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Hey, I'm facing a problem that apparently even has a professional stumped.
We have a seven year old Trane XL1400 roof unit. Model WCY036G100 according to the receipt from '03. Several weeks ago we realized that the blower motor was running constantly. We tested turning the thermostat (Braeburn 5000) to off, removing the thermostat from the wall and wiring, and finally shutting off the breaker. Only shutting off the breaker would stop the blower motor, and it would resume when the power was reapplied, regardless of the thermostat.
The unit was serviced twice by a local shop by different technicians, the same company that installed it. First they replaced the ICM Fan Control, a small PCB located behind the panel that most of the wiring is behind. That worked for about a day, but we noticed it resumed running all of the time the following day. They came back out and replaced the Electronic Motor Control, a large, flat cylindrical housing with a couple of circuit boards and some really large capacitors inside that was bolted to the back end of the blower motor. The problem seemed to go away. Today, about three weeks later, I noticed it running again. I tried switching over to heat from AC (this is Phoenix, we're still on AC) and it continued to run. I turned off the thermostat, unplugged it, and finally turned off the breaker, and the breaker off is the only thing that stops it. Turning the breaker back on turns the unit back on again, same as before.
I kept the ICM Fan Control and Electronic Motor Control modules that they removed from the unit. The ICM unit is PN CNT03600. The Motor Controller has MOT06906 on it, but that seems to be the part number for the motor itself rather than for the controller, and I couldn't find a "MOD" number like I expected to. I saw nothing obvious on the ICM board, but I can't really inspect the Motor Controller because one of the PCBs is immersed in a thick rubber layer that was poured on during manufacture. I might be able to remove the rubber layer, but only with considerable effort.
Any suggestions as to what to try next? I haven't had a chance to get back on the roof again to pull the service paperwork from behind one of the panels, but I can do so this weekend when I have a ladder for awhile.
We have a seven year old Trane XL1400 roof unit. Model WCY036G100 according to the receipt from '03. Several weeks ago we realized that the blower motor was running constantly. We tested turning the thermostat (Braeburn 5000) to off, removing the thermostat from the wall and wiring, and finally shutting off the breaker. Only shutting off the breaker would stop the blower motor, and it would resume when the power was reapplied, regardless of the thermostat.
The unit was serviced twice by a local shop by different technicians, the same company that installed it. First they replaced the ICM Fan Control, a small PCB located behind the panel that most of the wiring is behind. That worked for about a day, but we noticed it resumed running all of the time the following day. They came back out and replaced the Electronic Motor Control, a large, flat cylindrical housing with a couple of circuit boards and some really large capacitors inside that was bolted to the back end of the blower motor. The problem seemed to go away. Today, about three weeks later, I noticed it running again. I tried switching over to heat from AC (this is Phoenix, we're still on AC) and it continued to run. I turned off the thermostat, unplugged it, and finally turned off the breaker, and the breaker off is the only thing that stops it. Turning the breaker back on turns the unit back on again, same as before.
I kept the ICM Fan Control and Electronic Motor Control modules that they removed from the unit. The ICM unit is PN CNT03600. The Motor Controller has MOT06906 on it, but that seems to be the part number for the motor itself rather than for the controller, and I couldn't find a "MOD" number like I expected to. I saw nothing obvious on the ICM board, but I can't really inspect the Motor Controller because one of the PCBs is immersed in a thick rubber layer that was poured on during manufacture. I might be able to remove the rubber layer, but only with considerable effort.
Any suggestions as to what to try next? I haven't had a chance to get back on the roof again to pull the service paperwork from behind one of the panels, but I can do so this weekend when I have a ladder for awhile.
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