1997 Dodge Ram Truck A/C Stops Blowing When I Accelerate

Reader Question: Good day to you sir,

I have two vehicles a 1997 Dodge Ram Extra Cab pickup 5.9 engine and a 1998 dodge Ram Passenger Van 3500 also 5.9 engine. They both have a common problem and no mechanic on the island can figure the problem.

The AC cools fine. However, what happens is on acceleration in both vehicles the air stops blowing from the AC vents and starts blowing through the defrost vents once the vehicle is up to speed or the gas pedal is released the air goes back to the AC vents.

Is there anything I can do myself to fix this. I am an AC and refrigeration technician. However, I am not familiar with vehicle AC. I am hesitant about trying to fix this, because I do not want to make a problem worst.

Thomas, Turks and Caicos islands

Hello my island friend,

It sounds to me like you have a vacuum leak somewhere. I would start the engine, raise the hood, and listen for a hissing vacuum leak noise coming from a broken rubber vacuum hose or a plastic connector.

If you do not see anything under the hood get inside the vehicle and listen and look under the dash for a hissing noise coming from an unplugged vacuum hose.

If you still do not see or hear anything, have your mechanic check the vacuum circuits for the engine and the AC duct works under the dash.

Blessings,
Austin Davis