Overcharging problems
 

Back to the original question. If you have an overcharged system, not only will it try to blow out the weakest link, it will reduce performance and create other problems. It you have a solid system with no high pressure valve it is even worse.

A few years back, I got lazy and had my secretary's husband (who owned an auto repair shop) repair the A/C on my '67 Mustang. The system got overcharged. Not only did it not cool very well, it sapped the power from the engine and ended up bending the mounting brackets for the compressor.

As Moses said "Let my freon go"

Up-date
 

Ok
I took the 240D today and again tha AC was less than impressive. Although I did'nt put the little tmp wheel on max as I guss I should have. When I got home I put the low pressure side gauge on to check the readings. With the temp wheel on mid range or so the low pressure side drops ot about 30 and then disengauges the compressor until a pressure of about 75. With the wheel on max cool it drops to about 20 and yes it has cold vent temps but it did not kick off the compressor until I backed of the temp wheel on the dash. I'm wondering if the pressure switch should kick in sooner than a pressure of 75. It sure seems like it should as the vent temp gets far warmer than it should when it kicks off. Or am I just beating my self up:behead:

I am pretty sure that there is no switch in the low-side line, so that's not it. Check the high-side pressure to see if that switch is cutting out the compressor.

No Low Side Pressure Switch
 

That's correct their is no low side pressure switch!

As I mentioned previously the temp. and pressure switches is located on the dryer. The dryer resides on the High Side! :D

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134-a does not get as cold as R-12 to begin with so if you are comparing the two and expecting the same result it will never happen. This difference will be even grater as outside temp rises and if the system was running poorly to begin with. :rolleyes: