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  • a/c diagnosis?

    my a/c doesnt blow cold at all. how can i diagnose what the problem is??? its a 97 and it only has 34000 miles on it
    thanks alot
    -ken-
    ~~~The Twisted One~~~

    My 30th is gone but soon a new era will begin.

  • #2
    1. Does the A/C compressor clutch engage?
    2. If 1 is yes, Does the A/C cycle? (on for 5 seconds (rough #) off for 5 seconds)
    3. If 1 and 2 are yes, What is the high side pressure. You can get this with a gage on the system or a scanner in the OBD port. At about 190 psi, the compressor should kick in. About 420, the compressor should kick off. If the compressor kicks in at 190 and it shoots to 420 in about 2 seconds, it is over charged (I doubt it if it was working and just stopped but it is very easy to over charge R134 systems).

    If the compressor doesn't kick in, it's probably either a bad clutch or low on freon (probably the later). If is low on freon. the low pressure switch will not send voltage to the A/C compressor to make it engage so checking the voltage to it doesn't mean anything right yet. I would get a couple of wires and run them from the battery to the compressor and see if it will engage. You can do this with the car off. You'll hear it click/clunk. If that works, it's probably just low on freon (which means it leaked out somewhere). You could shoot some freon in it and see if it comes alive again. Note, if you short the low pressure switch, but if it is out of freon (and the oil in mixed with the freon) you could damage the compressor (that is why the low pressure switch is there). Another note, if there isn't enough freon in they system and the low pressure switch is not letting the compressor kick in, the fans won't come on (for the A/C) either. I guess you could say if you turn on the AC and the fans come on but the compressor doesn't kick in, it is probably the clutch. My scanner will show on it when the A/C compressor is called for and should be on.

    If of that works, it's probably going to have to have the system opened up which will require a vacuum compressor to close so it might be time to seek professional help.

    If you don't have a scanner, now would be a good time. They are useful for more than engine codes. I have an Auto X-ray.
    2002 Electron Blue Vette, 1SC, FE3/Z51, G92 3.15 gears, 308.9 RWHP 321.7 RWTQ (before any mods), SLP headers, Z06 exhaust, MSD Ignition Wires, AC Delco Iridium Spark Plugs, 160 t-stat, lots of ECM tuning

    1995 Z28, many mods, SOLD

    A proud member of the "F-Body Dirty Dozen"

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