My A/C has not been blowing cold since last fall, haven't used it all winter for obvious reasons. Bought one of those A/C Pro canisters and charged to the recommended line. But even with the canister disconnected, the system continued to build pressure, so much that the compressor locked up for a second before i shut the truck off. Everything is fine, took the truck for a drive (A/C off, didn't want it to blow or what have you), and it ran fine. Just wondering what is causing it to build excess pressure like that, my first thought is that i got a clog somewhere. And i do not have a proper set of gauges, my friend is going to let me borrow his at some point. I'd appreciate it if someone could point me in the right direction before i go further. 1990 4Runner 3.0 Thanks guys.

 

I would check the drier (coke can looking thing that's inline), or the orifice tube (small screen type thing also inline). Never a bad idea to replace them occasionally anyway. They can clog if something starts to come apart, such as a hose, or compressor...

 

Thanks for the advice Rok, i was considering replacing those things since they are relatively cheap, and semi accessible. The system blew cold when i put the freon in, and then the pressure just spiked, so i was pretty confused about what was going on.

 

A proper set of gauges can be had as a loaner tool from autozone.
Without the gauges you are just guessing and hoping and that's no good, especially dealing with a/c.
If you open your system you will need to draw vacuum to evacuate moisture, autozone also has vacuum pumps as a loaner tool as well.

Good luck...

 

Thanks Frank, didn't realize they rented them.

I forgot to add, the compressor never cycled, it just stayed on the entire time, I'm thinking maybe my high pressure cut off switch is bad?

My apologies admins and tech-ers, i didn't realize i posted this in the wrong sub forum until just now, please feel free to move.