New air handler install; compressor stops running

[mike2007]

I had a new Trane air handler installed last week and the unit has been working very well. But, for some reason the compressor in my heat pump stops running for a certain time period multiple times a day. When the compressor stops, I notice:

1. Thermostat is set and active in "cool" mode
2. Air handler fan speed is high
3. Warm air coming out of vents
4. Condenser(?) fan is still running in heat pump

Is this normal? The heat pump I have is 2.5 tons.

Thanks in advance for any help.

Mike

[jrbenny]

What's the model number of the heat pump? How old is it?

I suspect a recip compressor and no hard start kit added. Just an internet guess.

[mike2007]

Heat pump brand is a Unitary Product Group (york?), model BRHS0301BD. Heat pump is ~ 5 years old and is a 10 seer according to the book.

Why would I need a hard start kit? I never had a problem before the new air handler was installed.

[jrbenny]

Yep. Recip compressor. The Trane air handler has a non-bleed thermal expansion valve. Compressor isn't starting every time due to non-equalized pressures.

Contractor needs to add a hard start kit.

[Airmechanical]

Why would I need a hard start kit? I never had a problem before the new air handler was installed.

EXACTLY!

ya probably have a txv on the new a/h

whats the model # on the new a/h



.

[mike2007]

Model of the air handler is 2TEE3F31A1000AA. Not sure what a thermal expansion valve is, but appreciate the insight. I'll see what the contractor says.

The previous air handler was a comfortmaker (~ 23 years old). How is the new setup different where I need a hard start kit? I have a curious mind, so if you wouldn't mind explaining I'd appreciate it!

Thanks.

[Kevin O'Neill]

Is the outdoor unit going off for about 10 minutes each time? If so, the outdoor unit may be going into defrost. Defrost timers normally start defrost every 30, 60, or 90 minutes. Sounds like a shorted defrost thermostat.

Note also your outdoor unit should match the indoor unit & visa versa. You should change the outdoor unit to match the new indoor unit for best results.

[jrbenny]

Your old air handler had a piston for metering refrigerant. Pressures could rapidly equalize on shutdown. The new air handler has a hard shut off TEV. Pressures take a very long time to equalize.

Good discussion on why you need a hard start kit:

http://hvac-talk.com/vbb/showthread.php?p=1459833

[jrbenny]

Is the outdoor unit going off for about 10 minutes each time? If so, the outdoor unit may be going into defrost. Defrost timers normally start defrost every 30, 60, or 90 minutes. Sounds like a shorted defrost thermostat.

Note also your outdoor unit should match the indoor unit & visa versa. You should change the outdoor unit to match the new indoor unit for best results.

I thought about that, but he stated the ODF is running.

[mike2007]

Is the outdoor unit going off for about 10 minutes each time? If so, the outdoor unit may be going into defrost. Defrost timers normally start defrost every 30, 60, or 90 minutes. Sounds like a shorted defrost thermostat.

Note also your outdoor unit should match the indoor unit & visa versa. You should change the outdoor unit to match the new indoor unit for best results.

I didn't actually time it, but after a little while the compressor does go back on. I immediately thought to myself "why is this in defrost mode?" when I first noticed because it's doing exactly what it would do in the winter. Also, I noticed the liquid line (smaller) was colder than the vapor (larger) line, if that means anything...

The indoor unit is a 13 seer while the outside is a 10 seer. I know this isn't the most efficient, but this also probably means the outside unit will cycle more?

[Kevin O'Neill]

Sounds like a bad defrost thermostat.

Why did you change the unit?

[jrbenny]

Does the outdoor fan continue to run during this evolution as you stated in the original post? If so, it's not a defrost issue.

[mike2007]

Sounds like a bad defrost thermostat.

Why did you change the unit?

Could the contractor have shorted the thermostat? He did change wiring outside also.

The old unit was replaced because it would constantly get "stuck on" and the indoor coils would ice up and the heat pump would run continuously. Also, the fan stopped starting on it's own (motor was shot) and before we bought the house the coils were packed with dirt. Cleaned them out several times, but the air flow just wasn't good like it is now.

[mike2007]

Does the outdoor fan continue to run during this evolution as you stated in the original post? If so, it's not a defrost issue.

Yes, outdoor fan continues to run. At the same time, the air handler fan is running.

I did read the post that explains txv's and a poster was talking about "time-off delays". The air handler that was installed is variable speed and there's mention in the book for a "cooling off delay" where the compressor would shut-off and the fan would continue running, but does that only apply to the inside fan?

[jrbenny]

Yes, indoor fan only.

Call your contractor. Regardless of our guesses, you have system issues.

[t527ed]

Yep. Recip compressor. The Trane air handler has a non-bleed thermal expansion valve. Compressor isn't starting every time due to non-equalized pressures.

Contractor needs to add a hard start kit.

\



agree 100%....

call contractor back before compressor is damaged.