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Low Side High High Side Low

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  • Low Side High High Side Low

    Hi all, new member here. I have a 2008 Outback 2.5 basic with 57,000 miles. The previous owner was a little old lady who seldom drove so it sat in the carport all the time. The compressor kicks on/off every few seconds and the vent temps are in the low 60's (outside temp 85). The condenser was clean so I tried adding a little R134a but that didn't help, so I bled some out (yes, I know, but it was only a little) and the compressor stopped cycling and stayed on, but the temps stayed the same. I figured the cheapest and easiest repair was the expansion valve so I bought a Denso valve, desiccant bag, and a set of gauges and had my mechanic recover the refrigerant. I replaced the parts and all o-rings, vacuumed down to -30, let it sit overnight to verify no leaks, then let the pump run for two hours (it's a two-stage pump). I then added 411 grams of R134a (sticker under hood says between 369 and 425g). The low side maxed out, the high side was 155 and the quick cycles resumed. The specs say the range should be around 25 psi to 220 psi. I'm thinking a weak compressor but wanted to hear other opinions.

    Thanks in advance.

  • #2
    Doubt it, the compressor is cycling, and the high side is above what static pressure would be for the temp. What do you mean by "low side maxed out'? Give a pressure reading and what happens to both the high and low side pressure when the compressor cycles. Time to stop throwing parts at it and diagnose. We may end up trying some part like a pressure transducer, but that will have to wait until we know more. Are condenser fans coming on?