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Old 01-23-2008, 04:10 PM
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J-Ri J-Ri is offline
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Re: AC/Heater Control Switch

The mode doors are vacuum operated. There is a vacum hose that runs in through the firewall on the drivers side. Disconnect it and check for vacuum. If no vacuum, start moving toward the engine. If it has vacuum where you check it, move towards the HVAC stuff. A common spot for the hose to crack is near the battery. The mode should default to the defrost position if vacuum is lost, so a door or actuator may be stuck.

The A/C not working is probably not related. Check the A/C line pressures. Check to see if the compressor clutch is cycling. If it is, check the temperature blend door. If it's not, see if it's being commanded on.
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'04 Cavalier coupe M/T 2.2 Ecotec
Supercharged 14 PSI boost, charge air cooler, 42# injectors
Tuned with HP Tuners
Poly engine/trans/control arm bushings
Self built and self programmed progressive methanol injection system
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