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ahenderson 12-18-2010 07:28 AM

Carrier Hi 90 Furnance variable speed motor
OK There are 100s of posts about Carrier, Ttrane and others with motor problem that can be fixed with a new thermister. Done that, replaced the themister. Have 2 motors both have the same problem .
Motor GE 5SME39-------The family of motors used on these Hi End furnaces
The problem
I cleared out the old fault codes in the ECM. It had 41 of course (blower outside valid speed range)
Hooked the motor up, Turn on the system and it starts through the runup process with enducer motor kicking on ect.
When it gets to the point where the computer tells it to Run the variable speed motor to test it I get a pulse that jerks the motor but it does not start and run. Then it shows Fault 44 (blower calibration fault).
I dont find this problem anywhere on the net. I dont think it is in the motor or the controller attached too the motor. Have 2 motors Replaced the thermister in one and hotwired around it in the other one.
This furnace had a problem for a while that it would stop working. If you turned the power off and back on a couple of times it would start and work for weeks or months.
This thing has a huge 12ADC Transformer on it, Weighs a couple of pounds. Could it be the transformer? How do you check one of these I get 120 volts to it but no voltage (I checked for 12) out of it. I suspect maybe the transformer only puts out voltage when it is gets loaded by the motor controller.
Guys Can you give me some things to check. Is there another component in the motor Controller that is causing this problem. Point me to another place on the web that might help.

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