C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

ac not working

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Old Aug 8, 2009 | 08:39 PM
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hi, My 85L98 with manual ac is not working (blowing hot). the compressor will not come on. when guage is hooked to low side, guage points to green. so I am assuming charge is good. fuse is also good, but i cannot seem to locate the relay for the ac. also, all the stickers indicate R12, but all the fitting are 134 fittings???? what a pita this is turning out to be. any help would be appreciated.
Thanks
Mike
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Old Aug 8, 2009 | 09:04 PM
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There should be a low pressure/cycling switch in line to top side of evaporator housing under hood....if you jumper that connector will compressor engage ?
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Old Aug 8, 2009 | 09:10 PM
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Originally Posted by TWISTERUP
There should be a low pressure/cycling switch in line to top side of evaporator housing under hood....if you jumper that connector will compressor engage ?
I just jumpered the switch, and yes the compressor came on, your getting me on the right track now what?

Last edited by carolinamountains; Aug 8, 2009 at 09:19 PM.
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Old Aug 8, 2009 | 09:32 PM
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The system has likely been retrofitted from R-12 to R-134... also sounds like it's low on R-134 since the jumper caused the compressor to engage. The correct way at this point would be to evacuate and recharge the system. Whoever did the retrofit should have placed a sticker under hood w/the proper amount of r-134 to use. I'd guess 1.1 to 1.3 lbs BUT that's just a guess. You might try adding a can to the system (leave the switch jumpered while adding) but getting the proper amount in will be a guess. It would be good to have a set of AC gauges hooked up to the low and high side at this time. R-134 systems don't use near as much as the R-12s so disregard the R-12 stickers. It would also be a good idea to add AC oil to the system.
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Old Aug 8, 2009 | 10:01 PM
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thank you very much for the help, It makes sense. I will do what you said on Monday.
Thanks Mike
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Old Aug 8, 2009 | 11:51 PM
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I hate to spoil things but it's possible the previous owner didn't have any R-12 gauges and they're hard to find new so he may have converted the fittings so he could use R134 gauges but left R12 in the system. You never know.
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Old Aug 10, 2009 | 01:22 PM
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system was evacuated of freon and new 134a was added. still nothing when the switch is hooked back up. after tapping on the switch (low pressure cuttout) the compressor came on.
I figure now that the original problem was probably faulty switch with the system maybe a little low on freon. now its all working again and I know fer sure I got 134a. and I put the stickers in there that says 134a
Thanks for the help guys
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Old Aug 10, 2009 | 02:38 PM
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Originally Posted by carolinamountains
system was evacuated of freon and new 134a was added. still nothing when the switch is hooked back up. after tapping on the switch (low pressure cuttout) the compressor came on.
I figure now that the original problem was probably faulty switch with the system maybe a little low on freon. now its all working again and I know fer sure I got 134a. and I put the stickers in there that says 134a
Thanks for the help guys
The switch was bad in my 91 and started a bunch of problems.. 15 bucks and 5 minutes to change and at least on a 91 you do not lose the charge or anything.. Mine would work sometimes when I checked with an ohm meter there was 15 ohms across it so could not get enough current to pull the clutch in..
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