A/C Issues

Discussion in 'The Garage' started by 95PGTTech, Jun 20, 2007.

  1. 95PGTTech

    95PGTTech Well-Known Member

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    When I worked at Haldeman Ford, I got all the diesel and electrical work. I was happy to shovel the bullshit A/C work to the certified tech. :gtfo: Unfortunately, it's my wife's car, so I can't get out of this one.

    When we first test drove the car at the dealership, the A/C blew warm. Like 75 degrees warm. He said it "just needed a charge." I rolled my eyes at the standard excuse, knowing full well there was probably a gaping hole in the bottom of the compressor or something. When we went to pick it up for delivery a week later, he said he had it charged and it was ice cold. That lasted less than two days.

    Assuming small leak, I stopped by my work and picked up the generic R134a refillers and thought about the stop leak one. Thankfully, I didn't buy that one. I put the gauge on and it was in the super high "danger" zone. Remembering that an overcharged system functions just as poorly as an undercharged one, I responsibly evacuated the system with an environmentally-safe A/C machine. ;) I recharged the system to the blue "filled" portion of the gauge with the A/C system on Max Cool just like the bottle said. I filled it to the middle of the blue zone. The compressor clutch was not engaging, and I went into the cabin and it was still red hot. After a few minutes, the gauge was reading the top of the blue zone, then higher, and finally back in the red.

    So I stopped being a vagina and I got my first real professional set of gauges. The compressor clutch still does not turn on. My readings are 46 psi low side, 48psi high side with the A/C in the off position and 46 psi low side, 49 psi high side in the A/C Max Cool position with the blendoor turned to full cold.

    I ran the OASIS on my VIN for
    1) Climate Control (208000)
    2) Lack of Cooling AC (208200)
    3) Other Climate Control Concerns (208999)

    It turned up no applicable TSBs or SSMs.


    On to the online service manual...A/C symptom chart...Insufficient A/C cooling...go to refrigerant system tests.
    It is about 85 degrees outside and high humidity, so picking the right chart, my pressures should be...25-45 low side, 140-250 high side
    clutch cycle times should be 60-infinite seconds on, 3-12 seconds off

    taking that information to the charts...normal low pressure, low high pressure, no cycle
    none of the categories fit those conditions, all the normal low/low high have fast or erratic for cycling

    so I am stuck with:
    Erratic Operation or A/C Compressor Not Running
    possible problems:

    A/C Cycling Switchâ€â€Dirty Contacts or Sticking Open
    Poor Connection at A/C Clutch Connector or A/C Cycling Switch Connector
    A/C Electrical Circuit Erratic



    There is no pinpoint test linked, and I cannot find one for the A/C cycling switch. :help2:
     
  2. 95PGTTech

    95PGTTech Well-Known Member

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    I have good power when A/C Max Cool is selected at the cycling switch on the Purple wire, but not ground going out on the Blue/Yellow wire. I have continuity between the Blue/Yellow wire at the cycling switch and the Blue/Yellow at the High cutout switch.

    When I refill the refrigerant to its intended capacity and I jumper the cycling switch, the compressor clutch engages and stays engaged. My readings go to 35/250 right where they should be and stay there, and the system blows fairly cold. I don't have a temperature gauge on me, but the chart says 35-45 degrees out the center vents at this temperature, I'm sure it will come up a bit when I'm not just idling the car and I'm moving some air across the condensor.

    What worries me is that although it would make sense to replace the cycling switch, when i plug it back in (not bypassed), the compressor will still kick on every so often for a split second now. this could be an intermittent failure, or it could mean the cycling switch is not the problem at all. the job of the cycling switch is to prevent damage in case the system has too high or to low of a pressure, and if I'm bypassing it, I could be causing more harm than diagnosing anything at all.


    I also thought the system was supposed to change pressure levels...I thought the compressor was supposed to kick on around 40 psi and as stuff gets colder on the low side and pressure drops, it is supposed to turn off around 25 psi to prevent freezing. is it just so damn hot outside that this is not happening and my pressures are staying the same, even as the compressor runs?

    this is why I hate air conditioning bs... :nonono: