Condenser running with heat... here's a good one.

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  #1  
Old 01-06-19, 09:01 AM
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Condenser running with heat... here's a good one.

The set up: baseboard hw via nat gas, 2 zone - working great for 20 yrs. Central air whole house one zone added 2011, air handler in the attic and compressor/condenser outside at the side of the house - working great from day one. Switch t-stat from cool to heat back in Sept/Oct and everything has been working normal for months. Wake up New Years Day and the outdoor compressor/condenser is on, not the air handler. I check the t-stat to see if my wife switched the t-stat setting and it's on heat as it should be. Completely shut off the t-stat and outdoor unit is still running. Only way to turn off outdoor unit is pull the outdoor shutoff or flip the breaker in my house's panel. Where do I start investigating myself before I call in a pro? Thanks.
 
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Old 01-06-19, 07:41 PM
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What type of thermostat controls the cooling? Try disconnecting the Y wire there to see if it shuts down the compressor.
 
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Old 01-06-19, 08:03 PM
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Two transformers to one thermostat. Possible bad thermostat now.
 
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Old 01-07-19, 03:46 PM
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Vision Pro 8000. I'll swap out t-stat this week and see. Thanks!
 
  #5  
Old 01-07-19, 04:28 PM
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If you have two red wires..... Rh and Rc..... make sure they are kept separate and installed in the right location.
 
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Old 01-11-19, 03:25 PM
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Step 1, installed new stat...changed nothing.
Step 2, pulled Y wire...changed nothing.
What's next?

installer said it sounds like a mouse in the wall chewed something - in all my remodeling I have never seen evidence of any rodent so I'm thinking something outside is causing the trouble. I investigated the attic and everything looks normal, like it has from day 1, now mouse remnants.
 
  #7  
Old 01-11-19, 03:47 PM
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The Y wire from the thermostat and a C from the air handler go to the outside unit.
I would next disconnect the wires at the outside unit to verify that it is a wiring issue. Otherwise possible stuck contactor in outside unit. If not then check the wires at the air handler. Then check wiring inch by inch.
 
  #8  
Old 01-12-19, 12:12 PM
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First off the LED blinker was blinking 8 times, tag says contactor or wiring. Ok here is my next step...with outdoor shutoff key (?) removed i removed 24v wires from contactor, plugged in shut off back in and compressor and fan blades turned on. Pulled shutoff key out. Plugged 24v wires back in. Went to the attic and pulled cover off air handler and everything looked good. Followed wires thru all the insulation and everything is intact, no chewing and no jacket tears.
Not sure this deduces anything but y next step: I put shutoff key back in (compressor turned on) switched stat to cool, set to 63 and air handler came on and compressor shut off. Brought stat up above house temp and after stat 'clicked' air handler ran after the fact like usual and shut off, compressor still off. Does this satisfy that the stat wires are fine and it's a contact problem?
 
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Old 01-15-19, 03:49 AM
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Guess I'll just replace the contactor when the weather warms a bit.
 
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