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small motor sound under dash

Yahoo Message Number: 84510
After living in this coach fulltime for 14 years, I finally got curious enough to investigate. When I turn the key to the ON position, there is a small motor running sound from under the dash. The sound will last for 5 to 10 seconds. Had read that some coaches had 2 hot water , so just assumed. Was looking at the manuel, and saw it has just 1, back in the engine compartment. Now wondering what the sound is. Back in the day, the A/C heater control gates were operated by vacuum from the engine in a car. Best I can recall, our engines do not. So is there a vacuum pump making this noise?

Bill Dane 99 Allure 30326

Re: small motor sound under dash

Reply #1 –
Yahoo Message Number: 84511
My rig had two of those school bus pumps. One forward of the engine and one behind the front curb side bumper. I removed the one at the rear after several failures. The front one still works.

Dean

95 Magna 5280

Re: small motor sound under dash

Reply #2 –
Yahoo Message Number: 84512
Just a shot in the dark, but could it be the GPS starting up? We would get a "sound" from the GPS box when we turned the key to the on position.

Roger Harper
2006 Intrigue
#11990

Re: small motor sound under dash

Reply #3 –
Yahoo Message Number: 84513
Bill,

Can't say for sure as to your coach but ours does have a small vacuum pump under the dash. It starts every time I turn the key on so I am guessing my system must have a small leak. The vacuum is used to control the dash heating and AC system.

Barney

07 Inspire 52059

Re: small motor sound under dash

Reply #4 –
Yahoo Message Number: 84516
Roger,

Coach does not have a built in GPS, we use a Garnin Nuvi on the dash.

Barney, Have tried to locate the pump, but there is so much clutter , just cannot see down low. Mine only comes on after setting overnight. When I stop for a rest time. on restart it does not come on.
Bill Dane 99 Allure 30326

Re: small motor sound under dash

Reply #5 –
Yahoo Message Number: 84517
Bill,

Mine is not actually inside the dash. It's mounted outside the coach in front of the dash. It's between the fiberglass shell and the front of the dash. This is a space in there where your wiper motor and the front part of the heater would be. Bunch of other stuff in there also. On mine I open the generator slide then climb in beside the generator in front of the passenger side of the coach. Then look up. It's very easy to get to...on my coach. Here's a picture;
http://www.moenracing.com/VacuumPump/
You might try looking up in front from under your coach. Hope this helps

Barney

07 Inspire 52059

Re: small motor sound under dash

Reply #6 –
Yahoo Message Number: 84518
Barney,

Man, you keep that area clean. In my coach, the generator is located in the first compartment on the driver side behind the front wheel. Will look again now that you have shown what one looks, thanks.

Bill Dane 99 Allure 30326

Re: small motor sound under dash

Reply #8 –
Yahoo Message Number: 84520
OK...now that we see it...what is it for????

Dave

07 Country Coach Allure 430 #31495 12 Jeep GC Toad Mountains of So Cal
Dave & Jodi
2007 CC Allure 40’ Tag #31495
2012 Jeep GC
Big Bear Lake, Ca & Henderson, Nev

Re: small motor sound under dash

Reply #9 –
Yahoo Message Number: 84521
I hope you are talking about the vacuum pump motor. On a gas engine , like in your car, the gas engine operates under a vacuum when the pistons draw the air and fuel in. The gas engine uses this available vacuum to open and close valve for dash, floor and defrost conditions on your dash fan. The diesel engine is at the back of the coach, so there is no readily available vacuum. Like in the really old days , you had vacuum operated wipers, which ceased to work when you stepped on the gas. The vacuum operates the valves which switch your dash air valves from floor to dash to windshield. They basically use old , available technology, in your over the road , dash controls. Since there is no readily available vacuum , they put a pump in that replicates what a gas engine does naturally.

Ron Baran 09 Magna 7025

Re: small motor sound under dash

Reply #11 –
Yahoo Message Number: 84607
Mine makes noise all the time. I suspect there is a leak so my pump constantly runs, unless I turn on the fan. I leave my vent running on low most of the time so the vacuum pump doesn't run. Don't know if that is the right thing to do. Just trying to keep up with the nit-picky maintenance issues and haven't reached that one yet.

Steve

2000 Allure #30550

Re: small motor sound under dash

Reply #12 –
Yahoo Message Number: 84611
Steve, I know what your problem is as I have the same thing. On the back of the heater/ac control panel, there is a manifold with some air lines on it. What is happening is the manifold either has a crack in it, or one of the little air lines is coming out or the attachment block is not sealing up the the control. The part is no longer available but you can seal up the leak with silicone sealant.

Don

'02 Intrigue #11427
'02 Intrigue #11427
 

small motor sound under dash

Reply #13 –
Yahoo Message Number: 84524
We call it a vacuum generator.

Dave Rousey Jr.

Former CC Technician
Styleworks RV/ Bus

Restoration LLC (owner)
4762 Long St.
Sweet Home, OR
(541) 543-7983
daverjr4@...