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Thread: A/C Vacuum Question

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    Registered User Dr. JL's Avatar
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    A/C Vacuum Question

    I've replaced the heater/evaporator and am now in the process of recharging the a/c system. After 1 hour of the vacuum pump running the gauge showes 18 inches of vacuum. Is that a sufficient vacuum before I recharge with freon?

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    Hmm. The '95 manual (section 22) says to evacuate to 27 in Hg or better. Anything less, per the manual, indicates a leak.

    I've only evacuated and recharged an a/c system a couple of times, and never on my NSX. But water molecules and air are the big enemies of efficiency in an a/c system. Some shops like to leave the vacuum on a minimum amount of time because time is money. Someone in the business once told me to leave the vacuum on for up to 3 hours to really boil off all the water molecules. So, I did that and things worked well. But, I of course didn't repeat the process and leave the vacuum on for only an hour and compare results.

    Let's see what someone with more a/c experience has to say.
    Frank
    '96 NSX-T, red/tan
    '01 SLK 320
    '84 Z51 'Vette

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    Charter Gold ralph cerbone's Avatar
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    sounds like you have a leak , the number you want to see is 26 "(this is when the moisture starts to boil ) then should pull down more , after i hour shut off ,let sit,should hold. Check connections at pump also make sure pump has oil in it . hopefully your pump is leaking .
    Last edited by ralph cerbone; 06-23-2014 at 17:02.

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    Registered User Dr. JL's Avatar
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    Thanks all. I'm hoping the pump and manifold I rented from AutoZone is bad. The AC worked great before I swapped out the H-E due to a heater core leak.

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    Registered User Dr. JL's Avatar
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    Turns out it was a faulty gauge/manifold. Another set from AutoZone worked as advertised. Thanks for the inputs.

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    Registered User Dr. JL's Avatar
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    Turned out that I had a bad compressor, too. I ordered a new Denso compressor for half the cost of Acura parts dot com prices from AutohausAZ.com. New H-E, compressor and freon. Smells like a new car when the a/c is running!

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