Figure 1. (Click on the image for an enlarged view.)
In this troubleshooting situation, we have a customer who has called to say that their 12,000 Btu through-the-wall unit is “blowing cool air even though it’s set for heat.”
Here’s the unit’s profile: 1.
It’s a heat pump with a three-speed motor. 2.
It operates on 240 vac. 3.
There is no step-down control voltage system for mode selection or temperature control, only the push-button and thermostat control on the unit itself. 4.
A dual capacitor is employed and both the compressor and fan motor are PSC-operated.
Upon your arrival, you find the following conditions and get the following results with your electrical tests: 1.
The outdoor temperature is 50°F. 2.
The indoor temperature is 65° and the unit is set in the heating mode with the thermostat turned up to a maximum setting. The compressor is running and the blower motor is operating on high speed. 3.
A voltage check at C on the capacitor (see the Figure 1 diagram) and L1 on the switch shows 240 vac. 4.
A voltage check at RV shows 240 vac.
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