I have recently acquired a 91' 240 Wagon as a project car. The fan motor blower does not work. No noise is made at all and the fuse does not blow. Is there anyway I can test the motor to make sure this is not some other electrical gremlin before I attempt the dreaded fan motor blower replacement?

Thanks

I'm looking at wiring diagrams for an '81 but this circuit may not have changed. The blower motor is powered from fuse #3 and is the only load. Buy removing the fuse you can test at the fuse for open circuit, short circuit, and resistance of the motor winding. The blower switch should be set to max. You also should see progressively increasing resistance as the switch is turned to lower speeds and an open circuit in the off position.

Hi,

You are absolutely correct in your thinking to come up with procedures to trace the problem out.

I would suggest going over to the fan switch wiring and trace the things out from there.
The test can performed from two directions.
The complete fused circuit has to go to the fan switch first. This will eliminate issues from that direction.
There should be one hot lead the fan switch all the time when the key is on. That confirms the fuse and the ignition switch is connecting.

Having access to the switch will give the console pulled back so a person can hear if the motor hums or not. Using other tactile senses works too!
In most cases, the motor has locked up from dry bearings and it does not rotate any longer.
Unfortunately you cannot just stick a finger somewhere and spin the impellers.

I’m sure it made noises for a long time before that happened. Unfortunately the new owner didn’t get the chance to hear any of it to help diagnose how slowly it died or not.

Showing a resistance is more passive way of testing to showing whether one has an open circuit or not.
There is a resistor in there with several tap out points.
So looking for the LOWEST resistance or Basically some continuity, on all the fan circuits to the motor, but wanting the main one for the HIGHEST speed, to roll the speed up “quickly” on a sticky motor.
That right there, can be tricky for some folks, if they do not understand dancing numbers.
The switch selects which part of the resistors resistance is in between power and the motor.
A resistor can become defective too!
I don’t know how rare that is, but probably is in some cases.

Switch, resistor, motor and any GROUND wire left off from prior work are still possibilities.

The fan switching legs, inside the fan switch, may have gone defective.
That would be a really nice find!

If one wants to get a touchy feel-ee finger to the inside of and onto those impellers, checking for stiffness, involves pulling one of the impeller cover panels is required.

This is the first step into finding out, BOY, this is a ”BIG TEAR DOWN JOB!”

Phil

As machine man mentioned- " GROUND wire left off from prior work are still possibilities." The motor itself has only 2 wires. Power wire goes to the switch and the ground (black) wire has a "loop" end which gets attached to one of the center console posts where other grounds attach as well.-- Dave

On a 91 the original ground wire is not so easy to reach as the center console posts.


--
Art Benstein near Baltimore

“Never underestimate the difficulty of changing false beliefs by facts.” --- Henry Rosovsky

Check your can speed.control switch and the multi resistor for operation before digging out you fan. I've gotten 240 Volvo fans going again by drill a 1/4 inch hole on center of each side of the blower motor shaft can housing and tapped the center shaft a few time each direction. Loosens the down time the car.might have been sitting.

for 99.999% of all electrical automotive things I use my power probe:
https://www.amazon.com/Power-Probe-III-Clamshell-Automotive/dp/B00G4YUWMC/ref=sr_1_6?crid=CTPWAV8LU337&keywords=power+probe+3&qid=1580600244&sprefix=power+pro%2Caps%2C206&sr=8-6
Then you can apply power and ground to what ever I am testing to ensure diagnosis.

The cheaper way is just running a hot jumper wire. But the power probe is so useful!

Hope that helps!

Andrew