4WD ENGAGES AND DISENGAGES ERRATICALLY / AC BLOWS DEFROST VENT ONLY
 

I HAVE A 1995 4 DOOR 4WD BLAZER AND THE 4WD BEGAN TO DISENGAGE AND ENGAGE ERRATICALLY WHEN I TRY TO USE IT. ALSO THE AIR CONDITIONING STARTED TO WORK STRANGE AT THE SAME TIME. IT BLOWS MOST OF THE TIME THRU THE DEFROST VENTS AND AFTER A FEWS MINUTES IT STOPS COOLING(THE CLUTCH IN THE AIR COMPRESSOR DISENGAGES) I THOUGHT IT WAS A RELAY AND REPLACED ALL THREE OF THEM BUT IT DIDN'T FIX IT. THEN I THOUGHT IT WAS RELATED WITH VACUUM BECAUSE BOTH PROBLEMS BEGAN AT THE SAME TIME AND BOTH SYSTEMS USE VACUUM. I DON'T KNOW WHERE TO START CHECKING IN FIRST PLACE. I WOULD APPRECIATE ANY ADVISED ON THIS MATTER. THANKS A LOT GUYS!

RE: 4WD ENGAGES AND DISENGAGES ERRATICALLY / AC BLOWS DEFROST VENT ONLY
 

If here's a vacuum reservoir (about the size of a large orange) on the underside of the hood in front of the driver, check the vacuum hose running to it. Loss of vacuum there will prevent 4WD from engaging in my 1997 Blazer - yours may be the same.

RE: 4WD ENGAGES AND DISENGAGES ERRATICALLY / AC BLOWS DEFROST VENT ONLY
 

I'd be willing to bet money you have a vacuum leak, and the reason it's kicking off the compressor is the evaporator is freezing up because there's not enough air flowing over it. Check all your hoses WELL.. hell just spend 20 bux (if that) and get all new and run 'em...



Aqua