Condensor fan runs but no indoor fan coming on

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Old 05-21-14, 06:22 PM
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Condensor fan runs but no indoor fan coming on

Went out and the fan is running but the refrig line is icing. No inside fan coming on-- what to check? Stat is powered on and seems to be working ok.
 
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Old 05-21-14, 07:15 PM
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Do you have 24 volts to the G terminal or wire ? (to prove if it is a stat problem, stat wire, or furnace problem)

Do you have power going to the motor cooling terminal? (to prove a board or motor issue)

Is the motor hot ?(temperature) This usually indicates that the motor is getting power.

Does the squirrel cage spin freely with power removed? (It may only be the capacitor if this a PSC motor)

Do you have a multimeter?
 
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Old 05-22-14, 03:30 PM
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Yes I have a meter. Can I check 24v at the stat? I have 2 Honeywell 8580's and can pull stat directly off to get to wiring. Stat has power and functions ok.
I'll check power to unit in attic when I can--todays our 10 yr anniversary and about to go out.
Thanks for help.
 
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Old 05-22-14, 06:27 PM
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Ok, there are 2 green lights on the Surelight Lennox board that are simultaneous flashing at 1 sec. intervals. Put meter on G wire and common and no voltage when I hold panel switch in--just lights flashing. Squirrel cage spun freely.
 
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Old 05-22-14, 06:56 PM
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Did you put the fan in FAN ON mode or turn set the thermostat to a call for A/C ?

At the furnace/air handler ....... take a short piece of wire and temporarily jumper the G terminal to the R terminal. Makes sure you hold the door switch in. Tell us what happens.
 
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Old 05-22-14, 07:36 PM
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Turned on fan only and it was only making a humming noise--I jumpered g and r contacts and bottom light stayed green and top light flashed.
Nothing else happened.
 
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Old 05-23-14, 11:06 AM
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I'm going to try hooking the fan up to the safety switch power to see if the fan runs--basically bypassing the board. I'll do that tomorrow (Sat.) morning when it's cool. That should tell me if it's the fan or the board that's bad. Any other suggestions? Thanks for the input.
 
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Old 05-23-14, 12:13 PM
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Is this a PSC fan motor or an ECM fan motor?
Posting the model number might allow us to see the wiring diagram.
 
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Old 05-23-14, 03:07 PM
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Its a Lennox G40UH(X) series furnace. I have the identical stat running downstairs unit, so popping it off and putting it on upstairs would rule out stat being bad.
I put the door switch power directly to motor and fan hummed and I had to spin it by hand to get it moving. My meter wont test capacitors I dont think-- no mfd setting.
 
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Old 05-23-14, 03:42 PM
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If you could spin the motor and start it by hand then it needs a new capacitor.
 

Last edited by PJmax; 05-23-14 at 05:43 PM.
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Old 05-23-14, 05:32 PM
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