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Discussion Starter #1
I have 1994 LS, and my problem is that the compressor works fine, but every so often it engages and dis-engages a number of times, with the fan not active. Then it will engage again, and the fan wil activate and everythings works fine again. When I set the LCD control to LO setting the compressor appears to work fine. When it is set at anything above LO it will operate just fine and then it will go through this cycle again. I have changed the receiver dryer, the pressure switch, the resistor in the rad shroud, and the temp sending unit from the rad works at the posted setting. My question is could this be due to a fualty contact in the LCD control module?
 

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Is the Freon low, or overcharged? The pressure switch can cut out the compressor in either case. You may need to have the high side and low side pressures checked out by an A/C mechanic.
Charles
 

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Yep agree with Chazzy

When the temp is set to full LOW or full HIGH on the 94/95's, it takes the control system out of the equation (theoretically) and goes into open loop mode (ie if doenst care about reading the inside temp and making adjustments based on cabin temp) -- at least thats my recollection of the design. Always, the first step in troubleshooting any AC problem is to get a high and low side pressure reading, make sure you also measure ambient temp at the time as well, or at least have a decent estimate.

If the pressures are OK, I would wonder in the following order

a. Overhead console-- is the little fan that draws air over the interior temp measuring thermistor operating?
b. Trinary Switch
c. AC relay
The last thing I would suspect is the Climate Control Module, but it is possible that there is an issue there.

bob
 

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Discussion Starter #4
Thanks Guys

I have just echarged the system.I have replaced the trinary switch. The relay was cutting in and out before I changed the item I mentioned. I have not thought about the little fan for inside. How is the best way to test it?
 

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Pressures!

What are the high and low side pressures?

The little fan is in the overhead console, remove the cover there are two screws IIRC and you should be able to see it

I understand that you recharged the system. Can yougive us the high and low side readings?
 

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Discussion Starter #7
Hi the follow were the spec when I recharge it:
Humidity 48%
Temperature 76 F
High side max 96psi
Low side min 69psi
Charge weight 2,76lbs
 

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Hi the follow were the spec when I recharge it:
Humidity 48%
Temperature 76 F
High side max 96psi
Low side min 69psi
Charge weight 2,76lbs

Low Side Readings
(PSI)
16-29
Evaporator Temperature (Fahrenheit)
33-55˚F

High Side Readings
(PSI)
115-200

Ambient Temperature
(Fahrenheit)
70-80˚F

Jason
 

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Discussion Starter #9
Hi Jason

There sure a vast difference in the pressures. Do you have any suggestion in what is going on?
 

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There sure a vast difference in the pressures. Do you have any suggestion in what is going on?
Hi,

1. Possibly too much oil in the system, not enough oil?

2. Expansion valve.


Jason
 

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Not good pressures

Your low is way too high and your high is way too low

I wonder if you have a blockage somewhere -or your compressor is toast. Until you can get reasonable pressures there is no where else to look -- back to the basics=== Did you replace the receiver dyrer?
 

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Discussion Starter #13
Yes! I replaced it with one from the Saab, with an adaptor from Jason to fit a new trinary switch. Maybe that is not working.
 

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Your high side is way too low and your low side is way too high. If you are sure the system has 2.7 lbs then charge capacity is in the ball park. You have a restriction on the low side. I would check the expansion valve. If it is stuck ( common problem ) you will not get the proper flow through the system. Your description of it works and then does not work also reflects a bad expansion valve.

My S, when I bought it last year had the same problem. When the AC worked, it worked very well. Then it worked luke warm. The problem was someone had installed a screen in the expansion valve incorrectly and the screen collapsed - creating a partial blockage into the expansion valve. Replacing the expansion valve fixed system -performance.

Good Luck.
 

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Your high side is way too low and your low side is way too high. If you are sure the system has 2.7 lbs then charge capacity is in the ball park. You have a restriction on the low side. I would check the expansion valve. If it is stuck ( common problem ) you will not get the proper flow through the system. Your description of it works and then does not work also reflects a bad expansion valve.

My S, when I bought it last year had the same problem. When the AC worked, it worked very well. Then it worked luke warm. The problem was someone had installed a screen in the expansion valve incorrectly and the screen collapsed - creating a partial blockage into the expansion valve. Replacing the expansion valve fixed system -performance.

Good Luck.

LOW SIDE HIGH

HIGH SIDE LOW

CAUSE OF READING

COMPRESSOR NOT WORKING PROPERLY

WHAT TO DO

REPLACE COMPRESSOR & ACCUMULATOR

ADD OIL, EVACUATE AND RECHARGE

(Tip) Center Vent temp cool, Not cold

(Tip-2) On Variable Displacement Comp. Check Pressure Valve
 

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Discussion Starter #17
I do not know if I am any the wiser, I re-tested my a/c today, and here are the readings: three reading High side max pressure 168,169,171psi Low side minimum pressure 29,32,34. Red vent temp constant at 70F, blue vent temp 69F. The system blowes cold, but the compressor still cuts out sometimes. I have dye in the oil, and I see some leaking out on the compressor. I assume that the compressor is going. Can they be rebuilt?
 

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I do not know if I am any the wiser, I re-tested my a/c today, and here are the readings: three reading High side max pressure 168,169,171psi Low side minimum pressure 29,32,34. Red vent temp constant at 70F, blue vent temp 69F. The system blowes cold, but the compressor still cuts out sometimes. I have dye in the oil, and I see some leaking out on the compressor. I assume that the compressor is going. Can they be rebuilt?
Where do you see dye at clutch area? If so front seal is leaking and can be replaced. Search for my posts on replacing front seal and clutch pulley bearing. You will need seal and tools I list as well as new bearing (freon and compressor oil leaks can cause pulley bearing to fail).

Your pressures are about right on a cool morning. Warmer weather will bring low side up some and high side once up to about 200-215 which will turn on cooling fan to keep pressure under control and help transfer heat out of condensor.
 

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Discussion Starter #19
Thank Steve!
The oil is evident at the front of the compressor from the bottom. Where would I look for your post?
 

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