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99 Cadillac Eldorado
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Discussion Starter #1
I have a 99 Eldorado and the A/C light came on. The compressor won't run now, guessing that is tripped off as a protection measure since the freon is too low. I'm using a freon can (134a), but the system won't accept it. Yes, I am hooking it up to the low side. I think I need to get that compressor to trip back on for the system to accept the freon. I was wondering if there is a procedure to bypass the compressor automatic shut down? I want to run the compressor to get the freon into the system. It's possible that I'm completely off base on all of this btw, if so please tell me. If not then please tell me the procedure to turn the compressor back on. Thanks in advance!
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,824 Posts
I have a 99 Eldorado and the A/C light came on. The compressor won't run now, guessing that is tripped off as a protection measure since the freon is too low. I'm using a freon can (134a), but the system won't accept it. Yes, I am hooking it up to the low side. I think I need to get that compressor to trip back on for the system to accept the freon. I was wondering if there is a procedure to bypass the compressor automatic shut down? I want to run the compressor to get the freon into the system. It's possible that I'm completely off base on all of this btw, if so please tell me. If not then please tell me the procedure to turn the compressor back on. Thanks in advance!
======================

have you found and fixed the leak-

how much freon is still in the system -

how much are you going to add -

do you need to add oil - how much -

what are your current pressure readings -
BOTH high side and low side -

have you cleared the codes -
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,778 Posts
High and low side pressures mean nothing if he can't get the compressor to run.

There's a specific charging procedure - in the service manual. You do a bypass on either a high side or low side pressure sensor to "fool" the system into starting the compressor.

Get a real GM/Helm service manual hard copy set from eBay or take out a subscription for your car on www.alldatadiy.com
 

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White Diamond '03 DHS (with DTS floor shift)
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87,173 Posts
I think I need to get that compressor to trip back on for the system to accept the freon.
Correct

I was wondering if there is a procedure to bypass the compressor automatic shut down? I want to run the compressor to get the freon into the system.
When the system detects low refrigerant it trips a low refrigerant message, sets a DTC and disables the compressor. Clearing the DTC will enable the compressor long enough to add refrigerant.
 

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Registered
99 Cadillac Eldorado
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9 Posts
Discussion Starter #5
Thanks for the response guys. I'm reasonably handy but I don't have gauges and all that. I'd get a subscription for the car but it's being sold soon. My mom asked me if I could top off the freon to hopefully get the A/C working before she tries to sell the car, I figure it's a worth a shot.

Ranger, it sounds like you know what I'm talking about all though I don't know what a DTC is :), but I gather I need to clear that and if somebody could tell me how to that'd be awesome!
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,824 Posts
Thanks for the response guys. I'm reasonably handy but I don't have gauges and all that. I'd get a subscription for the car but it's being sold soon. My mom asked me if I could top off the freon to hopefully get the A/C working before she tries to sell the car, I figure it's a worth a shot.

Ranger, it sounds like you know what I'm talking about all though I don't know what a DTC is :), but I gather I need to clear that and if somebody could tell me how to that'd be awesome!
=======================
for DTC - Diagnostic Trouble Codes - read this -
http://www.cadillacforums.com/forums/cadillac-deville-1985-2005-including-1985/138257-how-pull-codes-dtcs.html

My mom asked me if I could top off the freon
how are you going to do this -
and how much freon are you planning on using
 

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99 Cadillac Eldorado
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9 Posts
Discussion Starter #7
Thanks, I will check out that link.

I have one of those cans you get at the auto parts store, I have a connector that connects it up to the low side. I don't know how much I'll use to be honest.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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87,173 Posts
If the system is low enough to disable the compressor you'll probably be safe adding one can. The link Bass provided will tell you how to clear the codes (DTC's).

Have the can connected and ready to go as soon as you clear the codes and turn on the A/C. Wait too long and the code will reset.

DO NOT use a can that has a sealer in it. :tisk:
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
Joined
·
19,824 Posts
High and low side pressures mean nothing if he can't get the compressor to run.

There's a specific charging procedure - in the service manual. You do a bypass on either a high side or low side pressure sensor to "fool" the system into starting the compressor.

Get a real GM/Helm service manual hard copy set from eBay or take out a subscription for your car on www.alldatadiy.com
================================
High and low side pressures mean nothing
if he can't get the compressor to run.

actually - static pressure DOES help diagnose the problem -
if nothing else - it will tell the difference
between a completely empty system -
and one that is just low -
 
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