Air Conditioner Vacuum Doors Close with Acceleration
Jeep Cherokee, A/C Vacuum Doors Close with Acceleration Q: Its 1988 Jeep Cherokee with a 4.0 engine. The problem is with the air conditioning doors changing position to vent upon acceleration. The engine and accessories feel good and are running great cruising down the road, except during acceleration. When the engine drops the vacuum level, the A/C unit controls lose vacuum supply and the doors shift to their neutral positions. When we reach cruising speed with traffic, the vacuum comes back in and pulls the doors to the intended position to get that good cold air back in your face. We've visually checked the main vacuum lines from the intake manifold port through the reservoir under the front bumper up to the firewall. Thought I would ask if this is a recognized problem before I bend over and go through the dash, emissions lines or 4X4 systems. A: If the vacuum lines and vacuum reservoir are not damaged, you have a sticking or missing check valve in the vacuum supply to th...