why does the a/c stop blowing thru the front vents and comming thru tha defrost vents

Asked by j41053 Jul 21, 2013 at 05:45 PM about the 2001 Dodge RAM 1500 SLT Quad Cab 4WD

Question type: Maintenance & Repair

When I accelerate wwith the air on it stops blowing thru thefront vents and sterat blowing
thru the defrost and when you let off the accelerator the the air starts blowing thru the
front vents like it should.  Please help. Thanks.

8 Answers

199,845

Could be a vacuum issue. Some air diverters in the duct work are vacuum controlled. Not sure if yours is but if it is that's where I would look first.

15 people found this helpful.
199,845

Yes vacuum is supplied to the air control assembly by tubing to the intake manifold. Inspect the vacuum line for leaks and cracks. There is also a check valve in that line. (Note direction of check valve before removing it for testing) Apply 8 inches of vacuum, with hand-held vacuum pump, to engine side of check valve. You should be able to pull air thru the valve. Apply vacuum to air control side of check valve. The valve should hold vacuum. If not replace the check valve.

16 people found this helpful.
199,845

Check valve is connected to intake manifold with black vacuum supply line.

17 people found this helpful.
190

I have a 1997 Ram 1500 and dandyoun is 100% correct. My face vents would blow until about 1/3 throttle and then they would shut off until I backed off of the gas pedal. My check valve was located on the passenger side with a 90° elbow that connected it to the intake manifold just to the rear of the pcv hose nipple. I could blow air through it in both directions so I cleaned it with Brakeclean and it is working perfectly again. Problem solved. Thanks dandyoun!

19 people found this helpful.
170

it's probably the vacuum line going into to the cruise control servo. it's located under the battery. mine was doing the same thing. i looked at the vacuum line going into cruise control servo and it visually looked good. when i grabbed it ...it fell off in my hand. removed broken end and reinserted the vacuum line into the rubber elbow and bingo... it fixed my a/c problem and my cruise problem. hope this helps

17 people found this helpful.
100

Did this happen to effect your truck's ability to fire up at start, by chance? Did it happen to sputter and act like it didn't want to start for a good 5-10 seconds?

10 people found this helpful.
150

My 2000 ram 1500 was doing the same thing, checked all vacuum lines inside and out, finally found a cracked line leading through the top of the firewall right behind hood seal

15 people found this helpful.
20

Why ac stop blowing when accelerating in my truck2000didge ram 3604x4

2 people found this helpful.

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