Chad05TL

I have a question. I was adding some R134a to my system. It was not real low, but on the lower side of the "full section" of the meter. It's one of those cans that comes with a meter on it like from walmart or o'rielly's, So, I snapped on the connector and read the pressure and it was fair, but I added some in, and while the A/C was on and the compressor was engauged, The pressure read lower then when it did when the compressor cycled off. The weird thing is that it cycles even when I initially turn it on and its no where being cold air yet. So why does it do that? It needs to stay on more. I know cycling is normal but gee, why does it shut off before its even cold yet. And secondly, should the pressure be going back and forth like that on the meter as a result of the compressor clicking on and off? And thirdly, how the heck are you suppose to charge it when the direction says turn the a/c on max and then read the pressure and fill if needed? It keeps bouncing around so I dont know which reading to use... The guage goes from "just barely in the filled section" to "almost overcharged" on the meter when the compressor cycles on and off. So, when its on, pressure goes down just the minimum "filled" line, and when it shuts off, the pressure approaches the "overfilled" line. so thats a lot of jumping back and forth.. It cycles about every 20 seconds.. I may just time it with a stop watch.

Turbonut

iTrader: (1)

Yes, the pressure will rise an fall as the compressor cycles on and off. The low side will drop and the high side will rise while compressor operating. When off, the low side will rise and the high side will drop to a point where the system is equalized.
Working on the system is dependent on the ambient temp as when hot and humid, system on max coldest setting, the compressor will run at longer intervals and readings will be easily read. I've only worked with gauges to read the pressures and adjust accordingly, so it would be guessing to make a decision as to what the problem, if any might be. Get a stick thermometer and put it in the middle outlet with the system on max/high to see the temp of incoming air. That will also change according to ambient temp/humidity.