Testing AC Cabin Fan

I am fairly sure the fan to my blower motor in my 1993 240 is shot. Is there a way to make sure that it is NOT the switch or the resistor assembly before I replace it without taking everything apart?

fuse

In the high position the voltage to the resistor flows directly to the fan. If it will not run in high with a good fuse there is a very high probability that the motor needs replacement.

It could always be a connection issue but you will not know that until you are half way to replacing the motor.

Do you have an incandescent test light, or a multimeter with a 10amp (or higher) rating? If so, pull fuse 3 (25A fuse for blower fan) and connect the test light or multimeter (on 10amp or higher setting) across where fuse 3 was.

Turn on the ignition and turn the fan on low. If you have a test light, it should light up. Turning the fan up should increase the brightness slightly. Even a good fan probably won't spin due to the added test lamp in the circuit.

If you're using a meter, fan on low should be ~2 amps, then ~3.5 amps and ~5 amps for the next couple switch positions. A good fan should be spinning. If your meter is only good for 10 amps, don't go above 5 amps or else the next switch setting may pop the tiny-little-hard-to-find-a-replacement fuse in your meter.

If you're seeing increasing brightness, or increasing current, then the wiring and resistor are OK but the fan is likely stuck.

In the event the circuit is open, and there is no current flow in any position of the speed selector, the only way I know of to firmly rule out easy-to-fix items like the wiring and connectors, is to peel back the front of the console and sneak a piercing probe to the motor's red wire directly, and verify the voltage being supplied. Do this especially if you think the '93's blower has already had hands-on in its life, or if the blower died suddenly and unexpectedly.