Vents cut out when accelerating

[GT40 2]

The air vents stop blowing and blow through the defrost. So I replaced the vaccum motor that controls the panel vents. But it still blows through the defrost. Does anyone have any idea what I should try replacing next?

 

[2BADSTANGS]

Check all your vacuum lines make sure there isn't a leak. If you dont find anything wrong there check the selector switch amd make sure it seals and changes as it should.

 

[RustBucket]

There's a vacuum check valve that's failed. I can't tell you where it is because I've yet to change one on a Mustang

 

[2BADSTANGS]

On my '93 Gt the vacuum valves are on the rear of the passenger strut tower.

 

[GT40 2]

What do the vacuum check valves look like?

 

[GT40 2]

I found some broken vacuum lines going to what I think is the check valve.

 

[2BADSTANGS]

Sounds like a step in the right direction, The vaccum check valves have two vac lines connected to them and 1 electrical connection there usually black and about 3in tall. Let us know if you get it fixed and what the problem was!

 

[Jimmy2Times]

GT40 2, did you find the problem? If so what/where was it? I'm having the same problem and so far have not been able to isolate the vacuum leak other than to verify that it's somewhere behind the dash, not under the hood.

 

[GT40 2]

I replaced the vacuum thing on the right strut tower today, but it didnt fix anything.

 

[2BADSTANGS]

Does this problem only occour during acceleration, or if you let the car idle and warm up without accelerating will it still happen?

 

[GT40 2]

It only happens during acceleration.

 

[glowstang93]

That thing you replaced on the right strut tower is the EVR or Egr control valve, the computer tells it when to open or not. Of course it is upside down in the pic, lol.

 

[GT40 2]

My EVR looks different from that one. What does the check valve look like?

 

[Mustang5L5]

Is the A/C on when this happens?

 

[GT40 2]

Is the A/C on when this happens?

It doesnt matter, A/C on or off.

 

[2BADSTANGS]

Check out #58 on this page, I know this is a 5.o, but yours should be in relatively the same place. CJ Pony Parts - Ford Mustang Parts

 

[GT40 2]

Mine has a vacuum thing there too.

 

[GT40 2]

So I replaced it with another one I got from the junkyard, and it didnt fix anything.

 

[GT40 2]

3. Vacuum Storage Canister - Stores Vacuum to prevent interruption of services during wide open throttle

Could that be the problem?

 

[2BADSTANGS]

It is definately possible. Have you checked the system for leaks? Sounds dumb, but you could pull vacuum lines and suck on them until you find one that dosen't hold pressure well, then inspect it. (If you dont want to anty up the cash for a real tester.) I think the vacuum canister is in the pass. fender. (Don't quote me on that though.) Also try the "stupid" test on the vacuum line going through the firewall near where the heater core hoses connect, because thats the one that provides vacuum to the vent selectors. If it's good, chances are youre problems elsewhere. Let us know what you find, 'cause this could happen to us someday.