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Topic: Intermittent fan motor function (Read 923 times) previous topic - next topic

Intermittent fan motor function

I have a 2003 U295 that is demonstrating intermittent dashboard fan operation.  The fan operates normally for a period of time, then will stop operating, regardless of setting.  Next startup the fan may, or may not operate normally on all the different settings.  It's difficult to diagnose as it seems to operate normally during those times that I am in a diagnostic mood and not driving.  I would be inclined to think that I am experiencing a "ground fault", however, when I approach the fan switch, I find a 3 wire switch with no discernible power source or ground.  The schematic merely confused me.  Anyone experienced this problem?

Re: Intermittent fan motor function

Reply #1 –
We had that exact problem in the 2003 we owned; initially tried replacing the selector switch (worn contacts being the thought) but that didn't fix it.  One shop looked at it but couldn't resolve it.

I don't know if I still have the records (they aren't on this computer), but when Old Town was open and Issac Anderson worked there, he found the problem and fixed it.  If I can scare it up I'll post.  It involved replacing an electrical component in the dash area, IIRC.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Intermittent fan motor function

Reply #2 –
Thanks Michelle, I got the impression that it may be component related from earlier foretravel tech support, however, was unable to follow up as I was in Alaska.  The recent effort at tech support didn't supply the same results, so I appreciate any help.

Re: Intermittent fan motor function

Reply #3 –
No luck on this end yet.  Maybe they are in the paperwork we gave Dan Weaver when he and Sandy bought our coach.

If that doesn't pan out I can ping Issac and see if he recalls what he had to do.  It's a shame he's no longer in MH repair. 
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Intermittent fan motor function

Reply #4 –
Found the receipt.  Bridge rectifier. 

Now, we did also have a dash a/c not cooling at the same time, which was a bad condenser fan.  Issac replaced the condenser fan, 15 amp breaker, installed a second 15 amp breaker to separate alternator and condenser fan (according to the notes on the receipt).

At the time, the A/C diode was $35.44, the dash condenser fan was $186.49, and the 15 amp auto resetting breakers were $9.99 apiece.  Unfortunately, I don't have part numbers.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Intermittent fan motor function

Reply #5 –
Quote from: Michelle –
Found the receipt.  Bridge rectifier. 

Now, we did also have a dash a/c not cooling at the same time, which was a bad condenser fan.  Issac replaced the condenser fan, 15 amp breaker, installed a second 15 amp breaker to separate alternator and condenser fan (according to the notes on the receipt).

At the time, the A/C diode was $35.44, the dash condenser fan was $186.49, and the 15 amp auto resetting breakers were $9.99 apiece.  Unfortunately, I don't have part numbers.
This is good information for me, as my condenser fan was what was playing havoc on my dash volt meter. After new fan motor voltage stays constant. I might add the second 15 amp breaker to eliminate that happening again.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Intermittent fan motor function

Reply #6 –
My fan speeds were intermittent when I took the coach to FOT last year. They fixed it by replacing a bridge rectifier. Must be a common failure.
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer

Re: Intermittent fan motor function

Reply #7 –
Would a bridge rectifier affect the volt meter?  When dash air is on, my volt meter will run up to 15.5 V and back down to 12 V and then level out at 13.5 V.  It cycles like that about 3 times a minute.  When the voltage ramps up my dash fan ramps up with it.
2000 U295 40'
Build 5635

Re: Intermittent fan motor function

Reply #8 –
Where is this bridge rectifier located?  My fan has been intermittent and now has quit completely.
Keith
2003 U320 38' #6197
 

Re: Intermittent fan motor function

Reply #9 –
My dash AC was doing the same thing.  It wasn't going off, but down to low fan speed, which is so low you can barely tell it's running.

The dash AC in my 2003 U320 was manufactured by a company called SGM Company in Ohio.  I called them and they provided the schematic for the AC, since it was not in my manual (attached).  I spoke with Shawn over there a few times and started tracing out the issue.

As to your question about the switch, here's how that works.  There are 3 posts marked B , L and H.  B is battery.  When the system is on, this should have 12v to it.  There is also a small wire that comes off of this and goes out to the temp selector switch.  When the system is turned on with the mode switch, it defaults to low fan speed...so if this switch isn't working, you should always have low.  There is no low speed output from the fan speed switch, so with no output, the system runs in low.  The "L" output is actually the medium speed selection, which sends 12V down the yellow wire.  The high speed selection sends 12V out the orange wire, directly to the fan connector.

First, I checked for power at the B post and found 4.5 volts.  Shawn and I both had no idea how this was possible.  I later unplugged all the wires from the fan speed switch and found 4.5 volts coming back on the orange wire from the motor...backfeeding through it I suppose.  I was seeing 4.5V at the B post because the switch was in the high setting when I tested it.  With the wires disconnected, the switch tested good and I found no voltage on the red wire.  I traced that wire back to a joint connection coming out of a relay where there was 12V.  I did a continuity test on the wire, and while it had continuity somehow, no voltage was getting from the relay to the switch.

I ended up cutting the wire from the relay and ran a new wire from it to the switch and voila!  It all works perfectly now (in the driveway anyway).  Next trip is in 2 weeks for a formal road test.
Keith
2003 U320 38' #6197