If you overcharge your AC system will that cause the compressor to shut down periodically?

My system does this after about 45 minutes of highway driving. When I turn it off for 5 minutes and turn it back on it blows cold again? I assume the compressor clutch stops and the freon is not circulating - not sure yet, however.

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Thanks...

 

If the pressure in the system gets too high, it will shut down...and too much refrigerant will cause high pressure....its bad bad bad for the compressor. Weird that it runs for 45 mins before shutting down though. How much did you put in?

 

I vacumed the system down with a new pump for 1/2 hour or so and installed two cans of R13.

In the old days, we used to leave the vacume on over night but I assume this is not necessary. Does 1/2 hour sound like it is enough; could this problem be casued by moister in the system that was caused by not leaving the pump on long enough? Is that big shiney aluminum can on top the AC drier? When should the drier be replaced?

What should the high and low side pressures read on the guages when the proper amount of freon is in the system?

Thanks..

 

1/2 hour of vacuum should be enough time. That silver canister is the accumulator and yeah it does hold the dessicant (dryer). Usually you're supposed to replace the whole accumulator assembly anytime the system is opened up, but thats overkill IMO. Did you replace any parts of the A/C system while open? Two cans of R134A? How many oz cans were they? Did you add any oil to it? Can't remember the pressures off the top of my head, but I can check.

 

my ac compressor blew up and i replaced it, the orfice was overlooked and it was clogged with old metal ****. i re did it and fixed the orfice and all was well, btw i use 3 cans of 134a and itll freeze your nuts


J

 

I don't know what R13 is but I guessing U meant 134A. GM states that to properly evac system you need one hour AFTER system is drawn down to 30", depending on weather and pump, the pressure reading will vary between 27 - 30". There is a sticker under the hood that tells you what the system holds. 1 lbs = 16 oz. therefore 2.5 lbs would be 40 oz. I believe 134A is a 14 oz can but check it. I buy it by the 30 lbs can. A proper charge will be 35 - 45 lbs low and about 150 - 200 lbs high, depending on weather. We normally replace the drier, big shiney aluminum can, whenever we open the system. From your discreption I would suggest your evap is freezing over. Turning off system allows evap to thaw. I would evac system again and make sure you have a full system. Also check low pressure switch. Why did you did this, what did you replace, did you check the oriface tube for crap? Does the system have it's full oil charge? Inquiring minds and all.

 

Those are great questions... Thx...

I replaced the head and cam on the motor about a year ago - so I took the raditator and condensor out of the car. The condensor had AC compressor oil in it which drained while it was sitting in the garage. I then reinstalled the unit, vacumed it with a pump for 30 minutes and replaced the freon with two cans (size was 5 inches tall - the ones you see in K-Mart) and one small can of 134A oil.

The vacume was good and it held a full negative reading on my guages for about 20 minutes before the re-charge - so I assume the system is good with no leaks.

If I vacume the system again, should I replace the dryer since it will be the second time the system will have been exposed to the air? Where can I buy a new dryer for a reasonable amount of dough?

Is the orifice tube you are referring to called the "sight glass"? Where is this located?

Where is the pressure switch and how do you check it?