Recently a customer called the tech support line for our help. They had installed a Model 7000 and the back up heat was coming on with a heat OR cool call and the heat pump 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.
To solve for this, 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.