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Thread: a/c compressor knock
07-03-2011, 07:57 AM #1
a/c compressor knock
i have a 1990 k-1500 4x4 with 5.7 engine. a/c compressor about 18 months old. i hear a slight knock in the compressor when running the a/c. last night it seemed to get a little louder.
is there a way to add oil to freon and have someone "top it off" with the freon/oil mixture, or can you only add oil before adding the freon ?
07-03-2011, 08:04 AM #2
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As far as i know the only way to add the oil is before you install it you put a measured amount of oil into the compressor. And if it is knocking then it is already starting to break apart.Mike
1997 Chevy S-10 Blazer 4X4 with 330K miles and counting (Hunting rig).
2009 Saturn Aura XE (wifes car)
2011 F-150 Crew 4X4
"Hold it to the floor till you see God.... Then Brake!!!!"
07-03-2011, 12:33 PM #3
thanks murdog..... yea, from what ive been searching, that sounds like it. i think i gotta replace the compressor.
07-12-2011, 09:52 AM #4
You can buy a can of pressurized oil down at Adv. Auto or something and add it in like you would freeon.
Did this on mine and I think it corrected my knock/noise.
07-15-2011, 09:04 PM #5
today i had a brand new compressor, accumulator, orifice screen, oil and freon installed in my 1990 k-1500 4x4 with 5.7 v-8.
its cooling fine, but i still notice somewhat of a slight nock when the compressor is turned on.....even increasing when i up the rpm's.....no where near as load as it was before he put the new compressor in..... is it normal for the compressor to make a slight knocking sound ? i dont have another vehicle to compare it to since i sold my 2003 s-10, but i dont think the s-10 ever made any knocking noise.... is the slight knock always present on these type of compressors in my 1990 ?
thanks for the help guys.
07-16-2011, 12:23 AM #6
I wouldn't worry too much if it's very slight. I've seen this more and more on aftermarket compressors. I put the one in my 94 suburban back in June of '08 and it's had a slight knock since day one, but it'll freeze you out of that truck still....
07-16-2011, 12:02 PM #7
thanks chris, i appreciate it....
08-04-2011, 06:10 PM #8
took the truck to the mechanic who fixed it 4 weeks ago. he said yes, the compressor is knocking more than it should be and will replace it free of charge.
BUT he is gonna chase down a Delphi compressor and install it. he said they are hard to come by, for some reason.
but it will be fixed soon....
08-05-2011, 11:31 PM #9
You need to have the entire system flushed, sounds like crap from the AC system keeps getting sucked into the compressor and causing it to knock, compressors in these trucks have no knock, my 94 was retrofitted to R-134a a while back, and the original compressor is very quiet, no knock, but the entire system was rebuilt.1994 Chevy Silverado 1500 Ext Cab 350 cuin TBI in dark Chevy blue
Original engine and tranny
wrecked twice stolen once
Diamond Plate bed rails
Original Alloy wheels
Original fancy smancy cup holder
Original plastic bed liner
K&N Cone Air Intake
Dual MagnaFlow exhaust(not true dual) with chrome tips
MSD Street Fire Performance Ignition coil
08-08-2011, 04:17 AM #10
thanks ethan.... supposedly he does flush and vacuum the entire system out.. at least that is what he says he is doing..... hope to get it repaired this friday with the Delphi compressor.... its got a 1 year warranty, so if it keeps failing he will continue to get it back.
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