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7/16/18 5:24pm - Original Message: 'A/C cycling time'
Drose Lifetime Member
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Solon, OH - USA


Joined: 10/14/2015
Posts: 19
Having a problem with my A/C.
It blows cold air but the on and off compressor cycle time is like 10 seconds. What is a normal on off cycle time for the A/C on a 81 vette.  Outside temp for the day is 85 degrees.  The mechanic says the gauges are reading properly.  I figure I am in the process of crashing a compressor.  The system has been updated to use 134A.  Any help appreciated!!
Thanks, Dan

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7/16/18 5:52pm - Reply: 'Re: A/C cycling time'
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Overland Park, KS - USA

1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.

Joined: 7/9/2003
Posts: 521
Does the '81 have a temperature setting capability like most vehicles today do? If not, I'm not sure why it would be cycling unless there's something wrong with the pressure settings but you said those checked okay. As you're probably aware the C3 Corvette A/C system was marginal at best with R12 refrigerant. Unless the conversion process changed out the evaporator and condenser, then the efficiency would be even less. That's because R134a is a less efficient refrigerant and has to have a larger condenser and also uses a different oil. Hopefully they removed the old oil from your R12 system and added the new oil.

|UPDATED|7/16/2018 3:52:53 PM (AZT)|/UPDATED|


1973 L-82 4 spd

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7/16/18 6:55pm - Reply: 'Re: A/C cycling time'
manchestershark Lifetime Member
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Equinunk, PA - USA

1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.

Joined: 10/31/2007
Posts: 1975
I have a 72' that has been converted to 134. when pressure is up to requirement, it will cycle till it needs to work to cool the system. Mine blows about 48-50 at the duct on the dash. Best it's gonna get. As was said in previous reply, the system is antiquated and system cannot handle a COLD return. From 91 degrees outside and car in the sun, it took me about 12 miles at 45 MPH to get comfortable. Start your cooling process before it gets real hot, and it will be sufficient to be better than external heat. YES,I know, when you start from a hot car to begin the trip, it's going to take some time to bring the temp down.


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 Forums -> C3 Cooling and Heating Systems
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