the A/C DON'T cut off at WOT,Just the vaccum

luc

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the A/C DON\'T cut off at WOT,Just the vaccum

for all of you guys (and gals) that believe that the A/C cut off when you accelerate,to gain horsepower as some peoples think,I'm sorry to say that it is a VACCUM problem due to either a design flaw or DC being very,very cheap.

When you step on the gas,the intake manifold vaccum get very low and the doors/valves in the A/C/heater system just close.

Closed doors mean no airflow through the vents and as soon that you let off the gas,the vaccum go up again,the doors open and you get airflow again.


The A/C clutch cycle the compressor all the time in response to line pressure and/or temperature,even with the compressor off the A/C will still **** cold for a few minutes.

to solve this problem you have 2 solutions:

Good solution: buy a one way vaccum valve and put it inline on the hard plastic hose that is connected by a rubber elbow on the rear of the passenger side intake manifold (next to the windshield wiper motor)

Best solution: get a vaccum reservoir canister,disconnect the rubber elbow,run a rubber hose from the intake port to the "in" port on the canister and run another hose from the "out" port of the canister to the elbow that you previously disconnected.

With this mode,the heater/A/C will even work(move the doors/flaps)when the engine is off.

Luc.00GTS
 
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luc

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Re: the A/C DON\'T cut off at WOT,Just the vaccum

David,

I know that the clutch cut off at WOT,that's why I said that even with the compressor off,you still will get cold air for a couple of minutes.

Regarding the check valve.
Obviously this valve is not doing it's job,I did the canister mode on mine and I have cold air blowing ALL the time.
Try it and you will see.
The A/C vents not blowing has nothing to do with the compressor,the compressor regulate the temperature (simplified) not the airflow.
Do you think that when you are at WOT the blower is also cut off?
Luc.
 

RED97GTS

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Re: the A/C DON\'T cut off at WOT,Just the vaccum

The vacuum problem with the viper sounds similar to other Dodge products like my Ram.

TSB 24-01-96 Rev. A

1993 - 1997 (ZJ) Grand Cherokee
1996 - 1997 (ZG) Grand Cherokee (international Markets)
1994-1996 (BR) Ram truck

The vacuum supply to the Heater A/C System may drop when accelerating or when speed control engages. This may cause the mode vacuum motor to switch to the defrost position.

The fix is a check-valve.
 

Dixter

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Re: the A/C DON\'T cut off at WOT,Just the vaccum

Does anyone have a partnumber for the check valve and where
it should be installed on the car....
 

prodiver

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Re: the A/C DON\'T cut off at WOT,Just the vaccum

I have a 95 and had the same problem with mine. Changing the non-return didn't help but adding the vaccum canister took care of it. I think the canister cost less then the non-return. It is a Jeep part #53003408 and cost about $8.00. Very easy to set up.
 
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luc

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Re: the A/C DON\'T cut off at WOT,Just the vaccum

Ulysses,

sorry but I don't have a picture nor do I know how to post them

The vaccum reservoir canister is a DC part# 53003408,retail $12,for a Jeep and is a black plastic ball may be 4" to 5" diameter with 2 ports,has a check valve in it and a mounting ******.

I mounted mine just underneath the windshield washer bottle,using the ground bolt/stud on the frame to secure it.
Instead of using rubber hoses to connect it to the intake and A/C/heater system,I used a 1/16 hard plastic hose that you can get at any good performance shop (it is used to connect a mechanical oil pressure gauge)

As for a vaccum check valve,anyone that you can get at a part store will do.
It will seems that GEN1 cars need the canister and later car only the valve to work,but all years will work with the canister.

Luc.00GTS
 

KenH

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Re: the A/C DON\'T cut off at WOT,Just the vaccum

I misread your first post too, but now I understand what you meant. Sounds like a good fix for an annoying problem. Going on the TODO list of little annoying things about the car to fix.
 

GTS Bruce

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Re: the A/C DON\'T cut off at WOT,Just the vaccum

The only one that notices it is my wife.When at WOT I'm to busy to notice it. Bruce
 

rstoots

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Thanks guys for the info. Installed a $10 vacuum reservoir and air continues to **** when I punch it.
 

ViperJeff

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There is a lot of wisdom and help contained deep in the depths of these 1's and 0's
 

TalonTSi90

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No doubt, but most forums lose it when someone bumps a 4 month old thread let alone one like this :D
 

Bonkers

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I dont think anyone really has a problem with pulling out a
14 year old thread on this site... unless its like... "Did you
ever figure this out?" ... No... 14 years later and the car
still "______"... Those drive me nuts...
 

ViperJeff

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Promise, I won't lose it on those, however, I will close them
 

TalonTSi90

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I dont think anyone really has a problem with pulling out a
14 year old thread on this site... unless its like... "Did you
ever figure this out?" ... No... 14 years later and the car
still "______"... Those drive me nuts...

You usually find those on microsoft.com **** :)
 

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