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Dive in · 02-13-2020, 04:58 PM

Hi all - I'm looking for a little help tracking down an issue with the dash A/C on our 2006 Itasca Sunova. Everything seems to work fine until we turn it to "MAX A/C" at which times it starts blowing out the defroster vents by the windshield. If I turn it back to regular "A/C" setting it starts blowing fine out the dash vents again. I'm pretty sure this is a vacuum issue but I'm trying to track down where it is. I thought is was the switch on the dash where all the vacuum lines come together as when it was turned to max a/c it sounded like a vacuum leak within the switch itself. I replaced the switch, $30 at Ford dealer, but still have the same issue. I'm wondering if anyone knows what color vacuum hose controls the max a/c setting and where does it attach to so I can hopefully track it? Also, does max a/c draw cool air from inside the cab as opposed to regular a/c that probably draws in hot air from near the engine?

As always, thanks for your help!!!

Tom N · 02-13-2020, 05:27 PM

Dive in · 02-14-2020, 03:17 PM

Thanks for posting that Tom, it was very helpful! I ended up finding a spot on the green vacuum hose that was worn and had a good size hole in it. Luckily it was easy to get to, behind a rubber flap in the engine compartment, and easy to fix. Dash air working fine again!!

Tom N · 02-14-2020, 04:27 PM

I've posted this many times over the past 17 years. A simple diagram that is easy to understand. I think it has helped many. No one likes dash heat or AC problems.

-Tom, W3TLN

US1 · 03-01-2020, 07:19 PM

Tom, just wanted to say thanks for that diagram. While installing my airbags, I noticed a vacuum motor up under the passenger side dash in the engine compartment with just an 1" long blue hose connected to it. Found what I thought was the other end right at the firewall since it was the same color that appeared to have been cut off. I connected a vacuum gauge to that loose end but could never get any reading, regardless of where the heater selector, or temp dial was set. Figured I was up for an impossible task looking for a vacuum hose schematic, but in 5 seconds this popped up and its only days old!

Question for anyone that is familiar with my Winnebago dash heating layout..

In addition to the defroster vents, there are approx 4 round floor vents under the dash at our feet, plus 5 of the regular dash mount automotive style vents facing driver/passenger. I can not figure out those dash vents. Do they work with heat too or just A/C? When I select FLOOR, the round floor vents blow air, with very little coming out those dash vents. If I select MIX, both defrost and floor vents are blowing air, but as before the dash have very little air flow.
And DEFROST is just the defrost. Those dash vents dont appear to follow suit with the floor vents, nor can I get good air flow out of them. That leads me to believe they are for A/C use only?

ronnie_g · 01-06-2021, 01:09 PM

Thanks again for the diagrams....
I haven't resolved my problem yet. Had another diagram that had me thinking my vacuum switch was plumed wrong. This drawing appears to be what I have. Now just need to find the leak. My 3 stage motor never shuts the defrost off. W/o this diagram I would not have known that their were 2 lines to that unit. Now to find the leak.

Any suggestions on how to get to the red hose connection on the 3 stage motor. I tried looking up from the floor, everything is blocked. Even stuck a camera from above last night. But today need to find the red connection.

Thanks again for the help