how to recharge some freon in a 94 c220?
 

the blower is working, I am getting just warm air. I was thinking to get a A/c recharge kit, but i cant locate the low pressure valve.
Can you tell me where is located? maybe a pic?
thank you :) :D

before you start adding freon I would take a low and high side pressure reading to determine the REAL cause of the problem. It might be low freon, but it might not...

Just my .02 :)

Check high and low pressures first to be sure they are out of spec. Undercharging will produce subpar A/C performance, but overcharging will kill the system.

The low pressure port is on the suction hose which is typically larger in diameter than the liquid line and is often wrapped in some sort of foam insulation. It's the one that gets cold and can sometimes be observed "sweating" when the system is running.

Overcharging
 

[QUOTE=gmercoleza]Check high and low pressures first to be sure they are out of spec. Undercharging will produce subpar A/C performance, but overcharging will kill the system.QUOTE]

Just out of curiosity, what happens with overcharging? Does that cause the pressure to be too great and blow out seals? Also, if the high and low pressures are out of spec, would that then pinpoint the problem as being the condenser?

Overcharging can damage the compressor over time. It may not happen immediately, especially if there is a binary cutout switch installed. Those switches usually shut off the compressor at around 435 PSI, long before any seals would blow (unless there is an existing weakness, but that's another story). But higher pressures will definitely accelerate wear, as can generally be witnessed by the much shorter average lifespan of R12 to R134a converted systems; R134a pressures run in the neighborhood of 100psi more than R12 and really put stress on compressors which were originally designed for R12.

Pressures being out of spec can tell you if there is too much oil in the system, if the TXV is plugged, or if there is some other blockage in the system. It can help diagnose faulty switches and even tell you if the charge is simply low (the most favorable scenario). And yes, condensor blockage would also be detectable with gauges though there would likely be other indicators of that.

thanks for the help.
where is the suction tube located?
what tool is needed to check the pressure? whats the normal pressure?

thanks again :) :D :)

Unfortunately, there is not one normal pressure. Rather, there is a chart of acceptable pressures. Even then, it's only a guess, but usually good enough to do the job.

The only way to know for sure is to evacuate and recharge by weight. I don't expect you to want to do that. I wouldn't.

Thanks
 

Thanks for your explanation. I don't have a problem at the moment, but have been immensely appreciative of the level of expertise and willingness to share information here.