One day my wife complained about the heater not working, so I suggested she contact a repairman. One showed up and did some rudimentary diagnostics. The quote for repairs was more than $700.
Needless to say, my wife was in shock. I stepped in. The quote called for a new blower motor, a new control board, and other miscellaneous parts. I started sleuthing and found, thanks to my ESR meter, that the starter cap on the blower was bad. The field windings were fine. I ordered a cap, since no one local could cross-reference the part. It came to less than $20.
Now for the bad news. The PCB had a connector that was fried and traces that were gone. The traces had led to two relays. One was for the blower, and the other one was for the five heater coils. I measured the resistance of all five coils, and they were fine. So, what had happened to cause this extensive damage?
The PCB not only had traces handling the high current. It also had some additional jumpers that looked like they had been modified. From what I could tell, the starter cap failure pulled enough current to heat stuff up, and one of these jumpers actually de-soldered itself and shorted to an adjacent trace.
This board was probably adapted to this heater model, since the remaining control relays were located on a separate assembly. The schematic showed a series of models boasting two heater coils up to ours, which had five.
So, I figured the control board was designed for small units and “made” to work for our model. The control board was $210, and I still needed to replace the mating connector that was damaged. So, I decided to remove the connector from the PCB, drill out the holes, and add my own #8 high temperature wire.
I used the wire to replace the burned traces. I cut off the mating connector and procured higher temperature-rated wire nuts. With everything back together and the new cap installed, I cautiously reset the breakers. It worked like a champ, and the total repair cost for me was under $40.
This entry was submitted by Bradley P. Miller and edited by Rob Spiegel.
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