98' S-10 Air Conditioning problem? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

70c10 · 05-30-2009, 11:33 AM

My AC is acting up. I've owned this truck for 3 years now. The former owner installed a new compressor right before I bought it. I checked the low pressure side fitting and I'm fully charged with freon. I checked the fuses and relays and they are good. What would cause the compressor to NOT engage "sometimes"??? Today it's working great

The engine is the 4.3

70c10 · 05-30-2009, 11:44 AM

I forgot to add, I've noticed the problem only on really humid days. Is there a sensor that detects humidity that would cycle the compressor on and off???

Arad68 · 05-30-2009, 04:57 PM

The high side pressue would make it do that too. (To much head pressure) I don't think there is a sensor that senses humidity.

corn · 06-01-2009, 01:10 PM

My 96 does the same thing, but only if I dont use it all the time. Mine has something to do with the wiring plug on the pressure cut off switch on the accumulator. If I unplug it & plug it back in, it will sometimes go. If not I jump the leads & it will take off. Hows that for backyard repair?

gchemist · 06-01-2009, 07:59 PM

Was a new high pressure switch installed on the new compressor? If jumper the compressor at the low pressure switch, you can determine which switch is not kicking on the compressor.

70c10 · 06-02-2009, 10:02 PM

I have no idea if a new switch was installed. How do I jump the switch and where is it located? Thanks

Andy4639 · 06-03-2009, 08:13 AM

Look at the acumalator, the round chrome looking cyclinder there should be a wire connected to it. Take the wire loose and jump it. This should turn the compressor on and off when hooked up. The only problem with it jumped is it runs all the time. The switch may need to be replaced it keeps from burning up the compressor, if the pressure gets to high or to low it cuts off.

70c10 · 06-04-2009, 10:01 PM

Andy, by jumping, do you mean bypass the switch somehow??? Do I run 2 leads to my battery from the accumalator?? If so does it matter on + and -? Thanks

corn · 06-04-2009, 10:13 PM

Pretty sure you just need a paper clip or jumper wire between the two connector wires.

70c10 · 06-05-2009, 06:35 AM

Thanks corn! So far it's been working fine but maybe the switch is going to go up this summer. No biggie, it should be easy enough to fix.

robin58 · 06-05-2009, 11:27 AM

Sometimes the clutches start to go on these compressors. Gently tap it and see if it kicks in.

68C15 · 06-11-2009, 06:39 AM

FYI, a system with a 10% charge will have correct pressures at rest. but once activated it will run down the low side fast and kick off. since the refrigerant carries the oil to the compressor a low charge will destroy the comp., fill the condensor with debris, coat the inside of lines and evaporator with "black death" reducing system efficiency, and plug the orifice tube screen.

make sure the system is full with the correct charge by weight, NOT PRESSURE

Andy4639 · 06-13-2009, 03:15 AM

When I posted about jumping it out Corn was correct the wire connection just make a loop in it with a jumper or paper clip. The pressure is a quick idea if something is wrong but the right amount of referangent is the best way to tell.

70c10 · 07-17-2009, 07:08 AM

UPDATE- the AC has continued to work intermittantly for the last month even though it "mostly" works. Yesterday I noticed when I stomp on the gas pedal to downshift the transmission it will kick ON the compressor and then the AC works fine. I always thought the WOT sensor or TPS is supposed to shut OFF the compressor when you downshift. Basically it's acting the opposite of the way it's supposed to

. So now I'm thinking a sensor on the the throttle body needs cleaning or replacing. Am I on the right track???

68C15 · 07-17-2009, 07:17 PM

the ECM turns off the compressor during WOT by deactivating the clutch relay. if the TPS was acting backwards you would be asking about severe driveability issues instead. after re-reading your posts i am wondering if the ECM is recieving a constant request from the control panel (bad switch on dash). it sure wouldn't be the first time I seen a bad HVAC control panel on a late model GM.

of course as luck would have it I am now home for the weekend and not at work. if someone (CORN) could remind me on Monday I can check to see which wire sends the AC request signal to the ECM. then I could post that and you can check for an intermittent open. hint-hint larry

05-30-2009, 11:33 AM	#1
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	98' S-10 Air Conditioning problem? My AC is acting up. I've owned this truck for 3 years now. The former owner installed a new compressor right before I bought it. I checked the low pressure side fitting and I'm fully charged with freon. I checked the fuses and relays and they are good. What would cause the compressor to NOT engage "sometimes"??? Today it's working great The engine is the 4.3 __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads Last edited by 70c10; 05-30-2009 at 11:33 AM.

