cab blower problems

[sts50straight]

I picked up our 1st motor home,it's a 94 Winnebago Warrior (Chevy).The dash blower motor was not working. I installed a new blower motor and it worked fine in the drive way. During our 1st trip,the dash AC worked great but after 5 min the blower would stop. I turned the fan switch off and 30 seconds later I turned it back on and it would work and blow just fine for about 2-5 mins.
I would repeat this the whole trip.What a PITA.

Any ideas ????

Thanks,John........

[njs42]

A short? It worked standing still in the driveway but not moving------maybe a short or ground.

Or something over heating the motor? Does the motor reset when hot, then cooled?
Good luck.

[sts50straight]

It almost seems like some kind of vacuum problem.

[njs42]

Are you sure the old motor did not work---rather than just not come on when you threw the switch?

Me? After having over complicated many things in my life I have learned to look for the simpilist first. A short could be anywhere, in the switch, a twisted frayed wire, etc----

A loose ground has been the frustration of many.

I would make sure I exhausted that possibility first---vaccumn sounds like upping the ante rather soon and a much more difficult situation to resolve.

Nothing in your description leads me to think it more complicated than that----but I am out of knowledge quickly because I am not a mechanic, or an AC whiz----

Hopefully someone will join in that has more intimate knowledge-------

Just dong my best to make suggestions-----

[sts50straight]

I bench tested the original blower and it grunted a little and nothing. I bench tested the new one and it worked fine. Also getting power to the blower at all times with test light.

[njs42]

Originally Posted by sts50straight

I bench tested the original blower and it grunted a little and nothing. I bench tested the new one and it worked fine. Also getting power to the blower at all times with test light.

When moving as well as standing still? If so then you seemed to have ruled out a short----------

Like i said---over heating would be mynext guess can't imagine why how ever----you need someone with more knowledge than mine for sure---sorry I cannot be more helpful.

[doc]

Some sort of DC circuit breaker that when it cools down resets itself maybe?

[wa8yxm]

I do not believe they put overheat sensors in those blower motors.. I do know GM types have a forced air ventlation tube though, do not forget to install it.

I too am going with a problem up-line. Best guess is the switch but I've seen other issues as well.. The fuse holder, any connection, bad wire.. Seen it all and I only work on my own cars.

[sts50straight]

I have the forced air ventilation tube on the fan motor.
Last night while parked I ran the motor home with the "dash' AC on,turned the fan to high and all was good, After 2-3 mins the fan just quit,I switched the fan to low for 10 seconds,turned the fan to high and it would work for 30-45 seconds then quit again. I repeated this process 7 or 8 more times with the same results.

[bigskymt]

Chevy uses a resistor network in the airbox to determine speed selection and a high blower relay for max. speed. If your fan is the single wire type it's easy to check there for voltage when the system is failing. If your airbox is plastic then there should be a braided ground wire from one of the fan housing mounting bolts to chassis ground. If you have voltage at the fan wire and no movement that only leaves a ground problem.
If you have no voltage at the fan wire then you need to check the plug that carries voltage to the resistor network. No voltage there would indicate a fault in the switching assy.
Based on your symptoms I'm guessing a ground problem.

[sts50straight]

I will go out and run the fan motor with a test light attached to the + connector and see if it looses power. I will report back after.

Thanks for all the advise ........ John

[njs42]

JUst for the heck of it I think I would find the ground and pull it off and clean it well then replace. Then test away.

[sts50straight]

With a 12V test light hooked to the + terminal on the fan and its running,all is well.When the fan stopped running the test light went out also.

It appears to be loosing the power.

[bigskymt]

You didn't say if when it failed with the test light it was on high speed or other. Assuming it was high speed and the other speeds worked OK you can check the high blower relay. It could be mounted anywhere on your P-30 chassis but usually in reasonably close proximity to the airbox. I believe it's a plastic relay, maybe yellow. You may have to try and follow the harness backwards to locate it. I believe your system has a 3 or 4 wire harness running to a plug on the airbox. You should have 12vdc+ at various pins on that plug during fan speed selections....including high speed. If the power to the fan disappears on high speed and the power to the plug also disappears check the relay. try tapping on it or reseating the plug.
If you have no 12vdc to the coil of the High Blower Relay the problem is likely in your heater control assy or the wire running between.
Good Luck

[sts50straight]

Is there any way I could get a wiring diagram ? It has to be the High speed relay.
I'm getting close to solving this problem THANKS TO YOU GUYS HERE !!!


John M

[sts50straight]

I found the wiring diagram at the top of the page . My thought is the resistor. Ill hunt for the today,maybe it will be easy to get to and work on.


John

[sts50straight]

Problem solved....The male connector that plugged into the fuse block had a bad connection,also had some scale build up on the connector. Cut the old one off and soldered on a new connector . Fan works on all speeds as it should.

Thanks for all the advice,and for all your help,thanks for this site.




John

[bob1]

I read you posts and I appreciate your assistance, I do not believe that my problem is the same as yours as my fan runs good and does not shut down.

thanks anyway.

bob b