Air condition not working properly

[awest]

The air-condition blows out the vents normally when driving unless I get on the gas pedal or the cruise causes the tranny to downshift. Then the cold air stops coming out the vents until the truck stops accellerating. 90+ degree trips are beginning to become unbearable with this constant on-again off-again air flow. Any ideas how to remedy this problem? I know the guys on this website can tell me exactly how to go about resolving this matter. Thanks in advance.

 

[RiverRat]

does air stop coming out the vents or does air still come out but not cold?

 

[Glacier991]

The PCM is programmed to cut out the A/C in high power (eg high acceleration kickdown type) mode. How hard are you driving this? Foot thru the firewall or just normal? The circuit that does that I'm not really savvy on... maybe someone else is..


Happy Exploring

Chris

 

[awest]

Air still blows but not cold and it comes from the defrost vent up by the windshield instead of the air-conditioning vents. Not over accellerating, just normal like going up incline on freeway or passing. Never to the floor or really hard.

 

[RiverRat]

Sounds like a plenum problem. Check for a vac leak between the ac control head and the engine. Also check the entire vac system. Mine did the same thing.

 

[awest]

The AC control head? What part would that be?

 

[RiverRat]

Originally posted by awest
The AC control head? What part would that be?

the vent control switch in the dash.

 

[Howard]

That sound very like loss of vacuum which moves the vents to screen only. There is a vacuum reservoir mounted on the plastic wheel arch liner on the passenger side. You have to drop the front of the liner to get to it. Looks like a big ball with two pipes going in. About 6" in diameter. Inside is a one way valve that is supposed to stop the vacuum going back to the engine when the pressure drops (like hard acceleration). You can test it by sucking on both pipes. One should let air through and the other should not. When I first got my x they had put the pipes on the wrong way round so the vents did not move at all (only screen). My guess is that the valve has failed. All the best.