Quote:
Originally Posted by Manarius
The pressure doesn't really change all that much. It stays right around 40PSI (at least, that's what I got on a 70 degree day). If you just get a can of refrigerant with a pressure gauge already, all you have to do is empty the can in until you meet the correct pressure in the system. It should take about 21-25oz of R134. If your are is equipped with R12, that's going to be a problem because they don't really sell R12 anymore.
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to charge the system is making note of the frost on the low side line.
Of course, the engine has to be running and the air conditioner turned on to cold (real cold.)
If the compressor clutch doesn't engage because of the low pressure switch, adding refrigerant will increase the pressure and make it come on.
If the compressor clutch engages and starts pumping, you should get some frost developing on the low side line as you charge the system with the refrigerant. If you should over charge it, the high side safety will cause the clutch to disengage. and clutch will go on and off as the pressure in the high side fluctuates, then just purge it a bit.This is of course, after the frost has began to develop. It would be possible for the low side safety to disengage the clutch with the system undercharged, because of the engaged compressor clutch pulling the pressure down too quickly. (not likely, but possible) If you have frost on the line, you are probably getting close.
Pressure in the system will vary a lot when it begins cooling because the high pressure side gets pretty hot and expands the gas. (refrigerant)
It is possible to get R12.
Real costly. A few years back it was $20.00 for 30 lbs. Now, since the Gestapo, US Government), got into the game, it now is about $1,400.00 wholesale for 30 lbs.
However R414A is a direct replacement for R12 with no problems...and more readily available. (what I use) "just pour it in".
Hope this helps,
Keith