Heat not working but AC does

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Old 10-26-14, 04:08 PM
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Heat not working but AC does

Carrier heat pump. Outside unit does not come on with heat but AC works just fine. Having to use E-heat. Since the outside unit is working fine I'm thinking thermostat. Is there anything else that would keep it from working on heat?
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Old 10-26-14, 04:17 PM
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What are the model numbers?
 
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Old 10-26-14, 04:48 PM
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Heat pump model 38YXA036330
T-stat model TSTATCCPRH01-B
 
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Old 10-26-14, 04:52 PM
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Here is a link to the service manual for your unit:

http://dms.hvacpartners.com/docs/100.../38yxa-4si.pdf

I suggest you shut off power to air handler. Remove wires from R, G and Y terminals on thermostat. Twist these together (I like to use a small wire nut). Restore power to air handler and see if heat pump condenser comes on. If so, it points to a bad thermostat.
 
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Old 10-26-14, 05:31 PM
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Tried it and got nothing. I guess it's not the t-stat. Other suggestions?
 
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Old 10-26-14, 05:38 PM
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Did the system work in heat before? Two possibilities are the reversing valve is stuck and is not switching over from a/c to heat mode or the reversing valve coil is bad.
 
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Old 10-26-14, 05:56 PM
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Yes, the heat had been working fine. Would the reversing valve keep the unit from coming on at all in heat mode or just keep it from producing heat?
 
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Old 10-26-14, 06:24 PM
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The reversing valve is what switches from a/c to heat and vice versa. In a/c mode the outside unit is the condenser coil and the air handler is the evaporator coil. In heat mode the outside coil is the evaporator coil and the inside is the condenser coil. For this to happen there is a valve at the outside unit that has a slide mechanism in it activated by a solenoid. On your unit, the reversing valve is activated in cool mode. I have freed up a reversing valve on a couple of occasions by gently tapping the reversing valve with a rubber mallet. The voltage at the reversing valve can be tested with a voltmeter and the reversing valve can be ohmed. Some hvac techs use a strong magnet to see if the slider moves inside the body of the valve.
 
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Old 10-26-14, 07:23 PM
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Here's a pic of the valve firedawg is talking about.
 
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