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Topic: A strange noise (Read 717 times) previous topic - next topic

A strange noise

When I was working on my ac I hear a noise like a wheel turning, when I shut off the 12sale sw. it goes away. Could it be a vacuum pump and how long should it run?
1995 U320 40', 2013 chevy sonic toad, my real love are corvettes have owned 30

Re: A strange noise

Reply #1 –
I have been messing with my dash blower lately and hear a noise when I turn the ignition on as well. I think it is a vacuum pump but I am not sure.

Mark
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Mark and Tanya
Milton , Florida
US Navy Veteran (DV)
1999 U270 Special 40' CAI , 2015 Jeep Wrangler Sahara

Re: A strange noise

Reply #2 –
There is a small vacuum pump in the stairwell.  When u turn the key on it comes on and runs for about 60 seconds.  This pump activates the dash air louvers. I replaced mine once and I remember that's it was a Ford product and the newer ones had a different electric connection. 
Dan & Shirley Stansel
2002 U295 4020 AGDS Build#6054
Towing Buick Enclave & M &  G Braking
Emerald Bay, Lake Palestine, Texas
MC# 16650

Re: A strange noise

Reply #3 –
I believe my dash ac louvers have 12v electric motors. But it still may be some sort of vacuum pump.
1995 U320 40', 2013 chevy sonic toad, my real love are corvettes have owned 30

Re: A strange noise

Reply #4 –
On any GV with the Ford AC/heater control, there may be a fault with the slider causing a vacuum leak. This causes the vacuum pump to run much of the time and will damage it. Run the slider about a half inch to the right from the left hand limit stop. Took me over a hour to figure this one out after we brought the coach home.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: A strange noise

Reply #5 –
Thanks Pierce I'll give it a try
1995 U320 40', 2013 chevy sonic toad, my real love are corvettes have owned 30

Re: A strange noise

Reply #6 –
My '95 didn't use vaccum to work the HVAC dampers, it used electric gear motors. One of them failed to stop at the end of it's travel and ran continuously.
John Duld
1995 U320C SE 40'

Re: A strange noise

Reply #7 –
John I'll check that out. I should be able to just change the select sw.and stop the noise.
1995 U320 40', 2013 chevy sonic toad, my real love are corvettes have owned 30

Re: A strange noise

Reply #8 –
Quote from: Pierce & Gaylie Stewart –
On any GV with the Ford AC/heater control, there may be a fault with the slider causing a vacuum leak. This causes the vacuum pump to run much of the time and will damage it. Run the slider about a half inch to the right from the left hand limit stop. Took me over a hour to figure this one out after we brought the coach home.

Pierce

Pierce,

I have the same situation with heat/a/c/recirculate slider on the control head for my HVAC system. 

I worked on my HVAC some today and was able to get the stuck fresh air/recirculate door working again.  Somebody (maybe Foretravel) had put a couple of Sheet metal screws on that door keeping it shut all the time instead of fixing or replacing the  broken cover that holds the vacuum motor on place.  I was told on these older systems the fresh air door is normally open unless you move the slider on the control head all the way over to the left to recirculate which activates the vacuum motor at the bottom of the frigi-cool cover and closes the fresh air door. It probably gives better heat and cooling with that door closed anyway, but I like to have that option!  My '95 Suzuki HVAC works better on recirculate.  I also found a leak in the white colored vacuum line that goes from the firewall to the vacuum motor for the fresh air door.  I cut that bad section off, reattached it to the motor and now it works just fine on recirculate, but the pump won't shut off until you move the slider back because of another leak in the line or in the head.  I haven't been able to trace the rest of that line going in to the firewall back to the head for leaks.  Perhaps it was designed to run the pump continuously (design flaw?) when on recirculate. 

I'll have to fabricate some kind of metal bracket to hold the motor in place that operates the door or buy another plastic cover for about $200 from Acmeairparts  Motorhome Dash AC and Heat systems or Johnny's Radiator & More http://www.johnnysradiatorshop.com/  There is also the junkyard option.  Foretravel has no parts for these frigi-cool systems. 

Jerry
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Jerry and Cindy Maddux
1993 U300/36WTBI DD6v92TA
build 4271  "Miss Lou"
1995 suzuki sidekick 4x4 toad
Gulfport, Ms

"Pride of Ownership"