Can't add refrigerant to car.

[Turbofiat124]

2003 Subaru Baja:

My AC is not working. I stuck a temperature probe in the vent and it's not cooling at all.

It was working last fall. My guages seems to indicate the system has lost all it's refrigerant.

The engine rpms drop a bit when the AC button is pressed. I believe it's just the fans kicking on. Due to the serpentine belt cover I can't tell if the compressor clutch is engaging.

I hooked up a set of guages and turned the AC on. The low side is zero. I think the high side was 100 lbs .

I tried adding a can of R134a but the system won't take it. I turned the can upside down BTW.

I tried one of those simple tools that has just an inline guage.

Still nothing. I'm thinking the low pressure switch on the receiver/dryer is not allowing the compressor to kick on and that's why I can't add refrigerant to the system.

So do I need to jumper the connectors with a paper clip before I can add refrigerant or should the system take it otherwise?

I've got an AC vacuum pump. Even though the system has never been opened, if I pull a vacuum on the system for 30 minutes, would that help?

[Cornbinder89]

Many modern cars do not use a pressure switch, they use a sensor for the climate control ECM, do not jump anything until you know what you are dealing with.
100 psi on the high side would be enough for the system to turn on, if that reading is correct.
Sound like your connection aren't working.
Just adding refrigerant without knowing how much oil is in the system is a good way to burn up the compressor.
Also, new self-sealing cans need a different can tap, or an adaptor to work with the old piercing type can taps. Look at the top of the can, if it is metal all the way across the spud, you have an old pierce type can, if there is a hole in the center already, it is the self sealing can and needs the new type can tap, or an adaptor to use your old tapper.

[Tom Greenleaf]

Welcome: You may not be able to add refrigerant for several reasons, one is the fittings don't cooperate with hose used probably so in fact. What made you think it's low on charge and could handle a whole can if you could? You'd choke most systems and destroy them if you could especially charging by liquid for DIY that should be never.

I can try to post it here or just ask what static pressure do you have now and at what temperature under the hood sitting still, engine cold? I just want like a tire pressure check. If temp in F. is in 70s > 80s the pressure should be that or higher. That just means system isn't empty. If lower than temp it essentially is no point in much except finding the leak first then assess the system to see if it's hopelessly trashed or can work with it.

Once leaks are known (as best as possible) ruled out a vacuum to max, well held then charge to exact listed weight underhood is next but you made a comment that needs clarifying!

You said engine RPMs go down with A/C request? It shouldn't ever do that so needs to know why. Compressor itself if engaging is so frozen up now it's dragging OR car's ECM can't change RPMs to cover normal load expected in memory stays the same unless you reset it OR if now it's choking on too much refrigerant??