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 Repairing and Servicing Lennox Products
 Repairing / Servicing Lennox Air Conditioning
 Problem on Lennox 80UHG4/5-120A
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dss171

5 Posts

Posted - 07/29/2008 :  09:15:49 AM  Show Profile  Reply with Quote
Help! I have a Lennox 80UHG4/5-120A-2 furance. All the sudden, nothing comes on. I replaced the 3Amp fuse on the Surelight Control Board. The A/C outside unit works fine but the blower does not come on. When I set the stat to A/C, I see both LEDs - slow flash. I measured Y-C, G-C and R-C. They all read 26.2V. But, I got 0V on COOL-H. Is it suppose to read 120V? When I changed the stat to HEAT, I see both LEDs - Alternating Slow Flash. I need help to determine is it the board or the motor fails. BTW, can I connect the COOL-H to LINE-H to test the motor?

Cozy.Support

5851 Posts

Posted - 07/29/2008 :  10:27:42 AM  Show Profile  Reply with Quote
Check the voltage going to the fan motor from the circuit board. With the low voltage inputs you are getting from the thermostat, you should have 120 VAC between ACB Cool and Neutral (RTN) when you have a call for cooling. This is the voltage from the circuit board to the fan motor. This will help you isolate the issue to the circuit board or the motor.



Cozy.Support does not provide a diagnosis for users of this forum. We do, however, try to provide information that will help servicers arrive at their own diagnosis.

Once you know what part you need, you can contact the Cozy parts department by using the link below
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dss171

5 Posts

Posted - 07/29/2008 :  10:33:43 AM  Show Profile  Reply with Quote
Cozy.Support
I measured COOL-H (Perhaps is ACB Cool) and Neutral. I got 0V reading. can I connect the COOL-H to LINE-H to test the motor? Please advise. Thanks.
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Cozy.Support

5851 Posts

Posted - 07/29/2008 :  10:40:05 AM  Show Profile  Reply with Quote
The schematic we have to look at shows the connection as ACB Cool, so we are not sure what the terminals go to on your model. You can connect the motor to line terminals to test, as long as you are sure which wires you are connecting.

One other note. You can leave the wires connected to the line terminals for a few days while you wait for repair parts (if the problem is the circuit board). The motor will run all of the time, and the outdoor unit will cycle with the thermostat. This will keep you air conditioner working until you get repair parts. Be sure to unhook the non-cooling speed taps from the circuit board to make sure you do not damage the motor by accidentally energizing two speeds at the same time.



Cozy.Support does not provide a diagnosis for users of this forum. We do, however, try to provide information that will help servicers arrive at their own diagnosis.

Once you know what part you need, you can contact the Cozy parts department by using the link below
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Cozy.Support

5851 Posts

Posted - 07/29/2008 :  10:42:01 AM  Show Profile  Reply with Quote
We found another schematic. You are correct. "Cool-H" is the cooling speed motor tap. Neutral is marked "Line N".



Cozy.Support does not provide a diagnosis for users of this forum. We do, however, try to provide information that will help servicers arrive at their own diagnosis.

Once you know what part you need, you can contact the Cozy parts department by using the link below
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dss171

5 Posts

Posted - 07/29/2008 :  12:37:13 PM  Show Profile  Reply with Quote
Cozy.Support,
The motor has four wire connected to the control board. Blue and Red go to PARK, White goes to CIR-N and Black goes to COOL-H. I will disconnect the Black wire from COOL-H and connect it to LINE-H tonite. Will keep you in posted. Thanks.
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dss171

5 Posts

Posted - 07/29/2008 :  12:43:23 PM  Show Profile  Reply with Quote
Be sure to unhook the non-cooling speed taps from the circuit board to make sure you do not damage the motor by accidentally energizing two speeds at the same time.

I don't see any labelled as non-cooling speed taps on the Control Board.
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Cozy.Support

5851 Posts

Posted - 07/29/2008 :  1:19:35 PM  Show Profile  Reply with Quote
Heat-H is the heat speed terminal.



Cozy.Support does not provide a diagnosis for users of this forum. We do, however, try to provide information that will help servicers arrive at their own diagnosis.

Once you know what part you need, you can contact the Cozy parts department by using the link below
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dss171

5 Posts

Posted - 07/29/2008 :  5:56:54 PM  Show Profile  Reply with Quote
Cozy.Support
It works. Now, I need to look for the control board replacement. I have a Surelight Integrated control board. Please e-mail me the part #. Thanks for the support.
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Cozy.Support

5851 Posts

Posted - 07/29/2008 :  8:20:56 PM  Show Profile  Reply with Quote
You can use the link in my signature line to contact the parts department and they will let you know which part you need.



Cozy.Support does not provide a diagnosis for users of this forum. We do, however, try to provide information that will help servicers arrive at their own diagnosis.

Once you know what part you need, you can contact the Cozy parts department by using the link below
http://www.cozyparts.com/Lennox-Parts/locator_form.aspx

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