Goodman CPLE24-1C Heat Pump. Bad defrost circuit board?

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sparker

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Here's my problem:

On cold nights, temps in the 20's here in NC, my heat pump goes into defrost cycle but seems not to come out, blows cold air with no warm air returning. During the day, when the outside temperature increases, the defrost cycle works fine. i.e. goes into cycle for about 3-5 minutes, fan turns off, cold air blows out, but the heat then returns as normal. Does this sound like a bad defrost timer circuit board?

It seems like heat kits are optional in this part of the country. I looked at my air handler and stamped on the placard was "No Heat Kit."

It only does this on cold nights, but otherwise the system seems to work fine. Any input would be greatly appreciated!
 

Jimbo

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Electric heat kits are needed where outside temperatures get too cold for the heat pump to funcion well , or at all. 20º is probably below where that heat pump will work.
 

SHill

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There is not anything wrong with the defrost board. Remember, when a heat pump goes into defrost cycle, it is actually going into the AC mode. When in the ac mode, the liquid line heats up to melt the frost/ice buildup on the liquid line & coil inside the HP. This also pushes cold air thru the ducts.

If you don't have any type of aux heat, like electric backup, then you will only get cold air until the unit goes out of defrost mode. The colder the temp gets outside, the longer the heat pump may stay in defrost mode.

Being low on freon also may cause this. But in your case, I don't that is a problem.
 

BruceNC

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I have nearly identical symptoms, but I will add that this summer, the reversing valve was heating instead of cooling. When jumped the house seem to cool fine. The Tech could not figure out what the issue was. I removed the jump for heating season and the house maintain temp as long as temps are near freezing or above. When temps drop in the lower 20's or colder the 1st floor unit can't maintain temp. The 2nd floor does not have same issue. Also I have noticed much higher electric use the past month with the colder weather. It seems like the unit is no blowing warm air often (confirmed with infrared gun). The delta is often only a few degrees, but will increase briefly to 15+ degrees. Would this seem to indicate defrost board or low refrigerant. It is possible the heat strips are undersized -- it is a new construction house. It is possible the unit goes into defrost too often and/or for too long. The unit on 1st floor is 2 ton and 2nd floor is 2.5 ton. We also have a sun-room with a lot of glass which may contribute to heat pump working harder in winter. Thoughts?

[Edit] I should have added that both my units have heat strips installed. Also the summer issue with the reversing valve might be a different issue and/or unrelated. That said my secondary question what would cause heat pump reversing valve to produce heat instead of AC. it doesn't seem to be thermostat as I swapped with 2nd floor and either thermostat appears to operate on 2nd floor.
 
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WorthFlorida

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With a heat pump you absolutely need auxiliary electric heating elements in the air handler. They are not that expensive to add. A two stage heat and a one or two stage cooling thermostat will be required. A smart thermostat can determine when to kick in the aux heat (Honeywell calls it emergency heat). Most thermostats of any kind can manually switch out the HP and use the electric or auxiliary heat only.

Of the temperature is above 32 a smart thermostat can determine if both are needed if the temperature does not rise after a period of time or if the house temp falls while in HP mode. If the set temperature is two degrees above the room temp the thermostat will turn on the aux heat.

If you read through this users manual you can read between the lines and understand 2 stage heat. Besides it’s one of the best smart thermostats out there. https://yourhome.honeywell.com/en/products/thermostat/wi-fi-smart-thermostat-rth9580
 

WorthFlorida

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I should have added that both my units have heat strips installed. Also the summer issue with the reversing valve might be a different issue and/or unrelated. That said my secondary question what would cause heat pump reversing valve to produce heat instead of AC. it doesn't seem to be thermostat as I swapped with 2nd floor and either thermostat appears to operate on 2nd floor.

FYI
The reversing valve of a heat pump is controlled by the thermostat by the wire on the “O” terminal. Most units 24volts is put on this lead to operate the reversing valve for cooling. Without voltage the valve is not activated and the system is in heat pump mode. This is all controlled by the thermostat. Some AC units, I think Trane, it’s the opposite. No voltage it is in cooling mode. A smart thermostat program has this option for two stage heating.

At the reversing valve check for proper voltage and for good connections. If all is good the solenoid may be bad.
 
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