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Dash Air Problem

Yahoo Message Number: 111494

My dash air works on NORM A/C. When I turn to MAX A/C there is no observable change and the vacuum pump in the bay under the driver area repeatedly cycles on and off.

Any direction from the group on troubleshooting would be very appreciated.


Dick May

2002 Intrigue, #11438

Re: Dash Air Problem

Reply #1
Yahoo Message Number: 111497

Since the vacuum pump runs continuously when you switch to max a/c the you may have a vacuum hose not connected to the damper that returns air from the coach to the cooling coils. Or, the vacuum hose may not be connected to the control manifold... On my 2000 Magna, the return vent for max a/c is at the bottom of the dash and I can use a flashlight and watch the damper door close.


2000 40' Magna CAT C-10, #5892

Re: Dash Air Problem

Reply #2
Yahoo Message Number: 111508

The 2000 Magna HVAC is a Specific Climate System unit. It may be different then what's installed in the Intrigue. On the SCS unit when you go to "MAX AC" it not only recirculates the inside air it closes 2 coolant valves to cut off the hot coolant to the heater cores. The valves are located on the left side of the unit and are operated by vacuum. The valves are only actuated when in "MAX AC."You can check them by applying vacuum to them. If they leak they would need to be replaced. You could plug the vacuum hose and use a ty-wrap to re-position the valve until you can get a replacement part.


2000 MAGNA 5766

Dash Air Problem

Reply #3
Yahoo Message Number: 111534

Dick, the only change in going from normal A/C to Max A/C is the fresh air vent closes so the air is recirculated. The vacuum pump running is a sign that it is trying to close the vent. If the cycling of the pump continues I suggest that you look for bad rubber vacuum lines or a cracked vacuum reservoir.

Good luck.

George in Birmingham(currently in Santa Fe) '03 Magna 6298

Re: Dash Air Problem

Reply #4
Yahoo Message Number: 111537

Hey Pete-

I had this same issue. When I put it in "vent" it would stop, so that is where I left it with the fan on low until I could get around to troubleshooting.

Underneath, I found the one vacuum hose that goes to the vacuum actuator to close the "outside" vent had disintegrated. At first I thought it might be the actuator, so I removed the hose and plugged it, and then the vacuum pump continued running, so likely not the actuator. When I traced back the hose, I felt by hand until I found the bad spot. I replaced that hose starting at the last good section underneath, and now the problem is fixed. My hose was white, and the bad spot was not readily visible by eye.

While I was at it, I added a air filter to my outside air intake. Not sure if this used to have anything on there or not. I could tell there used to be duct tape like someone had done something to filter, but it was no longer in place.

Hope this helps.  

Currently in Utah
CC Allure 36' #30443

Re: Dash Air Problem

Reply #5
Yahoo Message Number: 111552

Thanks to everyone for the tips. Since the Norm is working ok this will go near the end of my list.

It's not like it's hot here in Texas!


2002 Intrigue, #11438