Hi,new guy here with an AC question.I have a 1996 Yukon that I have had for 2 years and the AC has never worked as long as I have had it.The previous owner said he had it checked and the compressor is bad.I unplugged the harness that connects to the compressor and checked for power.There are 2 wires going into the connector,green and black.I checked both wires with a test light and dont have power on either one.Could this be my problem?
New guy with an AC question
- Thread starter 96SLE
- Start date
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SunlitComet
OBS Jedi-Do Good
Welcome again is this the connector up top on clutch unit or at the rear of compressor.
If up front lets start out by checking out your compressor relay in the under hood block. If you probe for power in the relay socket you should see bat voltage on two different terminals with ignition on. They are fed by "IGNE" and "A/C comp" fuse if that is fine reinstall relay and listen to see if it clicks with engine running when a helper turns on the a/c from inside. If not ensure the light green wire on back of hvac control head puts out battery voltage when a/c is selected and fan is on. Start with that. Also do you have any info on the refrigerant charge status ?
If up front lets start out by checking out your compressor relay in the under hood block. If you probe for power in the relay socket you should see bat voltage on two different terminals with ignition on. They are fed by "IGNE" and "A/C comp" fuse if that is fine reinstall relay and listen to see if it clicks with engine running when a helper turns on the a/c from inside. If not ensure the light green wire on back of hvac control head puts out battery voltage when a/c is selected and fan is on. Start with that. Also do you have any info on the refrigerant charge status ?
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Thanks for the reply.This is the connector on top right behind the pulley.I dont see another connector on the compressor.I pulled the relay and I do have voltage on two terminals with the ignition on.I dont have anybody here to help check the relay right now so I just swapped it with the starter relay since they are the same and still nothing.I dont have the dash apart so I cant check the control head but I do have voltage at the dryer so I guess that means I have voltage coming from the control head.I'm just wondering if the problem is in the wiring and not the compressor since I dont have voltage at the compressor.
As far as the refrigerant goes,I have no idea.
As far as the refrigerant goes,I have no idea.
SunlitComet
OBS Jedi-Do Good
The various pressure switches will have voltage present on one side and the engine computer reads them by which ones are on or off to see if it is safe to operate the compressor. As for the other connector on the compressor you should see a red colored connector or body out the back but reccessed in the unit. It shoul have two wires on it too. That it the high pressure "I am about to blow up" cut-off switch. should also see one on top of the compressor line block colored green or black and again on the drier/accumulator unit. With engine off can you turn the compressor by hand from the front? Also keep in mind if engine is not actually running the compressor is disabled. The computer has final say on weather or not compressor relay is activated. Any chance you can get a freon refill kit with a gauge? After all these years of not running I am sure it will need it. There is a possibility that after such a long time not operating the compressor may have or will develop other problems. Typically one of the first hings you check when non-operational is a low freon charge.
OK,I found the other connector on the back of the compressor.Dont know how I missed that,it was right there in front of me.I am getting voltage there so the only connector that's not getting voltage is the one on the front just behind the pulley.And I can turn the compressor by hand when the engine is off.
SunlitComet
OBS Jedi-Do Good
That is about right your computer may not be activating the clutch relay becuase the freon charge may be way to low. A gauge set or refill kit with gauge would really be good right now if you can get it.
SunlitComet
OBS Jedi-Do Good
No unless you have a jammed, damaged or worn out compressor it does not need to be replaced. If you are convinced you have a decent charge in it then something electrical is getting in way. When can you pull off your dash bezel to check hvac head unit. Does it a/c indicator bulb light when that and fan is turned on?
It will be the weekend before I can take the dash bezel off.When I turn the AC on the button does light up.I cant say for sure that I have a full charge but when I hook the guage up it is showing full.I am not an AC guy so this stuff is alien to me.I can change the parts out no problem,but I dont have any experience diagnosing the AC system.
This is totally unrelated but the funny thing is I bought this truck 2 years ago and I have not spoken with the previous owner since then because we live about 30 miles apart and we dont know each other except for the transaction with the Yukon.He emailed me this past Saturday night and asked if I would sell it back to him because it was his dad's before he got it and it has a lot of sentimental value to him.
This is totally unrelated but the funny thing is I bought this truck 2 years ago and I have not spoken with the previous owner since then because we live about 30 miles apart and we dont know each other except for the transaction with the Yukon.He emailed me this past Saturday night and asked if I would sell it back to him because it was his dad's before he got it and it has a lot of sentimental value to him.
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SunlitComet
OBS Jedi-Do Good
if the light comes on lets assume that the head unit is fully functional. Take the connector off of each of the pressure switches and jumper them with the a/c on and see if one activates the system. Do not let it run beyond 5 seconds at first and gradually increase each time to see if if the aluminum lines on the compressor get hot and cold separately. any mechanical noises that get out of hand shut it down, if one line gets burning hot in a few seconds shut it down, If it stalls your engine-well it will shut itself off if there is not change in temperature on the lines shut it down. Once you seem comfortable that it is cycling on and of about 8 times a minute see how the air inside feels. Report back with results.
