I have a 2001 VW Beatle, 1.8 Turbo with about 75,000 miles, need help with AC Fan Controller, question "What should pressure be on equalized system for it to work properly?" getting reading but not sure what it should be to see if this is my problem. Thanks

The "equilized" or "static" pressure really means nothing at all and will vary with ambient temperature. It is no indication of refrigerant level and as long as it is higher than 50PSI, then it's sufficient to engage the compressor.

The only time it really means anything is when your looking at the gauge of a recovery unit, it can tell you if it has any air in the refrigerant that needs to be purged.




78 Corvette Pace Car For Sale-18k mi orig-Florida




(This post was edited by Hammer Time on May 31, 2009, 8:22 AM)

Hammer would have access to more info but if this is the fan to the condenser not kicking on some wait till high pressure is perhpaps 160+ PSI the engage. Some are on anytime A/C is requested I don't have a listing of which ones do that.

Mostly a GM thing but who knows. Take pressures with compressor engaged or not but know ambient temp as noted in front of grille and report that too. Ratio of temp to psi is a known if you know both,

T
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Tom Greenleaf - MetroWest, Boston

Just to be clear on the terminology, when you refer to "equalized", you are referring to SYSTEM OFF pressures.




78 Corvette Pace Car For Sale-18k mi orig-Florida

http://www.chillers.com/...mages/PTChart134.jpg

Hope that shows or clicks. Equalizing takes just a short time. If you know the pressure and know the refrigerant you should be right on for the pressure - when pressures and temps don't match there's something wrong. Many cars no longer use a high pressure port so you have to know the temps.
Just FYI - hope that works??

T
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Tom Greenleaf - MetroWest, Boston

Nice chart Tom...........

Although that answers his question, I believe he is asking for capacity reasons and it doesn't mean anything there. That's the point I'm trying to make to him.




78 Corvette Pace Car For Sale-18k mi orig-Florida

HT - have a better chart that's on PDF only and can't seem to post that one. Shows at what temp/pressure each gas is vapor or liquid too!

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Back to this problem. "Fan controller" and "equalizing pressures when system off mentioned in first post. I may be misunderstanding the problem and was guessing at what triggers the fan for condenser to come on. Some it's by just requesting A/C, some anytime compressor has power to it and some by the high pressure switch such the the electric fan doesn't work in colder weather or if airflow from vehicle speed is enough.

Easy to do but I'm confused as to what the problem is. If fan doesn't come on check for relays, fuses, with everything off and keys out see if fan is frozen up, then I'd take the temp and pressure observations. If there's any question about if the charge is correct I'd start with a known exact charge. It's listed as taking 26 ounces of 134a and 4.5 oz of PAG-46 which is if empty. The oil doesn't come out with a vac and charge all over again but you could add one oz if thought it's never had any work especially at that age.

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Basics. If this had proper static charge #s and nothing else electrical found I'd take the pressures of course. I think VWs use a switch too on the compressor but don't know them all that well. Know that 2/3rds of all A/C poor cooling issues stem from a low charge or if it's been messed with it could be overcharged which should shut down compressor.

Note: Pressures are noted while compressor is engaged - static pressure just tells that some is in the system if it matches the chart and that's about all. It's not like checking tire pressure as refrigerant pressures are totally temp related.

BACK TO THE PROBLEM - IT'S PROBABLY BAD EYESIGHT BUT WHAT IS THE PROBLEM WE ARE TRYING TO FIX?

T
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Tom Greenleaf - MetroWest, Boston