I was wondering if anyone else has had this problem before. I have a 95 Formula and have had a 93 Z28 and both cars had the same thing wrong w/them. When I'm in 5th or 6th gear (dosent matter) and I have my a/c or heater on and I start to go up an incline or hill the air cuts out and dosent blow out my vents for that time. Then when I get back on straight road it starts blowing out my vents again w/no problem..anyone know what the prob is ?

 

Well you have the proverbial vacuum leak that we all have to our HVAC controls. Took me 3 weeks to find mine. A little history is in order.

The HVAC controls default to defrost/floor. When all the vacuum is gone, the HVAC will blow defrost and floor, no matter what the temperature is set for. When you loose the vacuum to hold the HVAC doors to another setting, the system defaults or falls to defrost/floor. Check it out the next time you are driving and floor the throttle. You don't have to go up a hill to see it happen. When the vents cut off you can feel it at the defrost and floor position.

This may help
http://shbox.com/1/vac_check_valve.jpg

This is the vacuum check valve at the passenger engine side fire wall. If you have vacuum there the problem is most likely in the cockpit.

Check all the positions of the HVAC system. Mine turned out to be the hose came off the bi-level actuator. Everything work but the bi-level setting. When I was in any other setting, and I got on the throttle, the blower appeared to slow down until the engine speed settled down.

Good luck to you

 

Thanx man..this REALLY helps alot !!!

 

i had a little different problem, my vents just didnt work only my feet and defroster vents, then i went into shoeboxs website and looked for a vacuum leak and there it was, not it works great!!!!