Still having AC trouble.

[98viperGTS]

Ok, so the Freon is not the problem. When I 1st start the car, in the garage and its cool, the air blows cool, not cold. Then if I drive it in the heat, of course, the air just can’t keep the cabin cold and feels like it gets warmer. What do I check next and how do I do it.

 

[AG98RT10]

Why do you say the Freon is not the problem? Sounds like it is.
Seals usually go where the lines fit the compressor, or back at the exchanger, I had to replace mine...

 

[98viperGTS]

I put a gauge on the low side for Freon and it was in the green.

 

[snampro]

does your compressor engage when the A/C is turned on? if not maybe the clutch is bad. if it does engage and it still isn't cooling you might have a bad compressor...its not unheard of

just some thoughts...

 

[Andrew/USPWR]

On a hot day the a/c will only keep one person comfortable. If the car is moving.




2005 Silver SRT/10
2000 Steel Gray GTS (sold)

 

[02 Graphite GTS]

I went on a run with the SoCal Viper group up to Big Bear over the weekend. SoCal temps were in the 90's. I had the AC on and noticed that if I were cruising at a constant speed the cold air was consistently cold. If I was on the gas pedal speeding up after shifting....it was like the AC compressor shut off and warm air came through the vents. As soon as I was back to a constant speed the AC air was cold again. Driving on city streets, signal light to signal light, the AC air never got super cold due to the fluctuation of warm air.

 

[PDCjonny]

On a hot day the a/c will only keep one person comfortable. If the car is moving.

Insert "barely" comfortable in there and I would agree...

 

[98viperGTS]

The air feels luke warm when driving. How can I tell if the clutch is engaging? The compressor was replaced last year. I would not think that would be it again but I dont know.

 

[PhoenixGTS]

I went on a run with the SoCal Viper group up to Big Bear over the weekend. SoCal temps were in the 90's. I had the AC on and noticed that if I were cruising at a constant speed the cold air was consistently cold. If I was on the gas pedal speeding up after shifting....it was like the AC compressor shut off and warm air came through the vents. As soon as I was back to a constant speed the AC air was cold again. Driving on city streets, signal light to signal light, the AC air never got super cold due to the fluctuation of warm air.

That is a lack of vacuum to the vent control under acceleration causing that. Apparently installing a check valve will solve the problem. There has been a bunch of talk regarding this issue in the past on this board. My understanding is that the baffle that moves and directs the cooled AC air in to the car requires continuous vacuum to hold it open. When you floor the car the vacuum of the engine drops to near zero and allows the vent to "fall" closed.

 

[pescadito]

I had this happen to me too and I found a fix last year on this forum. There is a simple fix.

The loss of cool air when accelerating is a loss of vacuum to a one-way valve behind the AC controls in the dash. If I remember correctly this valve keeps a vent closed. But when as you accelerate this causes a vacuum increase . The valve is too small or gets old to hold vacuum to keep the vent shut. An easy fix was to supplement the valve with another valve, which is a 5 sec fix.

There is a vacuum line located on the rear of the valve cover on the passenger side. I pulled the vacuum line and attached one side of the valve to the existing line and the other side to a short piece of 1/16 rubber tubing into the vacuum port. Problem fixed. Cold air all the time now. The proper way to fix this would probably be to replace the valve behind the AC controls but this is much easier and faster.

I don’t know if this is a permanent solution but I’ve had mine on since last summer and it still blows cold air on acceleration.

Here are the parts I got from McMaster-Carr
http://www.mcmaster.com/

Part # 47245K26
Diaphragm Check Valve, Nylon Body/Fluorosilicone Diaphragm, 3/16" Barb

Part# 51135K172
Silicone Rubber Tubing, Firm, 3/16" Id, 5/16" Od, 1/16" Wall, Black

 

[hemibeep]

okay,
some shade tree mechanic AC stuff.
1. you need the proper gauges to find out what is really going on. TRY harbor freight tools. around $55 for a 134 setup. this will give both high and low pressures.
I can't remember the high side pressure #'s but they are in the manual.
2. when you replace the AC comp, did they evacuate the system really well? A little moisture will really impact the system,
3. too much freon will make system seem hot.
4. do you have a temp gauge to check outlet temp? actually the AC will usually have the coolest output on MED fan speed. Set too fast, and the hot air rushes over the coils fast and doesn't cool well.
5. they sell kits to check for leaks at walmart. (DYE and special light/glasses.)

I would start with a good set of gauges and check high/low pressures to make a good assesment of compress and freon levels.

 

[Tom F&L GoR]

98ViperGTS, if you read the gauge when the engine and AC was off, the residual pressure may be in the green. However, when you turn the engine and AC on and the compressor comes on, it ***** R-134a into it. The gauge is on the suction side, so the pressure will drop, maybe below the green. If the pressure drops below the green, the pressure switch will open and turn the compressor off, which means no cold air.

Please report back on this experiment:
1) install gauge on suction side
2) turn engine on
3) have someone watch the gauge, and then
4) turn AC on. You should hear a noticeable "click"
5) No matter what, the pressure should fall some amount.

Normally, it will still stay in the "green" range, but may occasionally fall below that. When that happens, the compressor turns off (loud click) and the pressure will rise. When the pressure gets high enough, the pressure switch will close again, the compressor comes on again, the pressure falls again...

If you don't hear the click and don't see the pressure decrease, then the compressor is not coming on. If the pressure is in the green, you have enough system pressure that the compressor should have at least started, so I would then look for an electrical problem.

Good Luck.

By the way, I vote for the AC being pretty effective. My '94 has had a can added about every other year and works just fine. It's the same compressor as other Dodge vehicles, which have a larger cabin area to cool. Yes, I have cats which make the sills warm, but the air is cold enough to compensate.

 

[02 Graphite GTS]

Hey Phoenix and Pescadito...Thanks for the info. I'll be sure to get this done before the long drive through the desert to VOI9.

Good luck with yours 98vipergts.

 

[DEVILDOG]

I had this happen to me too and I found a fix last year on this forum. There is a simple fix.

The loss of cool air when accelerating is a loss of vacuum to a one-way valve behind the AC controls in the dash. If I remember correctly this valve keeps a vent closed. But when as you accelerate this causes a vacuum increase . The valve is too small or gets old to hold vacuum to keep the vent shut. An easy fix was to supplement the valve with another valve, which is a 5 sec fix.

There is a vacuum line located on the rear of the valve cover on the passenger side. I pulled the vacuum line and attached one side of the valve to the existing line and the other side to a short piece of 1/16 rubber tubing into the vacuum port. Problem fixed. Cold air all the time now. The proper way to fix this would probably be to replace the valve behind the AC controls but this is much easier and faster.

I don’t know if this is a permanent solution but I’ve had mine on since last summer and it still blows cold air on acceleration.

Here are the parts I got from McMaster-Carr
http://www.mcmaster.com/

Part # 47245K26
Diaphragm Check Valve, Nylon Body/Fluorosilicone Diaphragm, 3/16" Barb

Part# 51135K172
Silicone Rubber Tubing, Firm, 3/16" Id, 5/16" Od, 1/16" Wall, Black

Great solution...thanks!

 

[Travis]

Forget what you 'leared' here and go to www.autoacforum.com and get some expert from the pros.