Heat Pump - AC

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Old 05-05-02, 09:21 AM
Ron_Evans
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Heat Pump - AC

Will not come on. Manual fan switch does not turn on the fan. Air handler has 3 fuses inside and all ck out ok. Has 2 circuit boards but I do not know how to tell which one is not working. Anyone know how to check?
 
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Old 05-05-02, 09:36 AM
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More Detailed Information Requested

Hello Ron_Evans. Welcome to our Heating and Cooling forum and the Do-It-Yourself Web Site.

Kindly provide more detailed information. In depth and detailed information helps to explain the situation a manner that allows the professionals to offer the best possible helpful suggestions and advice.

Also provide the units brand name, year, model, serial numbers, if available. Any and all detailed information would help greatly.

Any and all additional detailed information you can provide may help to expose a clue regarding the units current problem and help to determine the exact repair to the problem.

Your assistance in this matter would be beneficial.

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Retail parts dealers can also help determine what the possible problem may be. Bring the make, model and serial numbers.

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Old 05-05-02, 09:39 AM
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check the

transformer, should be putting out 24 volts. there may also be a small "auto type" spade fuse. if you pull the cover off the tstat and jump r and g, the fan should come on if it does, bad tstat.
 
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Old 05-05-02, 07:45 PM
Ron_Evans
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This is a 7 yr old Lennox model C22-46-FC-TXU-2. I had checked that auto type fuse & it was ok. Connecting R & G does not start the fan. There does not seem to be any low voltage.
 
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Old 05-06-02, 04:20 PM
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go to the

transformer, see if 120 volts is going in, and 24 coming out.....sounds like bad transformer
 
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Old 05-09-02, 09:03 AM
Ron_Evans
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Angry

I swapped the transformer with the identical transformer on one of the other working units. and it did not have power. The faulty units transformer works in the good unit. The printed circuit board it connects to does have power (high voltage at the glass fuse & fuse is good. Is it the board? I presume the limit switch is ok since the transformer board has power.
 
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Old 05-12-02, 07:16 PM
ahasbeen
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If you've determined your xformer has 24 volts output and you can't run the fan by jumpering R & G at the stat, then you've got an "open" low voltage wire someplace, the OD unit is out of gas (off on low pressure switch), or the circuit board itself is bad. You ought to jump R&G, go to the fan relay to see if the coil is energized by checking for 24 volts across the coil. Its possible the relay contacts are kaput, not allowing high voltage to go to the fan motor.. You also can eliminate the xformer by calling for cooling at the stat. Don't know what kind of backup heat you have but if there is a limit control for the fan, it could be the culprit
 
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Old 05-13-02, 04:56 PM
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just in case

it is the wire itself, disconnect t stat wires from board, be sure 24 volts is entering board, have it b/w r and c, then jump r and g if no fan but 24 at r and c , bad fan relay, most likely on the board, ie bad board....does heat work? low refrigerant tripping low pressure switch will prevent o/d unit from coming on, will not affect fan. check if the red wire to the tstat runs through a condensate pump or float switch
 
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