Dash vents/AC blowing heated air

[stork08]

I have an '03 Itasca Sunova 30B on an F53 chassis. I am challenged with a dash ventilation system that blows warm air if the RV is idling at a standstill or traveling at low speeds. Once I am traveling at highway speeds the ventilation aproaches near-ambient temperatures. When operating the A/C, this condition can easily overcome the A/C's ability to blow cool air. I took the RV to the Ford dealership where they first measured the temperature of the air at the dash, told me it was normal and sent me home. Later the A/C stopped working and the dealer replaced the compressor under warranty.

I assume that the coolant water valve is not closing completely and thus challenging both ventilation and A/C. Has anyone experienced this? Any ideas?

Kent
Carlsbad, CA

 

[afchap]

Most Ford systems I am familiar with have a manual valve that shuts off the hot water flow through the heater. It is operated by a cable from one of the dash controls. Perhaps it is not properly closing. The valve should be relatively easy to find ...it will be in one of the coolant heater hoses running from the engine to the cab heater. Another possibility, I believe the vents are controlled by vacuum triggers. If there is a loose/leaking vacuum line or some other problem in the vacuum system, the appropriate vent flappers may not be closing properly. The fact that the condition improves some at highway speeds points to a vacuum problem as a real possibility.

 

[Wizard46]

On my last trip to Florida back in October, while going down, I could only get hot air from the dash vents. Finally just turned it off, started the genny and ran the roof air.
We stopped about half way down, I looked under the hood and think I saw the vacuum actuator on the blower housing. Don't know how to get to it to work on but I jiggled the vacuum connection trying to figure a way.
When I started back down the road, everything was working, maybe the door was stuck and only needed a little assistance. I'm dreading the day it stops again and I have to dig deeper. BTW, the actuator was on the bottom of the blower assembly above the tire.

Good Luck with yours.