1994 Honda Civic EX A/C compressor cycles on and off

Discussion in 'Civic' started by Mario Perez via CarKB.com, Apr 18, 2005.

  1. I recently purchased a 1994 honda civic ex with manual trans. and 112,000
    miles. The car is absolutely in mint condition inside and out. My problem
    is I would notice a slight hesitation occasionally in the motor while I was
    driving. When I lifted the hood to inspect I noticed it was the a/c
    compressor cycling on and off. My father in law checked the pressure and it
    measured as if it was at the appropriate range. He mentioned if the
    refrigerant is low the sensor disactivates the compressor. He added r134a
    refrigerant and pressure seemed to remain the same after going through
    almost the full bottle. After accelerating the engine to about 2500 rpm the
    compressor purged a blast of refrigerant through the relief valve. We
    checked the pressure and it was still in the same place(on the low pressure
    side). It still is cycling on and off. Could it be that it is overfilled
    and the compressor in cycling not because it is low on gas but because it
    is overheating or something? I noticed the problem alleviated a bit when
    the compressure purges the refrigerant. It also seems to not be cooling as
    it should. Any help would be greatly appreciated.
     
    Mario Perez via CarKB.com, Apr 18, 2005
    #1
  2. Mario Perez via CarKB.com

    motsco_ _ Guest

    -------------------------------

    Don't all honda AC units turn on and off automatically to prevent icing
    ? I know that household ones do. :)

    'Curly'
     
    motsco_ _, Apr 18, 2005
    #2
  3. Mario Perez via CarKB.com

    Randolph Guest

    Some cars have variable-ratio compressors (and a thermo couple at
    evaporator) and regulate cooling that way, but most have a thermoswitch
    at the evaporator that controls the compressor clutch. The '94 Civic has
    the evaporator thermo switch, and it is perfectly normal for the A/C
    compressor to cycle on and off. The cooler the weather, the shorter it
    stays on before cycling off again. If you are driving a 6 liter V8, you
    won't notice the cycling, but in a 1.6 liter I4 you certainly will!

    The A/C in my '94 Civic is no arctic blast, but it is more than adequate
    for Northern California summers. My Civic (R-134a) takes longer to cool
    down after sitting in the sun than my friend's late 80's VW (R-12) but
    the Civic has no problems maintaining a comfortable temperature even on
    100° days.
     
    Randolph, Apr 18, 2005
    #3
  4. As others have noted, some cycling is normal. It should follow the fan
    setting: at low fan speeds it should be on a couple seconds and off most of
    a minute; at high fan settings it should be on for several seconds and shut
    off for several seconds, fewer in warmer weather with the windows open.

    This would be a good time to have the A/C professionally serviced. You can
    be sure it is overcharged now, after adding a can blindly and seeing it
    vent. Although pressure readings will tell you if you are drastically low,
    the experts say that there is no reliable way to set the level of R134a
    except by evacuating and adding the proper amount by weight. I don't know
    why this should be, but I see none of the R134a systems have sight glasses
    either. Oh, well - that was a fairly crude way of filling R12 systems
    anyway.

    Mike
     
    Michael Pardee, Apr 18, 2005
    #4
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