2004 Corolla AC problem

My compressor wont engage - what's the best way to test for what the problem is? I bought a pressure tester but it's inconclusive because I don't get a reading on it or my 2003 corolla which has a working AC. Is it worth just pumping in some 134 to se if that cures the problem?

It is most likely a blown fuse in the clutch actuator circuit.

It is most likely a blown fuse in the clutch actuator circuit.

OK - Thanks - I know I should have done that but it's so hard to get to - I'll do that next.

I have a 2003 to compare to. Presore gauge on 2003 shows 40 psi - 0 on 2004. I added some to 2003 - but wouldn't go in on 2004. Any suggestions on that.

AND THANKS AGAIN FOR YOUR REPLY!

Are you adding the freon as directed by Toyota in the shop manual?

Are you adding the freon as directed by Toyota in the shop manual?
first thanks again for your reply. I do not have a shop manual. I run engine with AC on max windows open for 5 minutes. on 2003 can gets REAL COLD AS FREON GOES INTO LOW PRESURE FITTING - BUT NOTHING HAPPENS WHEN i DO THE SAME THING ON MY 2004. ???

Is your ac compressor on the 2004 turning? Does freon go into the system (hiss?) - does the freon can get cold? If the compressor turns, what does the sight glass look like?

Is your ac compressor on the 2004 turning? Does freon go into the system (hiss?) - does the freon can get cold? If the compressor turns, what does the sight glass look like?
Thanks again for your reply. The compressor pulley turns but clutch does not engage. Can't add Freon. There is no hissing sound and can is warm. Not familiar with the sight glass - also will try to locate the low pressure cut off switch.

A low pressure switch will prevent the clutch from engaging if there is too little freon. If you don't have a gauge set, add a can and see if it kicks in. If so, it was low on freon and you likely have a leak somewhere. Some cans even have a gauge on them. They're crude but will tell you if you're too low.

If it is low but not zero, add a can of freon with leak detection dye. Go for a week then follow the plumbing to find where the dye leaks out. If it is zero, then the system has likely been contaminated with outside air and must be pumped down first with a vacuum pump before adding freon/dye.