A/C Question - Compressor won't start

[holly wood]

Hi all,

When i turn on the A/C in my 1980 Vette, the compressor cycles (clicks)on and off , about every 5 seconds, only staying on a second or two. I just recharged the system with R134A, and it still does this...

Any ideas??


Roger Holly

 

[wishuwerehere82]

Roger,

I am assuming that it still doesn't cool the car.

When it does that, it's either too much freon or too little.
How does it cool? If it gets real cold and then cycles, it is too much.
If it isn't getting cold and cycles, then it needs some more.

Also, the cycle time depends on the outside temp. and how high you have the blower. As the heat is transfrerred from the inside of the car to the condensor coil in front of the radiator, the compressor turns on and off to replace the freon charge in the evaporator. If it isn't cooling and cycles after a second or two, the freon charge is too low and the low pressure cutout switch turns the compressor off until the pressure comes back up again.
R134-A is a poor substitute for R12 and doesn't cool nearly as well but it is all that we regular people are allowed to use.

Good luck.

Pete.

Pete.

 

[holly wood]

Thanks Pete,

I will go add another can, and let you know what happens,
and yes, the cycling is so rapid there is no cool air whatsoever.

Roger

 

[brusso]

Try setting the controls to "max" and temp to most cold with the doors open. With this condition, the compressor should run pretty much constant. You may have a problem with the temp control cable/linkage. In other words, the A/C is'nt being "called" for. This is of course if you're sure that it has the propper amount of freon.

 

[holly wood]

Thanks for all of your help, i added another can, and it still cycles but MUCH less frequently, like every 30 seconds, give or take. The system was empty...does three cans of refridgerant sound right? So far I put in two.

Roger

 

[holly wood]

I just added another can of R134A, and all is well now.

Is it common to run low (or out) of freon after many years?
Does it leak out somehow, or just get assimilated into the works?

I hope I don't have a leak, if i do it is most likely very slow.

Roger

 

[wishuwerehere82]

Leaks are common at the fittings, at the compressor or at the compressor shaft. Most leak out over winter storage as the shaft seal shrinks with the low temperature. Go over your fittings to make sure they are tight. There are O-ring seals inside that can get flat spots on them.

There should be a sticker on your system somewhere that tells what the normal charge is for the system. 3 1/2 Lbs. sounds about right.

 

[Robin7TFour]

roger, call around to your local a/c repair places. i think the amount of 134a will be slightly different than r-12. 3 cans should be close. what is the temp reading comming from the center vent with the a/c set on high?

 

[holly wood]

I'll check with a digital thermometer, is feels colder than I ever remember it !!


Roger

 

[Robin7TFour]

from what i vaguely remember,if you have a 25 deg difference bbetween the vent and ambient temp that's a real good thing.