1973 valiant 318 car stalls when compressor comes on

Heating / Cooling / AC

  1. 1973 valiant

    1973 valiant 1973 valiant

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    I even ran a separate battery ran the compressor power wire to the battery and a ground from the battery compressor had the car running and compressor kicks on but car stumbled even with the idle up put it in gear car stalls something has to be wrong with the compressor or it's overcharged I'm going to have to suck it down but can't do that nobody has a r 12 recovery system anymore this car was never retro fitted
     
  2. 1973 valiant

    1973 valiant 1973 valiant

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    I tested the compressor as a stand alone system using a separate battery and running the car power to the coil and ground to the body of the compressor
     
  3. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    Tested how. Exactly. The way to test for clutch amperage is battery NEG---ground---compressor body----------(through clutch)---------out compressor wire-------to multimeter ON AMPS--------to battery POS. Compressor clutch should engage or click and meter should show amperage draw somewhere aroud 4A or less
     
  4. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    Then "cheat."

    First research what it should be running for temperatures and pressures and see if it will run long enough to see what you have. If it seems high, dump a small amount of refrigerant and see if the pressures/ temps come into line. Learn to measure suction (low) side superheat. This will help tell you if system is over-charged. You measure low side pressure and look at the gauge / chart to convert that pressure reading to R12 satureated temperature. You measure the temperature of the low side line while operating, with a probe and wrapped with insulation or rag at the probe. This then gives you TWO temperatures-------the one you measured and the converted temp/ pressure off your low side gauge. You subtract those two readings and that is superheat. You want AT LEAST 15F difference and typically more like 20F


    If you can find R12, and you can even find it around here........and I don't mean this aftermarket crap with LP (propane) mixed, I mean REAL R12 you can cheat. Vent what is there, and "rig" with fittings and your gauge manifold to hook up to intake manifold vacuum. Adjust the engine for highest vacuum, IE play with timing and idle speed. You will likely not get more than 20" Hg. Evacuate the system, Charge a small amount of liquid into the high side, to 'sweep' through the system, and re-evacuate only on the low side. Then recharge.

    Now if you are thinking that the compressor is bad regardless of charge, maybe bad bearings, scored cylinder/ piston, etc, you can also force it to run long enough to "feel out" how it's doing. Prepare to jumper power to the clutch as you did before, and dump the charge. Then jumper and run the compressor ? 10 seconds long enough to get a feel. If it seems rough and or drags the engine way down, I'd say the compressor is likely done for.

    THIS HOWEVER does not compute with a bad clutch. There is no reason that a bad compressor (bad internals) would cause a high electrical drain on the clutch. Either the clutch is drawing a lot of current because the clutch is bad, or the compressor is dragging down the engine because the compressor has problems, but the TWO should be separate issues.
     
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    • 1973 valiant

      1973 valiant 1973 valiant

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      Thank you that's great information I will go through the steps you wrote
       
    • 1973 valiant

      1973 valiant 1973 valiant

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    • 1973 valiant

      1973 valiant 1973 valiant

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      I finally figured out the problem with the air conditioning system I was able to get the valiant to the house the timing was off I had to advance the timing air conditioning is working but I still have to fine tune it but it's getting there thank you
       
    • RedFish

      RedFish Well-Known Member

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      OEM timing spec is probably about 10 btdc. About 14 btdc works better with todays fuel. You'll probably need to lower the curb idle a tad with the timing advanced.
       
    • 1973 valiant

      1973 valiant 1973 valiant

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    • 1973 valiant

      1973 valiant 1973 valiant

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      Thank you
       
    • 67Dart273

      67Dart273 FABO Gold Member FABO Gold Member

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      Post no2.............

      "It could be the idle is too low RPM, and or that the idle mixture is way wrong and causes the engine to sag, and check timing while doing so as well"
       
    • 1973 valiant

      1973 valiant 1973 valiant

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    • 1973 valiant

      1973 valiant 1973 valiant

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      Thank you , the timing marks are way off but it is the only way I can get her to run smooth way advanced can't see the marks way above I did shut her down pulled number 1plug got her on top dead center on zero pulled the cap off it's on number 1wire with rotor pointing to it looks like some freeplay when I turn the balancer back and forth has some play or the balancer slipped but I drove her and no pinging starts right up and not running hot and so much more power got her at 870 rpm s at idle a little high but when i.put her in gear the ac does not stumble and it's not banging in gear it has a egr valve but it's not connected maybe it's stuck I better check it out
       
    • 1973 valiant

      1973 valiant 1973 valiant

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    • 1973 valiant

      1973 valiant 1973 valiant

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      Found propane in the system how can I handle this situation safely maybe I can get a coupler and run it in my grill lol
       
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