Troubleshooting Challenge: A Small Room-Size Heat Pump That's Not Heating
September 6, 2010
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.
Your troubleshooting question: Which component has failed?
Compare your answer with ours by clicking here.
Publication date: 09/06/2010