A/C pressure readings

[wrapperman]

Can anybody tell me what the pressure readings should be on the Ford F53 chassis air conditioner. My low side is 16 psi and the high side is 240 psi. Ambient temp was 97 degrees. I am getting a little freezing water around the evaporator coil right at the low pressure valve.
Is this normal or maybe a restricted orifice.
I cools just okay.
I don't want to take it in and be charged for servicing a good system.

[Iwannacamp]

I am no expert.. The normal r-134a suction pressure w/12-1500 RPMs with a cool cab would be about 35psig... The discharge sounds good. If it is 97 outside that's good...makes me think there may be a partial restriction in the liquid line somewhere.

Kill it and let it equalize fully. Have someone start it and watch the gauges. The high side may fall slightly before it begins to rise. It should stabilize and not really fall after it peaks. If it falls from say 275 to 230 or 240 or lower...i would look for a restriction. Probably in the orifice assuming it has one.

If it is low of charge...it is possible..then watch the head cause it's prolly gonna be high. That's a new subject.


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[Coach 350]

Agree with your pressure diagnosis. Head pressure should be 2x the ambient temperature + 20% is a good rule of thumb. Low side should be around 35 PSIG. Was it worked on before? Could have not been properly placed in a good vacuum and dirt could cause a restriction.


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[wrapperman]

Neither am I an expert. But I do have gauges and the knowledge of the Internet and friends on this forum.
I have added a little freon but the low pressure side never went up. Also the sight glass is solid liquid, both of those signs said do not add any more freon. I did not add anymore than 5-6 oz's.
It never was very cold to begin with and I should have take it I when I first bought it but because others said the dash air does not cool very well, I just assumed. Now I am wanting to do something about it. It does okay but the low pressure side shows something is amiss and I don't want to hurt the system or wait till it goes out.
Is it hard to clean the orifice? I don't mind buying a vacuum pump and trying myself but it could be a costly mistake.
What do others say. Please keep in mind I am not made of gold so I would like to try myself. (though my DW says I'm cheap).
Thanks for y'all's replies.

[Coach 350]

I was in the HVAC business for 20 years. The seals in your compressor could be leaking. Ford had a problem with their compressors. Can you rent a vacuum pump from a tool rental company


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[Iwannacamp]

One thing I forgot. Do not put anything but refrigerant or the proper oil. No enhancer/miracle cure/sealer crap in there. I don't care what anyone says. I have been working on cars and residential a/c for 30+ years.


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[wrapperman]

I don't think it has a leak. The pressure readings have been this way for 4 to 5 months with no change.
As for sealers and conditioners I do not believe in them. They're just a gimmick to sell something.
I have never worked on air conditioners other than adding a little freon. If it leaks out in a couple of months then I have always taken it to an A/C repair person. My main concern is were these reading off and would it be an easy fix of replacing an orifice.
The compressor is still under the 3 year warranty but I am unsure if the rest of the A/C system is.

[Coach 350]

I would take it to the Ford dealership, as I mentioned ,many on this forum had problems with their chassis A/C and had it replaced. You are still under the warranty. You don't have the equipment to repair it.


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