Losing engine A/C upon Acceleration
I am having Engine A/C problems on my class A motor home Rexhall Aerbus. Stops cooling at higher RPMs and returns to cool air upon on deceleration. The following issues have been checked and resolved:...
Forum Discussion
This IS a lack of vacuum. Things to do on Gas chassis that use vacuum to operate the dash blender doors. ALL Class A Dash Vacuum systems have small leaks in the motors and on hard acceleration (engine goes to zero vacuum) the Vacuum reservoir is depleted of the extra vacuum and the controls revert to the Defrost vents. To verify this is your problem is simple. Put some paper towels on top the dash windshield defroster vents and then test drive. When on hard acceleration, IF the loss of vacuum is your problem the paper towels will blow off the defroster vents.
1. Install a 2nd vacuum reservoir to have 2
2. Install a 12 volt vacuum pump like on diesels and bypass the engine vacuum supply---THIS is the BEST repair but does cost money
3. Live with it as it is an annoyance but when you reach cruise speed the vacuum returns.
4, You never loose cooling at the evaporator, the cold air just comes out the defroster vents until vacuum is restored.
5. This has been an issue for over 35 years on Class A gas motorhomes with vacuum controlled blend doors
6. Motorhome chassis do NOT have a Compressor kick out switch on hard acceleration. Besides, IF it did, it would NOT cause lack of air out of the dash AC vents. You would still have air output. Doug
1. Install a 2nd vacuum reservoir to have 2
2. Install a 12 volt vacuum pump like on diesels and bypass the engine vacuum supply---THIS is the BEST repair but does cost money
3. Live with it as it is an annoyance but when you reach cruise speed the vacuum returns.
4, You never loose cooling at the evaporator, the cold air just comes out the defroster vents until vacuum is restored.
5. This has been an issue for over 35 years on Class A gas motorhomes with vacuum controlled blend doors
6. Motorhome chassis do NOT have a Compressor kick out switch on hard acceleration. Besides, IF it did, it would NOT cause lack of air out of the dash AC vents. You would still have air output. Doug
