Hi folks,

So I tested my AC compressor by jumping the low pressure switch and it seemed to run with no problems, and silently, too - I was like, "wow, it sounds like it's new!" Turning the compressor by hand, too, there was no noise or resistance, and I heard bubbly noises in the receiver dryer. So, on the advice of a friend of mine who is an experienced mechanic, I used a charge kit and some R134a to further investigate my AC system.

The gauge on the low side told me that the charge was very low, near 0. I added some coolant from the can for like 15 seconds, and checked the pressure - it was very high, like 45psi. The compressor kicked on 45 seconds later, and made a sound like there were ball bearings in there. It only ran for like 2 seconds, and the pressure on the gauge began to drop to around 25psi. It climbed up to 45, compressor kicked on and off, pressure dropped, then the pressure climbed again, ad infinitum. With the AC off, I read 75psi steady.

I have never charged AC, so I don't know what to make of the bobbing needle on my gauge. Why would pressure steadily increase without the compressor on? Do I need to adjust the pressure switch to kick on at ~30psi?

Thanks for your advice. Please don't berate me for not visiting an AC shop, I didn't have the money and this was more an investigation than a repair.

Ari