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  #1  
Old 06-16-2003, 03:27 PM
mhl0125 mhl0125 is offline
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Location: Medford, NJ
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Angry Pulling hair out over my a/c..HELP!!!

Car has been in shop for one week now. We replaced the compressor and the reciver drier. No cold air. Replaced the sunload sensor..no cold air. Tested all of the relays, fuses, and trinary switch...all test OK. Pressure on both the low and high sides within range. My mechanic is suggesting the ECU. This is a big expense and I don't want to trial and error this one. Half of my air is gone and I want to save the other half. It seems when the fans turn on, the compressor comes on and when the fans shut off the compressor shuts off. Even when the climate control is set at 65 and it is in the 80's out...I can't get the fans and compressor to stay on for any length of time. I am going nuts. Please, please help me! Thank you all. I love this site.
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Michael
1994 Barcelona Red SVX-LSI
Two-owner:169K
1995 Emerald Green SVX L AWD
#80 - Custom intake w/cone filter
99K with killer stereo system
2002 Acura MDX-Touring Edition w/navigation
2008 Toyota Prius
1987 Mercedes Benz 560SL
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Old 06-16-2003, 03:38 PM
lee lee is offline
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Micheal, I think you need to do some electrical tests with a VOM. Do you have the pinouts/voltage values between the climate control unit and the ECU? Check the voltage at the ECU and see if the climate control unit is sending the correct state. If that's OK, then check the line from the ECU to the A/C compressor relay and see what it's doing.

Have you run the system diagnostics? Do you have any flow charts for problems?

My ECU was bad (for controlling the A/C anyway) and I bypassed it with a home-made circuit. I will post that if you want, but I think you have a different problem than I had as my ECU would NEVER turn on the compressor.
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Old 06-16-2003, 04:10 PM
mhl0125 mhl0125 is offline
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Lee,
Thanks. My mechanic has done a slew of electrical tests with a VOM. We have the electrical flow chart of the system and we ran the climate control diagnostics. What other system diagnostics need to be run? He thinks it's the voltage between the ECu and the Climate Control. I don't know if your fix will help, but I would love to show it to him. I'm grasping at straws now. Please post your bypass fix,
If anyone knows any specific tests to do, please let me know. Thanks again.
__________________
Michael
1994 Barcelona Red SVX-LSI
Two-owner:169K
1995 Emerald Green SVX L AWD
#80 - Custom intake w/cone filter
99K with killer stereo system
2002 Acura MDX-Touring Edition w/navigation
2008 Toyota Prius
1987 Mercedes Benz 560SL
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  #4  
Old 06-16-2003, 05:07 PM
lee lee is offline
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Location: Indialantic, Florida
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OK, here's what I did. But this was based on the fact that the climate system was sending the correct signal to the ECU, while the ECU was not behaving correctly. Also note, my solution does not provide for cutting out the A/C under full throttle like the ECU is supposed to do ( but I never drive that way anyway). In electronic terms what I'm showing you is a voltage follower circuit. I use the climate control signal to control a relay, which in turn controls the OEM A/C relay. I did it this way because I didn't want to subject the climate control unit to what would happen if I asked it to directly control the A/C relay. Where it says "T" that means I spliced into the circuit. Where it says the wire from the ECU to the relay, I cut that wire and went from my circuit off to the relay so the ECU output goes nowhere.
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