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Compressor cycling on / off during system fill process

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  • Compressor cycling on / off during system fill process

    I have a 2000 Dodge Dakota that I am trying to get the A/C working on. I had to change the orifice tube and the dryer, so I had it evac.ed and did the work. I then pumped it down and it held good vacuum, no leaks. I then started to fill it with R134a and got some interesting pressures on my gauge set. It needs 2.6 pounds for a full charge. I put in the first pound. The compressor started to cycle on and off in about 5 to 10 sec intervals. With compressor on, low side goes to 50 to 55 psi, but has gotten as high as 70 psi on several cycles. The whole time, compressor is on or off, high side stays at about 85 psi. Ambient temp was 93F. With the AC off, low is at 100psi and high is at 90psi. My question is, seeing these pressures, and the compressor cycling with 1 pound of R1134a in, should I keep going with more refrigerant OR does what I am seeing indicate a problem in the system. Thanks!

  • #2
    ? If source of new 134a is warm it should take about 1/2 charge with engine off. Weigh it in and fast can almost disregard pressures till closing in on fully charged and stabilized.
    Right now/then you are just seeing slow response for pressures with compressor cycling on and off get it full and not too much see what you have then. Cool condenser with water and raise idle helps.

    Other way is pay to force in exact proper charge without engine running at all avoid this part of the hassle,

    MetroWest, Boston