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Suspect Evaporator Freezing up

knightgang on Tue July 28, 2009 9:06 PM User is offline

Year: 1997
Make: Oldsmobile
Model: Cutlass Supreme
Engine Size: 3.1
Refrigerant Type: 134a
Ambient Temp: 90
Country of Origin: United States

I posted earlier about the water leaking from the Airbox. After further inspection and talking to my wife about how the car cooled during her errands today, she said that it stopped cooling well and my kids in the back seat rolled their windows down. I suspect that the evaporator is freezing up.

I messed with the car a little earlier this evening. I put the A/C on max cooling and it seemed fine for a little while, then while driving it around the neighborhood, it was blowing moisture out or all the vents. I pulled back in the driveway, opened the doors and flipped the heat on max and watched. After about 30 seconds, there was a continuous drip of water from the evaporator box. I will be able to post pressures tomorrow after I get my new gauges delivered.

I have been doing some reading on here and I want to ask could this be caused because the Compressor Pressure switch is bad? If so, is this the part that I need.

https://www.ackits.com/pc/29-30095/Oldsmobile97Supreme3-1/29-30095+-+Switch+-+Pressure+in+Compressor

Additionally, is it possible that this could happen from a slightly over charged system or a faulty TXV or OT? Which does this car have?

Thanks. Will post back with pressures tomorrow, in the meantime give me your ideas. If you want more info, please ask, I will provide what I have...

GM Tech on Tue July 28, 2009 10:27 PM User is offline

Gotta watch those W cars-- they use a nipple on the drain tube- which plugs easily-- I always cut the end of nipple off-- (no other GM cars use a nipple- only w-car) a good set of pressure readings will confirm any freeze-up concerns-- anything less than say- 27 psi or so is susceptible to freezing- and yes two things can cause it with a V-5 compressor- a faulty control valve (rare) or air in the system- did anyone charge it without pulling a good vacuum first?? addiing charge allowing air in perhaps???

You have an orifice tube/ A/D system-- no TXV.....

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

knightgang on Tue July 28, 2009 10:35 PM User is offline

Thanks GMT. I charged the system myself. Pulled a vacuum for about 30-40 mintues. However, I did not have a gauge set that would measure the amount of vacuum. I will have my new gauge set tomorrow so I can give you pressures. I just hate that everythime you want to hook up gauges, you have to remove the intake airbox as the service ports are almost underneath it.

The car has about 165K miles on it. All of the A/C system is original as far as I know. This car had a blown intake gasket and sat in my driveway for about 18 months with the top of the motor apart. I do not know if it is possible that with the A/C system sitting up for so long and having leaked out all of its refridgerant if that could be a factor to cause the pressure switch to be faulty...

GM Tech on Tue July 28, 2009 11:15 PM User is offline

It can be done without removing the air intake-- I do it all the time

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

knightgang on Tue July 28, 2009 11:28 PM User is offline

You must have small hands!!! I can do it, but is a royal pain. Easier to remove the box while troubleshooting. For just a pressure check, I would fight with the box.

knightgang on Wed July 29, 2009 5:57 PM User is offline

Okay, got my new gauges today and checked this out. Ambient about 75 deg. Low 27/High 85. Also, i found dye around the center of the compressor indicating a possible belly leak. So I guess, I new compressor it is going to be.

Now, I know that with changing a compressor, I will need to also change the accumulator and the OT. I need to locate the OT. Also, I will need to flush the system.

Do I need to disassemble the lines and flush each component seperatly, or should I just flush from the accumulator and compressor lines.

Then, I know I will need to pull a vacuum and add back the proper weight of 134a.

Sound about right...

Chick on Wed July 29, 2009 7:41 PM User is offlineView users profile

The O tube should be between those service ports and the evap, under the brake booster I believe, should see the fitting there... If you didn't have a catastrophic compressor failure you may not have to change the accumulator, although it's cheap insurance, most failures on V5 compressors are just leaks... So a flush may not be needed unless the O tube shows a lot of debris and discoloration of oil.. Hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

knightgang on Wed July 29, 2009 9:23 PM User is offline

Thanks Chick. No, not a catastrophic failure. Compressor will still run, just will not get cold due to low pressure because of the leak.

How hard is it to rebuild one of these compressors? Do you need alot of expensive (special) tools? I need to get this car cooling quickly with as little money out as possible.

Chick on Thu July 30, 2009 6:48 AM User is offlineView users profile

If your compressor is leaking, it would be easier for you to put a reman compressor on the car rather than try to rebuilt it. Takes special tools and of course the O rings and seals. change the compressor, then pull a deep vacuum and recharge..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

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