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I have a 95 sedan deville that the a\c stopped working in. A message on the electronic
dash is saying Very Low Refrigerant. A\C compressor off. My first thought was to add
more freon 134a. I had about 6oz left in a can so I added it . Still had the message. Maybe
what I had was not enough so I picked up another can in case most of the freon had leaked
out.
I had to fool the ambient switch because it is only 50 degrees outside by heating it up
with a hair dryer and this raised the temperature reading on the dash to read 112 degrees.
Also I put a heater inside the car to raise the temperature to 95 degrees. After adding about
half of the can the commpressor cycled on for about 3 seconds then off again. this happened
two more times then the message appeared again.

I checked the low pressure swtich on the side of the accumalator with a ohm meter and the
contacts are closed, so I know the switch is ok. I even jumpered this switch and the compressor
still did not turn on. After this did not work I thought I should maybe start over. I borrowed
a set of guages and a vacumm pump to recharge the system. I bled off the system and
pulled the vacumm for about 30 minutes until it reached -25hg, I turned off the pump and
the vacumm held fine for ten minutes. This time I used a bulk drum of freon. I started the car
turned the drum upside down and fed in 1 lb of freon. I let the car run for about 5 min while I
heated the ambient switch up and the inside temperature was about 95 deg. I turned on the
auto a\c switch with the temperature set at 65deg. The compressor still did not come on, so
I kept adding freon until 2 lbs was reached. Still no luck.

After this complete recharge I even checked all the fuses for the compressor and they
are all good. The fan blows air like it should ,no problems there. I picked up a Haynes
auto a\c book dated 2000 and read that a compressor cannot compress liquid freon only
vapor. But then in a section of the book for evacuating and charging a GM fixed orifice
system the drum should be inverted for the charge, seemed conflicting to me.

So now I decided to bleed the system again, pull down the vacumm, recharge the system
with the drum upright for gas. Before I started the charge I found a taped up splice conn
in the compressor clutch wire, thinking this could be a fuse I untaped it only to find a
small resistor or diode inside, it looked ok so I closed it and retaped it.

Back to the same routine fooling the sensors,adding 2 lbs of freon (gas) warming engine
switching on auto a\c and still getting message Very Low refrigerant, A\C Compressor Off.
Today still at a loss for what could be causing A\C not to come on. A Cadillac service man
at the dealership said the dash message should go away if the low side pressure is ok. It
is about 40 lbs at the accumalator without the compressor running.

Hope someone can help in diagnosing what could be wrong.
Thanks,
lampman
 

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1996 Deville Concours
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I may be making a schmuck of myself here... It sounds like you know more about recharging than I do :tongue2: , but it made me think a little. I've just seen a few compressors go a few ways, so I thought I'd stick them here just in case. First off, I'm pretty sure that refrigerant you're buying (R-134a) is not freon. I believe that was outlawed some-odd years ago because of its harmful effects on the environment...though it was much colder :cool: . Anyhoo, I presume with your vacuum gauge, it isn't a leak.... I've seen cases where the clutch simply won't engage...like being physically rough and not wanting to lock up. I'd get more detailed, but I'm afraid I'm not up on the more modern models... If it is belt driven, one of the pulleys could be out of alignment...but I would think that would just cause squeeking. If not (if that sort of thing even exists :hmm: ), maybe the motor is shot...as you had it running for a few seconds...then never again... Anyway, sorry if this seems obvious to you...but I've been cooped up here all day and I'm bored and stuff. Good luck anyhoo.
 

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I had the same problem on my '94 Deville about 3 weeks ago. (Like the last guy, it sounds like you know more about charging than I do.) What I learned off another listserv is that you have to fool the computer, which has switched off the compressor and won't turn it back on because of low refrigerant...and it now can't perceive that you have fixed the low refrigerant, since the compressor is off. A classic Catch-22.

SO...as I was told...I disconnected the battery for about an hour, hooked up the refrigerant to the system, reconnected the battery, turned the A/C on full-bore (set my temp to 60), and started the motor. This way the compressor turned on and sucked in the R-134a and oil, although I was suprised how long it took to empty the can I was using. I only added a small can, but it was enough to get the light on my dash turned off. :coolgleam

Perhaps it will be easier for me to get the system to pull in refrigerant when the weather gets warmer. Meanwhile, this is good enough for me.

Good Luck--

Paul Nagy
'94 "Maroon Moon"
Clovis, NM, USA
 
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