05-30-2009, 11:44 AM	#2
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Re: 98' S-10 Air Conditioning problem? I forgot to add, I've noticed the problem only on really humid days. Is there a sensor that detects humidity that would cycle the compressor on and off??? __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

05-30-2009, 04:57 PM	#3
Arad68 Trucks N Tranzams Join Date: Dec 2002 Location: North Las Vegas, Nevada Posts: 816	Re: 98' S-10 Air Conditioning problem? The high side pressue would make it do that too. (To much head pressure) I don't think there is a sensor that senses humidity. __________________ Don '68 Chevy LB 383 TH400/GV/373 posi '56 Chevy 4WD SWB '64 Chevy short stepside '79 Trans Am 455/TH2004R/12blt/4whldisc 95 Kia (Wifes car) 2002 S-10 extended cab pickup "God punishes small sins immediately"

06-01-2009, 01:10 PM	#4
corn Registered User Join Date: Dec 2003 Location: here Posts: 5,789	Re: 98' S-10 Air Conditioning problem? My 96 does the same thing, but only if I dont use it all the time. Mine has something to do with the wiring plug on the pressure cut off switch on the accumulator. If I unplug it & plug it back in, it will sometimes go. If not I jump the leads & it will take off. Hows that for backyard repair?

06-01-2009, 07:59 PM	#5
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	Re: 98' S-10 Air Conditioning problem? Was a new high pressure switch installed on the new compressor? If jumper the compressor at the low pressure switch, you can determine which switch is not kicking on the compressor. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

06-02-2009, 10:02 PM	#6
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Re: 98' S-10 Air Conditioning problem? I have no idea if a new switch was installed. How do I jump the switch and where is it located? Thanks __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

06-03-2009, 08:13 AM	#7
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: 98' S-10 Air Conditioning problem? Look at the acumalator, the round chrome looking cyclinder there should be a wire connected to it. Take the wire loose and jump it. This should turn the compressor on and off when hooked up. The only problem with it jumped is it runs all the time. The switch may need to be replaced it keeps from burning up the compressor, if the pressure gets to high or to low it cuts off. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

06-04-2009, 10:01 PM	#8
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Re: 98' S-10 Air Conditioning problem? Andy, by jumping, do you mean bypass the switch somehow??? Do I run 2 leads to my battery from the accumalator?? If so does it matter on + and -? Thanks __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

06-04-2009, 10:13 PM	#9
corn Registered User Join Date: Dec 2003 Location: here Posts: 5,789	Re: 98' S-10 Air Conditioning problem? Pretty sure you just need a paper clip or jumper wire between the two connector wires.

06-05-2009, 06:35 AM	#10
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Re: 98' S-10 Air Conditioning problem? Thanks corn! So far it's been working fine but maybe the switch is going to go up this summer. No biggie, it should be easy enough to fix. __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

06-05-2009, 11:27 AM	#11
robin58 Registered User Join Date: May 2007 Location: Louisiana Posts: 763	Re: 98' S-10 Air Conditioning problem? Sometimes the clutches start to go on these compressors. Gently tap it and see if it kicks in.

06-11-2009, 06:39 AM	#12
68C15 blood type; Retumbo Join Date: Jan 2004 Location: next to my reloading bench Posts: 10,269	Re: 98' S-10 Air Conditioning problem? FYI, a system with a 10% charge will have correct pressures at rest. but once activated it will run down the low side fast and kick off. since the refrigerant carries the oil to the compressor a low charge will destroy the comp., fill the condensor with debris, coat the inside of lines and evaporator with "black death" reducing system efficiency, and plug the orifice tube screen. make sure the system is full with the correct charge by weight, NOT PRESSURE Last edited by 68C15; 06-11-2009 at 06:39 AM.

06-13-2009, 03:15 AM	#13
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: 98' S-10 Air Conditioning problem? When I posted about jumping it out Corn was correct the wire connection just make a loop in it with a jumper or paper clip. The pressure is a quick idea if something is wrong but the right amount of referangent is the best way to tell. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

07-17-2009, 07:08 AM	#14
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Re: 98' S-10 Air Conditioning problem? UPDATE- the AC has continued to work intermittantly for the last month even though it "mostly" works. Yesterday I noticed when I stomp on the gas pedal to downshift the transmission it will kick ON the compressor and then the AC works fine. I always thought the WOT sensor or TPS is supposed to shut OFF the compressor when you downshift. Basically it's acting the opposite of the way it's supposed to. So now I'm thinking a sensor on the the throttle body needs cleaning or replacing. Am I on the right track??? __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

07-17-2009, 07:17 PM	#15
68C15 blood type; Retumbo Join Date: Jan 2004 Location: next to my reloading bench Posts: 10,269	Re: 98' S-10 Air Conditioning problem? the ECM turns off the compressor during WOT by deactivating the clutch relay. if the TPS was acting backwards you would be asking about severe driveability issues instead. after re-reading your posts i am wondering if the ECM is recieving a constant request from the control panel (bad switch on dash). it sure wouldn't be the first time I seen a bad HVAC control panel on a late model GM. of course as luck would have it I am now home for the weekend and not at work. if someone (CORN) could remind me on Monday I can check to see which wire sends the AC request signal to the ECM. then I could post that and you can check for an intermittent open. hint-hint larry



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