911 a/c recharge

[WCAM46]

I have to top off the R12 in my '86 Carrera. I have hose & can of freon. I know to hook up to the low pressure side - the larger hose, which is the lower tap, right?
Am I correct in remembering that the a/c unit must be running?
Any further instructions/advice gratefully accepted.
Bill

[RSTarga]

car must be running a/c on hi engine lid closed

[Jim Sims]

Wear safety goggles, charge outdoors, do not invert can, engine running 2000 RPM, engine deck lid down. Make damn sure you're connecting to the low pressure or suction side of the compressor; with R12 fittings you can get it wrong and explode the refrigerant can. If you are unsure, get knowledgeable assistance. You can seriously hurt yourself.

[WCAM46]

I did as indicated, hooking up to the bottom tap, which has the larger hose, assuming this was low pressure, inlet side. Nothing happened - no fluid transfer. Am I incorrect in my assumption that the lower tap, larger hose, is low pressure?
Bill

[Tigerrat]

Somewhere on the comp. should be an S for suction, D for discharge. The suction side comes from the front of the car, the evap. The discharge goes to the decklid cond. It can take me 20 min. to empty a can. If the can gets cold the freon is moving out. Be careful.

[WCAM46]

The side I used was the one NOT marked D, so I was correct. The can did not get cold - I shall try again tomorrow - thank you

[bob deluke]

Bill;

You should have a set of refrigerant gauges hooked up to the suction/discharge ports. Without knowing pressure in system, you are just guessing at conditions. If your tank temp/pressure is lower than system pressure, the gas from the system will go into your R-12 tank. You need to have a higher pressure in your R-12 tank than the system pressure. Without gauges, you are taking a w.a.g. Nothing like overcharging a system and having it seize the compressor! If you are unsure of how to charge a system, take it to someone who knows what they are doing. R-12 is very expensive and almost non existent today. You cannot buy virgin R-12 anymore, most is reclaimed and if not done by a reputable company its garbage.

[T77911S]

if you are using the tap that goes on top of the can, the valve has to be screwed in to puncture the top, then screwed out to let the freon come out of the can. put the can in hot water, it helps it go in.

as said above, you need gages to know if you need some and when you have enough in there.

i may be wrong, but i thought on some of the old copmpressors there are service valves.