Trane Outdoor Fan Keeps Running


Old 01-13-14, 03:36 PM
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Trane Outdoor Fan Keeps Running

Hello, I have an old Trane that has been perfect up until now and I just want to confirm some diagnostics before I call a tech. The unit is from 1986, TWX742A100A0 is the model for the outdoor unit. The fan outside continues to run no matter what the inside air handler is doing or if the blower is on or not. When the fan is running it is running at full speed and blowing cold air out the vents. I looked at the contactors and didn't notice any melting or pitting but I didnt' look at them with the power on. The unit is heating the house but the aux heat comes on after it operates for a while with the condensor fan running.

I understand I should disconnect the G wire in the thermostat to see if that turns the fan off and if so then the thermostat is the problem. What else should I check? And how much damage can I do if I run the unit with the condensor fan on all the time?

Thanks so much.
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Old 01-13-14, 10:20 PM
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Welcome to the forums.

You need to confirm that the compressor is also running when the outside condensor fan is running.f you can't tell if the compressor is running.....feel the copper lines. One should be fairly warm if the compressor is running.

If just the fan is running then you may have a defective fan motor.... possible shorted winding.

The G wire only controls the inside blower. The Y wire controls the compressor. You can try disconnecting the Y wire to the compressor.
Old 01-14-14, 07:42 AM
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Confirmed that the compressor is definately running as the copper tubing is warm/hot. When I disconnected the G wire at the Thermostat, the outside fan did not run but neither did anything else. Once the G wire was reconnected, everything operated as normal but when the blower stopped, the outside fan just kept on going all night long. Not sure if the blower ever came back on during the night.

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