Re: Summer Trip - resistor pack

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Posted by Frankenbiker ( on 19:51:34 07/30/07

In Reply to: Summer Trip - resistor pack posted by kcburb

: I had to replace the resistor pack while I was up there - 2nd one in 2 weeks. I know this is caused by restricted air flow due to frosting. I am not sure what causes the frosting - low or high freon. Can someone let me know?

Usually it's low freon.

: Also, the resistor pack looks fine when I pull it out. What is it that fails on them?? Can they be repaired???

I haven't seen a GM resistor pack, but the ones in my Freightliner have a thermistor(? thermal fuse?) on them that internally opens (permanently) when the resistor pack temperature gets too high. It looks somewhat like a diode. The resistive elements never break, but DO get red-hot if there is no cooling air going across them.

I kept blowing them when there was no other indication present. Turns out that the blower motor starts pulling more current as it ages, until it pulls enough current on lower speeds to overheat (and burn out) the resistor pack, even if there's air going over the thing.

You might check and see if yours is old and pulling too much current by (if there's one present) bypassing the thermistor(?) with a series of small-value fuses (i.e. 5-amp, 10-amp, etc) and seeing if it still blows. If it is, you may be able to buy yourself a little bit of time by using electrical contact cleaner on the commutator of the blower motor (if you can reach it).


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