a/c giving me fits!

[IH8BOWTIES]

I posted before about my a/c cycling on and off for about 2 seconds and 5 seconds apart. Tried adusting my pressure switch. Hooked the guages on it and it was between 250 and 300 on the high side and the low side never would get below about 75. It had all the indications that it was low on freon but it won't take a charge. I'm no a/c guru but I've never had a problem charging a system until this. I just put a new liquid line on my neighbors 93, charged it up and presto, you could hang meat in that friggin car! Mine has it in for me. Could it possibly be overcharged? I'm running out of answers, money, time and patience. Someone throw me a rope..........Thanks

 

[jrichker]

Was the system vacuumed down before the refrigerant charge was loaded? If you open the system or it loses all the refrigerant, it must be vacuumed down to remove all the air and moisture.

 

[IH8BOWTIES]

It was on the initial charge. Hasn't been opened since.

 

[dcurtis]

Vacuum it and try again

 

[HISSIN50]

If the compressor is cycling, double check for an issue with your gauges or the LPCS.

 

[IH8BOWTIES]

Pressure switch and guages are both new. Thanks for the help. I think I will try to vacuum it down again. We charged it with 1.75 lbs which was called for. It worked great for about 2 weeks then started acting like it was low on freon. System is holding pressure so I figure there is no leak. Checked pressure one night after work and again in the morning. No drop. I opened both valves on the guages and let both sides even out and it held all night. Thanks again........

 

[jrichker]

You need to pull 28.5" of vacuum for 45 minutes. The cheapie air powered vacuum pumps are not adequate to do the job.

My current vacuum pump is a refrigerator hermetic unit (motor & compressor in one unit). It was a freebe from a local used appliance store. I bolted it down to a piece of plywood & soldered a 1/4" flare fitting on the suction line. It works great, pulls 29" of vacuum in about 10 minutes or less. I have used it several times and have had excellent results.

 

[IH8BOWTIES]

Thanks JRichker. You've got a lot of good stuff. I'll have to look into the homemade vacuum pump. If I can't find one, I know that Harbor Freight has some for about $79 that'll pull 29hg no problem.
I have a mechanic friend (don't we all) that told me to look at my condensor. I took a hose after it and it did seem to help. Clutch engaged for a little longer and it seemed to get a little cooler. Of course the sun was setting and the temp dropped to about 96. I may have it recovered and just go ahead and change the condensor. Might as well, I've changed everything else. Thanks again..........