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Wiring help: Can someone go multimeter their AC compressor wires! Please!

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acidikjuice

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Last year my AC compressor was working great, but the system had a small leak at the firewall. I just fixed all the leaks and recharged the system. Holds pressure/vacuum great.

However, the compressor will not start now. The compressor's clutch is not engaging! I have checked the fuses, the relays in the fuse box. Can't seem to track down whats going on here. It worked last year and I have about 60 PSI of 134a in the system, so the low pressure switch should be fine.

The compressor has three wires in a small harness going to it. Could some one please meter the wires and tell me their states/voltage with the compressor not engaged (but AC on) and the compressor engaged (obviously, AC is on :p )

I get 12 volts on each wire.

The black/white wire is connected to the ECU and the switch inside the cabin. The white/green wire is connected to the dryer (assuming that is the pressure switch) and the green/red wire I have no clue.

Any one have AC wisdom here? Or can send me some of the AC pages from the service manual ?

Thanks,
Will
 
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#2 ·
I have the same issue! I have charged my system and checked all the fuses, when I turn the AC on, there is no noise from the AC compressor, and nothing changes which makes me believe there is something that is not connected in the wiring system.
 
#3 ·
acidikjuice said:
Last year my AC compressor was working great, but the system had a small leak at the firewall. I just fixed all the leaks and recharged the system. Holds pressure/vacuum great.

However, the compressor will not start now. The compressor's clutch is not engaging! I have checked the fuses, the relays in the fuse box. Can't seem to track down whats going on here. It worked last year and I have about 60 PSI of 134a in the system, so the low pressure switch should be fine.

The compressor has three wires in a small harness going to it. Could some one please meter the wires and tell me their states/voltage with the compressor not engaged (but AC on) and the compressor engaged (obviously, AC is on :p )

I get 12 volts on each wire.

The black/white wire is connected to the ECU and the switch inside the cabin. The white/green wire is connected to the dryer (assuming that is the pressure switch) and the green/red wire I have no clue.

Any one have AC wisdom here? Or can send me some of the AC pages from the service manual ?

Thanks,
Will
Click to expand...
Did you ever find the answer? My FAL fans electronics seem to have caused your same exact problem. I smelled a little electrical burning smell come from the center vents when it failed. I don't know where the failure is. I took the A/C switch apart and looked to see if maybe it failed in there.. but it looked perfect. Any ideas?
 
#4 ·
acidikjuice said:
Last year my AC compressor was working great, but the system had a small leak at the firewall. I just fixed all the leaks and recharged the system. Holds pressure/vacuum great.

However, the compressor will not start now. The compressor's clutch is not engaging! I have checked the fuses, the relays in the fuse box. Can't seem to track down whats going on here. It worked last year and I have about 60 PSI of 134a in the system, so the low pressure switch should be fine.

The compressor has three wires in a small harness going to it. Could some one please meter the wires and tell me their states/voltage with the compressor not engaged (but AC on) and the compressor engaged (obviously, AC is on :p )

I get 12 volts on each wire.

The black/white wire is connected to the ECU and the switch inside the cabin. The white/green wire is connected to the dryer (assuming that is the pressure switch) and the green/red wire I have no clue.

Any one have AC wisdom here? Or can send me some of the AC pages from the service manual ?

Thanks,
Will
Click to expand...
This is what happened.

I turned on my A/C.
All of a sudden I heard a crazy clicking sound coming from the front of my car.
I smelled a little electrical burning coming from the center vents... very slight.
I knew it was some relay going nuts.
Turns out it was the relay inside of the FAL fan electronics.
The electronics' ground was bad. I fixed it and everything was fine... Or so I thought.
The A/C compressor never comes on any more.
The switch's lights work (orange, then green)... but no click sound for my compressor.
I checked the wire today at the compressor. When I turn the blower fan on and try the a/c switch I see NO voltage at the compressor wire.

Since all of this came from a bad ground for the FAL electronics, I replaced the electronics with FAL's latest version which seems to be all solid state. Very nice... I got everything back together and still... when I press the A/C button, my fans do not come on and I don't here a click from my A/C. I have connected the FAL A/C Green wire to the Green / Pinkish stripe wire that goes into the fuse box that is right next to the air filter. This wire works great for controlling the fans when you turn the A/C on. I am just worried that the original FAL electronics tried to sink a lot of current through that wire when the ground was bad which may have caused the burning smell.

I can't find a schematic anywhere that shows what happens between the compressor / front fan / the a/c switch anything!

Can anybody help? Thank you so much!

Jameel
 
#6 ·
I would take a battery and use a couple jumper wires and and try different combinations of those 3 wires and see if you can get the compressor to engage. Though I doubt it will, if you have 12 volts on all 3 wires you have a short somewhere. One of those HAS to be the ground and would read close to 0v.
 
#7 ·
I just checked the fuses and relays. They all seem to be good.

I put a volt meter on that Green / Pink stripe wire and I used to get 12V when I turned the A/C on... Now I only get 1.28V Clearly something has happened to that Green / Pink stripe circuit. Does anybody have any schematics that show where that wire goes. What electronics that wire deals with?

Any help would be greatly appreciated. Thanks!
 
#8 ·
I can't take it anymore guys... I have been living in Florida with this intense heat and NO AC!!! Does anybody have a wiring diagram for the AC system? More specifically, does anybody know anything about the Green / Pink stripe wire? I know, when I turned on my AC this Green / Pink wire would go to 12V when the AC worked correctly. I have check all of the fuses and relays that I can see and they seem to be okay. I have a 1995 Mitsubishi GSX.

Thanks a lot guys!
 
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