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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22541
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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our heat pump cycles for cooling inside the unit, but the fan

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our heat pump cycles for cooling inside the unit, but the fan on top of the box does not come on or make any noise at all. I can turn it manually with ease in both directions. Any ideas?

This can be either a bad defrost board or a bad motor. Do you have a volt meter?


Customer: replied 3 years ago.


Customer: replied 3 years ago.

I have a volt meter that is rated to 300 V maximum

Thank you,

follow the black wire from motor to board.

Are you familiar with this circuit board location?

Customer: replied 3 years ago.

I am not.


In the electrical section is where the power enters the unit. There is a defrost circuit board in that area. The black wire for the motor comes from that board.

If you get me a model number of the unit I can send a pic

Customer: replied 3 years ago.

ok Trane XE 1600

Looks like this


We need to see if that terminal from the defrost board is putting power out.

Customer: replied 3 years ago.

Just got to the board. I have a flashing red "status" led on the board. I cant tell which terminal we are trying to figure out if it's putting out power. Picture is small and I can't enlarge on this end

did you follow the black wire from the fan motor?

Customer: replied 3 years ago.

Ok. I located where the black fan wire goes into the board. how do I test for power?

put meter lead on that terminal and then other meter lead on the contactor

but put meter on red wire side.

so one lead on contactor red wire terminal and other lead on black wire terminal on defrost board.

Tell me if 115v or 230v

This must be done while it is running

Customer: replied 3 years ago.

I put the AC on, unit comes on about 10 seconds later. Fan does not come on. Unit runs for two minutes, then shuts down. During this time I put meter on with red to black on terminal and black to red wire on contactor. My meter reads 60 on the DC scale or 2 out of ten on AC scale.

Thank you.

it appears the defrost board is can bypass to test.

Take the black motor wire off the board. Then attach it to the black wire side of the contactor.

So red wire is one side and the black motor wire mounts with the other black wires on other side.

Then turn on....if board is bad the fan will start and run fine for ac. But the board would need to be replaced before heating season.

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Customer: replied 3 years ago.

went with the bypass and the fan makes a bad sound and when manually turned it goes slowly for a bit and then stops. Fan motor seems bad, time to call in a technician

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