This resistor comes into play when the a/c is on and running. The pressure switch on the drier energizes the k9 (I think, or k10) relay, which routes 12 volts thru this resistor to step down the voltage and run the fan on low speed/reduced voltage. You would not necessarily know if it were working or not unless you check the fan operation when the ac has been running for a while, and the pressure demand on the receiver/drier is met. You can check it by unplugging the wires going to the switch on the receiver/drier and shorting them together... the fan should run. If not, the resistor, fuse, or other problem exists. The likelyhood of overheating because of the aux fan not running would likely be limited to idling in traffic for extended periods with the air conditioning turned on.

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RM Smith
1988 560SL

"Where is it again that we are going, and why are we in this handbasket"?