We recently had a customer called the tech support line who had installed a Model 7000. The back up heat was coming on with a heat OR cool call and the HP wasn’t running.
Some Heat Pumps have a floating voltage on the defrost pin, usually between 10-12V, that can be enough for our heat pump module to backfeed the defrost signal to the indoor unit module, thus turning on the back up heat and making the system think it’s defrosting.
First, we remove the white wire from the heat pump module. Then, we try to run the system in heat and cool again. If it works with the white wire removed from the defrost pin, we know that the defrost on the heat pump will need to be isolated. With the defrost isolated, the Model 7000 will only back feed the defrost signal to the indoor unit module when the heat pump is actually going into defrost.
