HVAC One Way Check Valve Issue?

[Matt M PA]

While driving today with the A/C on, in 6th, I accelerated to pass some other traffic without downshifting. This meant that the gas pedal was fairly well depressed.

I noticed that the A/C stopped blowing and the defrosters came on...then all went back to normal when the pedal was in cruising position again.

Does this mean that the one way valve needs to be replaced? I seem to remember reading that this was a symptom of that.

I looked at the right side of the engine where the service manual says to find the vacuum supply hose. My understanding is that this is the elbow on the rear of the passenger side intake. I see this hose, but I have followed it all the way to the firewall and there is no valve that I see. I also cannot find this valve in my parts book.

Also, would this part be covered by my 7-50 Max Care Chrysler warranty?

Thanks!

 

[PBJ]

Matt,
The check valve is inside the car behind the A/C head... it should be covered. There is a revised part from a Ram/Dakota that we have less problems with. There is a TSB on this problem , but I don't know the part number off the top of my head. It is a different style valve, but it works great. Hope that helps.
Later,
Joe

 

[Matt M PA]

Thanks PBJ, the only Tech I trust is 3 hours away (Hi Chuck), so this may be a job for me...is this part readily available?

 

[Mighty GTS]

Matt:

I've replaced the control head in my car twice searching
for an AC problem. Chuck helped me out with a free/used
controller. Its a piece of cake. Let me know if I can
be of assistance. Joe.

 

[Matt M PA]

Thanks Joe-I have no problem with taking the control unit out...but need to know where the valve is.

According to the post above..it is behind the HVAC dash unit. According to my memory (agreed..it's spotty) the service manual says it is under the hood.

If my diagnosis is correct that the problem is indeed this valve...I'd like to get one and replace it. If I need further diagnosis, I'd like to know where to start.

(I find it a bit hard to beleive that it is the control unit in the dash as my 94 Bronco and 03 Cobra use the same part and they work fine.)

Thanks!

 

[Mighty GTS]

It is indeed right behind the control head at least on my
97. If you removed the cowl and didn't see it engine
side, then its the same for yours. I looks kinda like
the black thing the Dr. puts on the end of the flashlight
when he looks in your ear, only smaller. You can probably
isolate the problem by installing one in the main vacuum line off the manifold, in the engine compartment. Much
easier to do, as you don't have to remove anything, but you
will have to cut the hard plastic line in the bay to insert
it.

My car does kinda the same thing under heavy throttle. The
engine vacuum changes at WOT and the default setting is defrost.

My vacuum leak was the recirc. door flapper actuator. It had a hole in it and would not hold the door open, and the
AC went to defrost at idle. Chuck hooked me up $22.00 for the part and 3mins install....excellent.