitor went bad? I thought it was the thermostat, so I placed it on my other unit, it works fine.

Any ideas on what could be causing it to stay on?

 

[Ohmthis]

Does the temp over shoot, meaning does it get colder than what you've set it for? If not and just runs a long time to reach or not at all, you have some performance issues. It could be dirty filter, dirty coils, dirty blower wheel, low charge, weak motors, weak compressor valves, a slight restriction, and the list goes on and on. A series of checks need to be done.

 

[tlmartin84]

It is overshooting....but not registering on the thermostat.

I set a thermometer beside it. It was three degrees below, I was certain it was the thermostat until I switched it and it worked fine on my other unit....

The system is 5 years old, I have two Identical systems, both 2.5 ton units, one for upstairs, one for down. They are clean, and have always worked well.

 

[Ohmthis]

Did you switch the tstat with the other?

 

[LS6 Tommy]

X2 on the t-stat being OK & the long run time is due to system performance. +/- 3* isn't much of a variance. The stat or the thermometer or both may be inaccurate. That fact that increasing the set point shuts the system off on the "problem system", but operates properly on the other system, tells me it's not the t-stat. Does the room actually get too cold to be comfortable? Is the stat mounted where it may be sensing a higher temp than the space, like on a wall that is allowing warm air to leak through the hole for the wires out through the stat?

Tommy

 

[tlmartin84]

Thanks for the replies, as of now the issue seems to be resolved.

I replaced the thermostat with an identical one. I don't think that was the problem, because the original is still working my other unit just fine.

I did increase the fan speed, I noticed that the working unit was set on medium, and this one was on low. I actually adjusted both of them to high, I have never felt like they pushed enough air, they are slightly more audible now, but they don't bother me.

I guess time will tell..............I may be digging this thread back up in a few months.