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Can a low R134a charge result in inadequate cooling even though the compressor is running constantly?

robocam on Sun August 09, 2009 4:05 PM User is offline

Year: 1985
Make: Chevrolet
Model: G20 Van
Refrigerant Type: R134a

I have a question about charging. Can one experience inadequate cooling due to a low charge even though the compressor is running constantly (assuming everything else is ok)?

Because what I'm wondering is if there is some "sweet spot" for the amount of refrigerant in the system that provides optimum cooling. Could both too little AND too much cause the system to blow warmer even though the compressor is constantly running? I'm asking assuming that everything in the system is in working order and that other things are not causing the decreased cooling capacity.

I understand that too low of a charge will cause the compressor to shut off (resulting in warmer air) and that too much somehow hurts performance, but I was wondering if there was a point where you could go too low, but not low enough that the compressor cycles, that causes the system to blow air that isn't as cold as it could be.

This is in a system with a fixed orifice tube.

chris142 on Sun August 09, 2009 5:47 PM User is offline

With the old R12 you just had to have the charge close and it would work well.

With R134a the charge needs to be very close to perfect. Depending on the size of the system of course. Having 4oz too much in a car that only holds 1.25 lbs would result in a problem.

Having 4oz too much in a Suburban that holds 4.25 lbs probly wouldn't matter.

So the answer to your question is yes a system can be low enough to not cool but not low enough to make the low pressure switch turn the compressor off.

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