I have a set of freon charging gauges for charging R-134 vehicles.Im tring to find out the proper way to use the gauges myself when charging a system with freon. I know you hook up the low side(blue)hose to the low pressure and the high side(red)hose to the high pressure side on my vehicle but how do i know what valve side i open such as do i open just he lowside(blue) or do i open just the highside(red) or do i open both sides when charging system with new freon? and also what is a good pressure guage reading on the lowside and the highside of the guage dials?
Its freet to use and you can diangose your car online and talk to real mechancis who will help you trouble shoot your problem and lead you to local help.
is the system completely empty(any pressure)? if so,the leak should be located and repaired first. is the compressor short cycling(turning on and off)? i would highly recommend getting an a/c beginners manual,pressure/temperature chart,and a infra-red thermometer. however there are people who use this method(use at own risk).
most just say to put it through the lowside(car running @ medium idle) in vapor form(read the can as to hold it rightside up,or down). till the low side line is "beer can cold". they also say that you may put the can in a bowl of warm water to allow the the vapor pressure to raise slightly. they would suggest that if you partially cover the condenser "in front of the radiator" with a piece of cardboard this would simulate driving on a +90 degree day. those particular people would feel that 35 psi on low and not over 275 psi on high side would be approx.
screwing around with the A/C system can be dangerous, unless you know what you are doing its best left to a person who does this kind of work.
some years ago when I worked in a shop and R-12 was in common use. we use to charge a system with the small cans of freon. The "cool - stupdi" thing to do was if you had a little freon left in the can you would unchook your guage hose off the quick connect can connector (it has its own scharadder valve) so the pressue in the can was maintained... you then let the can loose from the quick-connect and the fun would start... can would spin around and dance around on the floor... that is unless there was a good bit of freon in the can and then you had a rocket...One of us let a can go that was about a 1/4 full and it hit the floor and then went strait to the roof and punched a hole in the roof inslutation in the roughly fwo story shop building. Very lucky no-one was hit.
The danger in screwing with the high side on freon is that the high side pressue on the system is greater than the pressure in the can and you can have an explosive event if you connect the hoses wrong, you try to charge the wrong side (high vs. low).
Screwing with the A/c system can be very dangerous....!
when the A/C system is running the pressures vary a good deal from the low side to the high, this is where is most important to have the hoses connected to the right ports, and operate the valves correctly. I don't know what the values are on the r134...i think the values on the old r-12 systems were around 30 on the low side and 270 or so on the hgih side with the system running. My memory is not the greatest and that was a few years ago. R-134 pressures are different I believe.
Just wanted to caution you about the A/C system. There are some dedicated manuals on A/c systems. I know Snap-On use to have a pretty good one.
the "partially covered condensor" resricts the air flow slightly and makes the system react less efficiently. this would be similar to the way the system is less efficient on a 90+ degree day versus a 70 degree day. the pressure would raise enough to be an example of how the car would perform in warmer temeratures. some just pull power to one of the fans, if it has two fans.
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