AC question . . .

[Fastereddie]

Something is very haywire. Or I'm retarded, which is likely also.

I'm waving the white flag.

Lol. It's the heat man, it'll make you delerious.

 

[Blue85]

when the compressor kicks off, it climbs above the limit, then when it kicks on it drops below the limit.

Given this, you were connected to the low side. Sounds like you were using one of those Wal-mart cans with a fill-hose and gauge built-in? If you were on the high side and the compressor kicked in, it should peg the gauge instantly. Also possible to blow the hose or the can. Now before the compressor cycles on, both ports are almost the same thing and you could add some refrigerant until the system pressure equals the can pressure (in normal charging, the low pressure from the compressor suction helps empty the can). But without any numbers on the gauge, you don't know what it's calling "over-filled". Now if your gauge doesn't move but the compressor is cycling, then something is funky.

The gauge set says it's for R-134? It's possible somebody retro-fitted for a different refrigerant. Technically they're all supposed to have different fittings. The standard fitting for R-134 has never changed.

Yeah, the compressor just doesn't stay on long enough to get a read. It's literally cycling every 2 seconds or so.

This is the classic symptom of low refrigerant. Pressure is maintained in the low side by liquid refrigerant boiling. When you run out of refrigerant there's no gas coming to keep up with the compressor so pressure drops very fast. With a proper charge, it will take several seconds for the pressure to come up after the compressor turns off.

 

[Phil513]

Given this, you were connected to the low side. Sounds like you were using one of those Wal-mart cans with a fill-hose and gauge built-in? If you were on the high side and the compressor kicked in, it should peg the gauge instantly. Also possible to blow the hose or the can. Now before the compressor cycles on, both ports are almost the same thing and you could add some refrigerant until the system pressure equals the can pressure (in normal charging, the low pressure from the compressor suction helps empty the can). But without any numbers on the gauge, you don't know what it's calling "over-filled". Now if your gauge doesn't move but the compressor is cycling, then something is funky.

The gauge set says it's for R-134? It's possible somebody retro-fitted for a different refrigerant. Technically they're all supposed to have different fittings. The standard fitting for R-134 has never changed.


This is the classic symptom of low refrigerant. Pressure is maintained in the low side by liquid refrigerant boiling. When you run out of refrigerant there's no gas coming to keep up with the compressor so pressure drops very fast. With a proper charge, it will take several seconds for the pressure to come up after the compressor turns off.

Yeah, after looking I'm pretty sure I was connected to the low side. When the compressor kicked in, the pressure dropped.

It was one of those cans with the long hose, but from O'reilly, but probably same stuff.

There is a label on my fan shroud that says it was converted to R134. When I first bought the truck I took it in and had it recharged, they never said anything about it being not R134. After that it worked for a long time.

It probably is low refrigerant. I'm just worried about overfilling it, and I don't trust the gauge on the refill canister. It was bouncing up and down when the compressor cycled, now it just sits still in the middle of the overfull section. I guess I could keep filling, I don't know what potential dangers are of overflilling.