carrier furnace wont come on...please help!


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Old 01-20-12, 10:29 AM
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carrier furnace wont come on...please help!

First time on forum so appreciate your help and patience. We have a carrier furnace in attic model 58rav090-LC. Two mornings ago we woke up to a very cold house with no heater working. I called a company out and tech determined it was either the blower or the circuit panel board. His suggestion without much effort, was to replace entire furnace with new model. Our home was built in 1995.

Can't afford new unit so hoping to fix it myself if possible. Found instruction to bypass blower at circuit panel and was able to get blower fan to run so assumed it is the circuit board. Also was able to run self test and witnessed all functions work to light furnace.

Purchased new circuit board, carrier part ces0110057-02 and installed per instructions. Once complete the small red light on the new circuit board panel flashes non stop (old circuit board didn't have light) and blower motor comes on but nothing else fires. Fan blows for about 1 minute or so and then it shuts off. Instructions that came with circuit board says if the lite flashes non stop it could be a twinning issue or polarity problem. The unit is a single unit system so I assume it is not the twinning issue.I replaced all wires just as on original circuit board panel so at a loss and need help.
 
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Old 01-20-12, 10:56 AM
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Start by using a multimeter to measure the voltage being applied between C and R and C and W when the thermostat calls for heat.

That will check to see if the thermostat is in fact attempting to turn on the thermostat. Report back here with the results of that test.
 
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Old 01-20-12, 11:48 AM
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will need to store to get multimeter first. What should it read?
 
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Old 01-20-12, 01:03 PM
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With the power turned on to the furnace and the fan compart door switch pushed in, you should get about 24 VAC.
 
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Old 01-24-12, 05:33 PM
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You should measure less than 3VAC between 24 volt common and neutral.

I've seen another poster with this polarity problem correct it by moving the neutral wire to a different neutral post (of the 5 available).

 
 

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