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Thread: getting my AC working - a brain dump

  1. #1
    Join Date
    Jun 2017
    Location
    Oxford, PA
    Posts
    459

    getting my AC working - a brain dump

    Hello
    FOR QUALIFIED REPAIRMEN ONLY, OR IF YOU KNOW WHAT YOU ARE DOING…HIGH PRESSURES AND MOVING PARTS INVOLVED. THIS POST IS FOR INFORMATION ONLY…. Otherwise pay a AC technician the $300 bucks.

    My AC was not working in the MM. No surprise: the car has been off the road since Nov 2016 and got wrecked. 135 K on the clock.

    Here’s a path back to AC land….

    Here's the equipment:
    R134a gauges and vacuum -pump
    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    here's a sniffer to find out what is leaking
    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    R134a can be obtained at W-mart. Need three cans
    https://www.walmart.com/ip/SuperTech...SABEgKGEfD_BwE

    Physical check of system to see if anything is missing/hoses OK, etc… . Check = OK
    ----unlike all the cute TV commercials, no : unless you only need a smidge of R134a, you cannot just add a cheapo can with a gauge on it to the low pressure side –reason: there will be too much water vapor in there, the water will freeze and block the expansion valve and the compressor will just try to pump against a solid chunk of ice in the tubes. No good. So, you need to evacuate the system first with a vacuum pump. Pull it down to -30 in vacuum… Then see if it holds a vacuum with the pump off. That means you don’t have a massive leak.

    Print these instructions to see how to work your gauge set… keep them near the car: Take your time to digest these steps and work slowly. Never charge to the high side (red side) make sure your valves are closed off or opened as they need. During charging the high side stays CLOSED, read off the gauge set (see instructions)
    http://manuals.harborfreight.com/man...999/Q92649.pdf



    (EPA note: if there’s R134a in there, rule is to get it recovered by a certified garage HVAC service tech. Or measure your system using your gauges, only to find out all your R134a leaked out long, long ago and the system has zero left in it, maybe also thanks to a big front end smash up….)

    MM’s have a metal can in the lines near the battery called an accumulator, these collect water and corrode, made worse by some cheapo foam covering it, holding salt water against the unit.

    Add a can to the system, enough for the compressor to kick on, hopefully no squealing/seizing of the compressor.
    Use sniffer to check for leaks. Check inside the car at the AC vent – a leak will cause the sniffer to beep really fast, my car was not tripping the sniffer from inside . whew…or that means have to add sealer or replace the evaporator under the dash. Check along the hoses and around the compressor, no leaks…
    Check the accumulator bottom, OK, but under the foam...beeping, so the accumulator needs to be swapped out. Slow leak there. Accumulator is $20 bucks shipped at Rock Auto.

    https://www.rockauto.com/en/moreinfo...387829&jsn=406

    Watch this guy replace his Ford panther accumulator….he says the whole system takes 7 oz of PAG (oil) but he only fills the accumulator itself to 3.5 oz. good. Too much oil = blown seals, not enough = messed up compressor.

    https://www.youtube.com/watch?v=2bre6VBBhHM
    Look at MM manual to see what the low/high side are supposed to read for your local temperature the day you do this….low side 25 -35 psi on the blue gauge. 175-200 on the high red gauge. It’ll take a couple of cans up to three cans. Some people flip the can upside down to slug liquid R134a in there, that can damage the compressor, better to stick the can upright in a warm saucepan of water –it’ll take several minutes to empty the can which will get real cold as it drains.

    Measure the vent temps inside the car…fan on low shooting for 40F ish, higher fan speeds will read warmer, say 50 F.

    Keep checking the vent over the next few days to see how the system is holding up.
    Last edited by Agent2006; 06-14-2019 at 07:43 AM.

  2. #2
    Join Date
    Nov 2002
    Location
    St. John, IN
    Age
    45
    Posts
    14,251
    You never need to add oil unless you swap out the compressor, FYI.

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