2005 Yukon Denali - A/C low side valve size? Standard Shraeder?

Discussion in 'Engine & Drivetrain' started by David Cloes, Sep 13, 2018.

  1. David Cloes

    David Cloes TYF Newbie

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    Sep 13, 2018
    A/C wasn't blowing super cold, so I attached my refrigerant can with the cheapo gauge and it was in the green, so didn't add any R134a. when I removed the attachment from the service port (low side), I could feel that it was now leaking. It was very minor, but now I need to replace the valve.

    The system is charged, so I'm looking at using the Mastercool 81490 R134a Valve Core Remover Installer that allows you do this without evacuating the system.

    Youtube videos showing folks doing the replacement make it look like a snap on other cars, but if you read the reviews of the tool, tons of complaints - However, I think that it's from people that didn't know that there are different size valves and bought the $35 tool when they needed the $80 that does standard, JRA's, and R12. Specifically, some complain that they backed off the valve, but then it's too large to fit through the tool opening.

    My hope is someone knows with certainty that the Mastercool 81490 works on a 2005 Yukon Denali.

    If not, my backup plan is to buy the tool, go to the dealer and buy the valve for my vehicle and make sure it passes through the tube before actually trying it on the vehicle.

    Yes, I know it won't work on the high pressure side, but it's only the low side that's leaking.

    If you think that evacuating the system is the way to go because the system would benefit from fresh oil and refrigerant, I'm interested in opinions too.

    Here's a video of the tool being used.

  2. Tonyrodz

    Tonyrodz Full Access Member

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    Feb 16, 2012
    Central Jersey
    I don't have an answer for you, but that's a cool little tool.
  3. OneofFew

    OneofFew Full Access Member

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    Jun 25, 2018
    Talullah Falls, Ga
    I had the same issue and managed to seal the leak just by tightening the valve a little, don't over-tighten.
    I do believe it is a standard schraeder, but I did grab a kit from the AP store- part number [Factory Air- 26775] that comes with the high side valve and 3 schraeder valves. It's always a good idea to have one of those kits on hand whenever connecting a gauge set to your A/C as the valves often leak afterwards.
    Schrader valves can be changed with that tool you mentioned, the high side cannot and needs to be changed with the system empty.
    As to evacuating the system just to put in fresh oil and refrigerant-
    No. The refrigerant is not a wear item, the oil may get a little dirty although I have never seen nasty oil without a bad compressor. You will never be able to get all the oil out without completely rebuilding the system. Oil is retained in the compressor, the dryer/accumulator and evaporator and condenser. If it ain't broke, don't touch it.

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