02 saturn L200, no power to a/c compressor

Discussion in 'Domestics' started by heyarn, May 2, 2011.

  1. heyarn

    heyarn Full Member

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    4 cyl. auto saturn, fuses are all good, blower works fine, the little orange light comes on on the control panel, no power is getting to the compressor, or to the high presure switch, is there a bcm?, a wiring diagram could be helpful,, thanks for looking
     
  2. Gus

    Gus wrench

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    Has the vehicle been checked for codes? If an A/C pressure sensor code is set(may not turn CE light on), the compressor is disabled.....could be a sensor problem, or could be low on freon due to a leak.....
     
  3. billr

    billr wrench

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    Generally there is more than one limit-switch, maybe low-pressure and temperature as well as high-pressure. Jim F. would you please post a schematic?
     
  4. Jim Fairbanks

    Jim Fairbanks wrench

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    This is for manual AC...if it is auto let me know and I will post those....Jim

    [attachment deleted during maintenance]
     
  5. Jim Fairbanks

    Jim Fairbanks wrench

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    1 more....Jim

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  6. billr

    billr wrench

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    See why we say "Jim has everything"? Those schematics should give you a good chance at isolating the problem; but you will see it seems both the PCM and BCM are involved...
     
  7. Gus

    Gus wrench

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    If you look at the last two schematics, the PCM grounds the relay to power the compressor clutch......however, it won't do this unless it is reading the correct pressure reading from the pressure sensor.....so either the pressure sensor is bad, or it's sending a low pressure reading to the PCM because there is a leak, thus the compressor is disabled.....

    You either use a scan tool to check for codes and read the data from the pressure sensor, or attach gages and take a direct reading of the system(low and high side)....pressure on both sides should approximate ambient air temp(i.e., if the ambient air is 70F, the hi and lo sides, on a cold engine, should be about 70psi).....if the gages read ok, but the compressor doesn't run, then codes have to be read, and also the data from the sensor....

    In the old CCOT systems, you could jumper the connector to the pressure cycling switch to see if the compressor would engage....can't do that with a pressure sensor.....

    BCM probably passes info to the PCM, to disable the compressor, like data from the PS switch....like during a parking maneuver where the wheel is turned completely to left or right, putting a load on the engine....
     
  8. heyarn

    heyarn Full Member

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    thanks for the help, i'm getting the on sat to try and fix it again, i'll let you know how it turns out,
     
  9. NickD

    NickD wrench

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    First thing I check on these things is the hub/idler pulley gap for 20 mils, these hubs are pressed on and tend to press off. Then I hot wire the compressor clutch with a remote starter switch with gauges attached to check for proper operating pressures to make sure that is operating properly. Using the remote starter switch lets me quickly turn it off, don't want to run that compressor with low operating pressures, can damage it.

    If real low, like zero on both sides, check the entire system for oil leaks, add some R-134a, EPA doesn't mind if you waste a pound for this then get out the electronic leak detector. Have to find the leak and repair it. If static pressure is good, but runs low, very typical for an R-134a to lose about 10% per year, ten years adds up if the system was never topped off before. If all looks okay, then checking the condenser and evaporator for debris and proper fan operation, you cannot properly charge a system by pressures with any debris in these systems. Believe this vehicle uses the variable displacement V-5 compressor, and these are exceptionally difficult to charge by pressures, should recover and charge by weight. These also run full time, don't cycle like the older ones did, more like how the real old ones worked back in the 60's with the POA valve.

    Once the system is leakproof, and charged properly, and works great with the remote starter switch, rehook up the compressor connector, if it doesn't work then, that is when you dig into electrical problems.

    When my stepdaughters AC quit working last summer with recent hand surgery, had to tell her to roll down the window, she survived. But getting under her car this year, the reason for AC not working was obvious, compressor outlet hose was rotted out. No need to put gauges on that. Good to start off with a good visual inspection off the system. All depends on how your system died, can be a normal slow leak with noticeable poorer and poorer performance, or a stone chip on the condenser. Kind of like it worked great one day and failed the next.
     
  10. ktmbass

    ktmbass Newbie

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    2002 L200 Saturn 150K miles. . Just signed up to the forum. could not figure out how to post new so throught I would try a comment on the old post. Anyway. No power to the compressor. Read this model has only High pressure sensor and after looking I confirmed that. Plug has three wires, blue and black side by side and red on bottom. Can this be jumped to "trick the compressor to come on so I can charge the system? How?

    All fuses, relays, etc have been checked good. I do not know how to check the diode but from everything I have read it is most likely not the problem and the sensor has disabled the compressor because of low Freon.

    Help is appreciated
     
  11. kev2

    kev2 wrench

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    Rule of thumb the low side, and with engine off the high side (static) will need to be @40psi?

    post thre static pressure might help us help you,
     
  12. Mobile Dan

    Mobile Dan wrench

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    Generally, if the system pressure is so low that the compressor won't come on, adding 'freon' to the system will raise the pressure enough (to about 35 lbs) for the compressor to come on...at that point, the low side pressure drops down to empty your "freon" can.
     
  13. ktmbass

    ktmbass Newbie

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    Ok I get it. You guys ar razzing me about "freon". Whatever it's called doesn't the compressor have to be running to "pull" the coolant from the can. Hot as he'll here in memPhis. Help!
     
  14. kev2

    kev2 wrench

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    We are not having fun with you...don't worry.

    You did pull a vacuum on system?, now as you try to charge system the compressor will not engage, UNTILL there is about 35 or 40 psi.... less than that the system see it as LOW on refridgeant and inhibits the compressor.

    So without the comp running the two sides will equalize AKA static pressure... ...

    A tip sometimes putting the can in warm water will help send it into system....generally the the Evacuation (vacuum) empties the can easily....
     
  15. ktmbass

    ktmbass Newbie

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    2002 Saturn L200. No Power to A/c Compressor. Ok, just stopped by auto parts store to ask if #1 could you get a good pressure check without the compressor running, the answer was no. #2 will the system take coolant without the compressor running the answer was no. I do have a guage that shows red "trouble" when connected to low side. The guy at the auto parts store says that is because the compressor is not running. IS HE RIGHT?

    Again, I want to false start the compressor by jumping the harness on the high pressure sensor (which is the only pressure sensor on theis model) there are three wires red, black, blue. wich tow to jump to trick the compressor to come on for the purpose of charging. Is this a bad idea?

    105 here today. need to get to the bottom of this today.

    Ok spoke to a friend mechanic. he said no risk of frying anything by jumping the wires on the high pressure sensor. jumped every way possible only result was blue to black then the radiator fan came on and stayed on. Red to blue, radiator fan came on for just about a minute. Neither resulted in the compressor coming on.

    Just for kicks , decided to put my cheap guage that came with a can of coolant on the low side, same result, pressure goes straight to red "problem" on the guage, system will not take the coolant from the can.
     

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