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I have a recently installed combination of a Goodman electric package unit, and an ecobee smart thermostat.

This morning with the outdoor temp at 36, I was surprised when I peered out the window and saw that my compressor fan was not running (which told me my house was being heated by the electric heat strips in the unit rather than the compressor).

I was surprised because the thermostat was set up to only run the heat strips if the outdoor temp was below 35, and the stat itself was claiming an outdoor temp of 36.

Now I am wondering if the goodman package unit has a thermostat of it's own that switches over to electric heat strip at a certain temp.

Since mid to upper 30's is such a common overnight temp around here during the winter, this could make a big difference in my power usage. Just a few degrees one way or the other would change the percentage of my heating that was with the heat pump by a large margin.

I did some googling and can't find any detailed technical info about Goodman products on line. Just very basic stuff. They don't provide ANY tech support to customers, only through dealers. argh.

  • It certainly is common for a heat pump to have and outside, mechanical temperature switch. That would be the only way to handle the situation before all these high-tech smart thermostats. – JPhi1618 Nov 16 '15 at 19:34
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Being that you are only talking about 1 degree difference I would think it is possible that the tstat began the heating cycle while the outdoor temp was at 35 and rose to 36 mid cycle. Also, it's been 10+ years since I have been involved with Goodman, but they used to have a timer on the defrost control board so that if the unit ran for 30 ~ 120 minutes it would shutdown the heatpump and bring on the backup heat strip. The timing is set via a small dial on the defrost control board. I believe that the default value is 90. At 36° ambient temp, depending on the outdoor relative humidity, your heatpump certainly could have been running long enough to exceed that time.

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Unless you happened to look at the unit during the defrost cycle (which lasts only a few minutes), your thermostat is probably miswired or configured incorrectly. The heat pump should be running with outdoor at 35F, whether or not the heat strips are on.

There could be an outdoor thermostat tied into the heat strip control, but usually that disables the heat strips when 35F or warmer outside and is not for cutting off the compressor. Even in a unit equipped with a low ambient compressor cut off, the cut off should not engage until below 20F or so. If your winter temperature rarely goes below the 20s at night, it is doubtful the unit is equipped with a low ambient compressor cut off at all.

Post the model number of the Goodman condenser and a photo of wiring to the thermostat if you want more comments.

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On some units the condenser fan can cycle to maintain certain pressures. Not seeing the fan running does not necessarily mean that the compressor is not running.

Or it could be in defrost.

  • No unit that I know of will cycle the condenser fan in heating mode except for defrost. Otherwise fan cycling applies only to head pressure control for cooling mode. – user39367 Nov 17 '15 at 4:04

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