1998 auto A/C

Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's, Olds 98 91-96, Buick Lesabres and Park Avenue 91-96. Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.
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Kevin Amstutz
SLE Member
SLE Member
Posts: 75
Joined: Sat Aug 01, 2009 3:16 pm
Year and Trim: 03 SSEI, 02 SSEI, 98 SSEI, 98 SSE, 98 SLE 98 SE
Location: Appleton WI

1998 auto A/C

Post by Kevin Amstutz »

My 1998 auto A/C will not power the compressor clutch. I have no blinking codes on the display and I swapped relays. At the A/C clutch relay, I have power at pin 30 & 86 which is fused power supply. I can get the clutch to engage when I jump pin 30 to pin 87. When will pin 85 get power to or from the PCM? It appears the PCM gets a signal from the pressure switch. Is there anyone that could help trouble shoot or explain the system in more detail?
Last edited by Kevin Amstutz on Sun Sep 26, 2010 6:21 pm, edited 1 time in total.
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TheEngineer
SE Member
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Posts: 13
Joined: Sun Aug 29, 2010 11:15 pm
Year and Trim: 1996 SE

Re: 1998 auto A/C

Post by TheEngineer »

Is there sufficient pressure in the system?
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gmman
Posts like an LG3
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Posts: 347
Joined: Tue May 27, 2008 11:48 pm
Year and Trim: 96 SE

Re: 1998 auto A/C

Post by gmman »

you may have the AC compressor that has a pressure transducer. i don't have access to a 98 FSM. i am posting how my 96 with ECC is configured. pins might not be the same. basically the transducer screws into the compressor and generates a voltage from 0 to 5 volts (5 volts is supplied by the PCM). the pressure transducer will supply a portion of that 5 volts depending on freon pressure in the system. my tests indicate about 2 to 4.5 volts for normal pressure. anything outside that and the PCM will disable AC clutch control relay. from your description of the problem, the AC clutch relay is not being energized so it appears the PCM is not supplying a ground to pin 86.

my problem was not freon pressure out of tolerance but the pressure transducer itself had failed. NAPA had replacement.

PS you will not lose freon when you unscrew pressure transducer. there is a shrader valve underneath pressure transducer. if you look down on the compressor from the radiator you will see the pressure transducer in the high pressure line. will have three wire connector.

so, this is just a guess as to how your model year energizes the AC clutch and you could still have freon pressure problems.


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Kevin Amstutz
SLE Member
SLE Member
Posts: 75
Joined: Sat Aug 01, 2009 3:16 pm
Year and Trim: 03 SSEI, 02 SSEI, 98 SSEI, 98 SSE, 98 SLE 98 SE
Location: Appleton WI

Re: 1998 auto A/C

Post by Kevin Amstutz »

Really nice diagram! My 98 FSM is pretty much the same. I have pressure in the system and I have 4.2V grey wire at the pressure transducer. I'm also thinking that the pressure transducer is bad. I will swap it out with my other Bonny tomorrow and see what happens. Thanks!
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Kevin Amstutz
SLE Member
SLE Member
Posts: 75
Joined: Sat Aug 01, 2009 3:16 pm
Year and Trim: 03 SSEI, 02 SSEI, 98 SSEI, 98 SSE, 98 SLE 98 SE
Location: Appleton WI

Re: 1998 auto A/C

Post by Kevin Amstutz »

Fixed! It was a bad pressure transducer. Thanks for all the help!
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