Dash A/C fan motor

[Joel Weiss]

I have a dash A/C fan that quits when it is run on high speed.  The consensus is that it is most likely an overheating motor.  We're planning on having it replaced this spring while the coach is having some other work done.  Is there some way to find out what motor was installed in the SMC chassis so a replacement could be ordered before the old one is removed?  

[Phil N Barb Rodriguez]

Joel,

Mine started sqeeking and sticking its tongue out at me a few years ago. I had it changed in Bend at the Beaver Service Center. Maybe a call to them would make it available before you head North.

After watching them do the R&R it's not too difficult. The center wooden console has to come out. The secret to removing it is to find the two screws in the back corners. Once that's done, it appeared to be a piece of cake.

[Karl Welhart]

I think the A/C motor for your coach was supplied by Acme Radiator and Air Conditioning in KC, KS.  Their number is (913) 371-5373.  Do not have a part number, but they may know which one is for your application.  You may also, consider just rebuilding the old one.  I had one done a couple of years ago for $50.00,  The hard part is removing and reinstalling.

[Dennis Mecklenburg]

I also had a dash A/c fan motor that rattled and would not run on High speed. Decided to replace the fan motor, and found the fan cage spindle nut in the bottom of the housing and the cage sliding back and forth on the motor shaft, thus the rattling noise. Installed the new motor, and after further tracing found a poor crimp on a wire splice coupler for the wire for the high speed of the motor. The wire splice coupler was down within the harness, so when I uncovered the wire harness under the dash the motor went on high and stopped intermittently, found the bad coupler, replaced it and the fan runs on high as it should. Good luck with yours !!!
DM

[Joel Ashley]

Had a similar problem and resolution to Dennis' on our old coach - bad wire connections causing intermittent or non-existent high speed fan operation.  So you might check that first if you can access everything.

Have to agree with Karl, too.  I've had local Delco/AC shops rebuild or repair 12v motors of various kinds in the past, and done a couple of them myself.  It may not be as fast, but depending on what's wrong, it can be cheaper than a new motor.

Joel

[Gerald Farris]

 Joel,
Before you replace the fan motor for stopping on high speed you should be sure that the motor still has 12V when it stops. High speed uses a different circuit than the other speeds. The curent for high speed operation runs through a relay to prevent switch damage from the high amperage draw. So normally a blower that fails on high speed only has a wiring problem instead of a bad motor and the problem is normally a defective relay.

Gerald

[Joel Weiss]

Joel,
Before you replace the fan motor for stopping on high speed you should be sure that the motor still has 12V when it stops. High speed uses a different circuit than the other speeds. The curent for high speed operation runs through a relay to prevent switch damage from the high amperage draw. So normally a blower that fails on high speed only has a wiring problem instead of a bad motor and the problem is normally a defective relay.

Gerald

When our fan fails it stops entirely for some period of time; in other words it won't work on any speed.  It's acting as if something has heated up and has to cool for a while.  If the relay is only in the circuit during high speed operation, then the behavior I observe would be more consistent with a motor issue, would it not?

Joel

[Gerald Farris]

Joel,
You may have a bad blower motor, but it is rare for a blower motor to give you the symptoms that you described because the blower motor does not have overload/overheat protection built into it. If it develops an open circuit, it will just quit and rarely restart, or if it develops a short it will blow the fuse.

If the motor quits on all speeds, it is not related to the high blower relay, however it could be one of several switches, relays, or connectors that power the blower circuit. Before I replaced the blower motor, I would be certain that it still had 12V to the motor after it quit to be sure that the motor is the problem.

Gerald  

[Joel Ashley]

And related to that, make sure the motor is well grounded.

Joel A.

[Joel Weiss]

Thanks for the advice; I may run it to force a failure rather than running it on lower speeds to avoid it.  It's a lot easier to diagnose a problem when it isn't an intermittent.