A/C leaves the vents during acceleration

[TigeDuner]

I noticed when climbing a hill in our 2002 35U Adventurer that the A/C quit coming out of the vents until we started down the hill. I Had this same problem on our 87 Itasca on a Ford chassis. Is this comman for Ford chassis and is there a fix?

[TigeDuner]

I noticed when climbing a hill in our 2002 35U Adventurer that the A/C quit coming out of the vents until we started down the hill. I Had this same problem on our 87 Itasca on a Ford chassis. Is this comman for Ford chassis and is there a fix?

[TXiceman]

Typically this is caused by a leak down or pressure loss inthe vacuum system. There should be a vacuum canister under the hood and it should have a check valve on the engine connection side of the canister.

When yo uaccelerate, the manifold vacuum is reduced and if the check valve leaks, the vacuum in the canister is lost momentairly. With the reduced vacuum, the vacuum operated damper inthe A/C will switch their positions back to the normal position and the A/C vents will clos. Usually it will revert to the windshield defrosters.

So the place to start looking is at the vacuum canister and vacuum system.

Ken

[Joe-K]

Ken's suggestion is right on!

The vacuum is what keeps the dampers in the HVAC directional box sending the airflow to the correct vents in the rig. If you have a leak or a bad check valve, the dampers will go back to their resting positions,

If you can't find a leak, (although there probably is one) you may consider asking Ford about a auxillary vacuum canister that can be added to the system. Sometimes because of high load on an engine, there is very little vaccuum for long periods of time and an addesd canister can help.