snootalope

2002 ZR2

Yesterday it started with a somewhat overheating problem. I replaced the thermostat and that appears to be ok now.. However, now I can only get air (both cold and hot) from the vents. I swtich it to Floor, Defrost, or even the Vent only and I can hear this hiiisssssssssssssssssssss'ing sound that doesn't stop till I turn the **** to OFF. No matter what I do though, the air ONLY comes out of the vent? I can make the temp of the air change and that works just fine, whether it's the heater or the air conditioner, but still only out of the vents and it constantly makes the hissssssssssssssssss'ing sound until I turn the fan dial to off.

huh? Any ideas?

autopilotoff06

I asked my mechanic about that hisssing sound because my blazer makes the same. He said something about its a vaccum system and thats a normal sound. As for the air only coming from the vents sounds like another problem.

twizzle12

Sounds like you have a vacuum leak somewhere in the control system. Try to hear where the hissing sound is coming from and it should get you close to where the problem is. Either that or something is stuck in the door that moves to change it to the different locations.

snootalope

After checking every vacuum pump/actuator I kept going back to the actual switch that made the vents change (the selector on the dash). I took Friday afternoon off from work and went to a couple of junkyards and found the same switch (the selector on the dash) from a destroyed ZR2 blazer. Put it in and problem was gone. Part was only $10.

Thanks for the advice those guys!

blzn90

you have a vacuum leak somewhere most likly up under the dash. I have two s-10 blazers and have had many Blazers and s-10's over the past 15 years with the same problem.
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