I was renovating the A/C completely in 2008 including the evaporator (painful) and charged the system with 2.8 pounds R12, got readings of 200/25psi at 75F and 45-50F at center vent.... but to be honest the cooling was never great. Today I am measuring 60 degrees at center vent with a 80-85F ambient.
So it could be that the system was never charged fully which is amazing because it should work with less than 2.8 pounds (2.5 for instance as Brian pointed out). maybe the reason is that I was loosing freon when changing the cans.... or there is air in the system? Or why do I have high temperatures at the vents?
In addition I might have lost some freon over the last 2 years.
How can I prevent overfilling? Martin
Quote:
Originally Posted by leathermang
The MB FSM on AC warns against using the site glass for this procedure.
SLOWLY adding freon while checking the temperature at the vents is pretty safe since it will run just fine many ounces less than maxed out...you do not want even one ounce over or it will cause your system to be overworked in short order.
So that ' RANGE' was not being imprecise... but being honest... and safe....Also, sometimes the total volume of a system is change by things like which condensor,etc was installed... so giving that Range of amounts of refrigerant was proper.
I would suggest when having to add with no way to measure weight.. that some means of forcing air into the front of the radiator/condenser is needed... like a squirrel cage fan... right up at the front of the car...
By slowly... I mean once the system has enough charge to stay operating... to keep the cutout switch from cutting out... then a couple of ounces added at a time then STABILIZE for 15 minutes at high idle WITH that forced air at the front...
Once your temps in the center vents with the fan on LOW... get to anywhere near 40 degrees I would stop and enjoy the cool air.
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