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Discussion Starter #1
Ok this sucks. the 1994 3.8L tbird is not overendowed with power to begin with. However, an interesting problem has popped up.

When I step on the gas pedal too hard, the air conditioning stops coming out of the dash vents, and goes up through the defroster vents at the winshield. Now this sucks pansies, cause I gotta drive like I am 70 to keep the A/C flowin through the vents.

When I let off the gas pedal, it comes back through the dash vents.

I suspect a vaccuum problem somewhere, but know nothing about this system and where to start, Thanks for the help.
 

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You can usually hear a vacuum problem.... poke your head under the hood and under the dash with the car idling and listen for a sucking sound. If that doesn't do it get a can of starter fluid and start spraying it around until you hear the rpms go up. Probably don't have to tell you not to spray it too close to anything real hot....
 

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Discussion Starter #4
Ya, I don't believe there is a vaccuum leak, I am real familiar with those, no hisses, and rock steady idle.

What is a TSB, and where can I find the info???

Thanks again
 

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I'm Assuming

I'm assuming your not stomping on the pedal right?
I mean at WOT there is an A/C cut out relay that cut's off the A/C when at WOT.

BeirutsFinest
 

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True, but the A/C WOT cutoff doesn't also change the vents being used...
 

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You can see TSB titles at alldata.com but they want $$$ for the body text....
 

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well, my 3.8 does this when.......

i put the a/c on Max, now if i put it on normal my a/c will flow normal even if i stomp on the pedal, and the a/c still comes out cold so i dont worry about it. Try just putting it on normal and see if it does it.

Marvin M.
 

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Discussion Starter #10
I'll try that. I am not necessarily stomping it hard, anything halfway or more gets it to switch. I will try normal, but I use max because it is more fuel efficient, and recirculates cabin air
 

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yeah i know dude its a pain in the A$$

not being able to use the Max but hey normal work for me and it work good too.

Marvin M.
 

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Discussion Starter #12
Well, you know how it works. Today I can't use Max, tomorrow I can't use the whole damn car. I guess I shouldn't worry about the a/c when I am starting to get a vibration shifting into o/d, I wonder what that is? I think I here a new post.
 

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jeremy said:
Well, you know how it works. Today I can't use Max, tomorrow I can't use the whole damn car. I guess I shouldn't worry about the a/c when I am starting to get a vibration shifting into o/d, I wonder what that is? I think I here a new post.
Sounds like TC (Torque Converter) Shudder. Does it feel like your driving over train tracks? I would recommend reading this page of the tranny article or read the whole thing because it is a good one!!

If it is the TC, just simply try changing fluid to mercon V!
 

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Discussion Starter #14
Awesome, thanks for the link!! I am going to spend a lot of time reading that.

It exactly represents my prob.
 

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One way check valve

Your problem is fairly common. I am not aware of any TSBs on it, but here is what is happening. When you step on the gas pedal, your engine's vacuum drops off, reducing the vacuum "pull" in the system. This is not a problem, usually, what is supposed to happen is when you set the AC selector in a given position, there is a check valve that prevents the vacuum in the AC blend door actuators from loosing it's vacuum "charge" for lack of a better word. The door is spring loaded so that in the event of a broken vacuum line, it goes to the "defrost" setting, so you will have a defroster. When the vacuum is not pulling on the door, it moves to the defrost position. When you get on the gas, your vacuum drops, and with your one way check valve not holding the vacuum in the system, the door moves to defrost. I am not positive where it is, but I am pretty sure it is part of the AC selector in most of the Fords. Not a problem, you should be able to find a universal one way check valve, and install it on the line feeding your selector switch, and solve your problem.
 
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