The point I was making is you look at the system pressure BEFORE you do ANYTHING..........

Jumping the sw as suggested will make the comp come on if low on R , but there are may other conditions that make a comp not come on...If there is pressure , then you could have a simple fuse problem.

The point is you do not want to be adding R to a capacity full system.
An overcharge can kill a compressor.

So, the correct procedure is a gage . If you have 70/80 PSI with the car off, you do not have an R problem of comp start..it is another problem.
But if it does start w/sw jumper , then the comp circuit is OK EXCEPT possible low R OR bad sw.
The problem with jumper sw is if the system is empty and you have a leak on the low side, you are going to draw ambient air/humidity into the system w/jumper and the comp can be operating with less oil than needed.. That is why we verify R charge FIRST....and that is why the sw is there in the first place...they do not want the comp to attemt to start when there is no/low R ..............
In your case , low R is not the main suspect b/c you state that you could not get the R to go from the can to the system w/comp OFF...that indicates the systems equalized/OFF pressure is the same as the can, meaning you have a good charge of R already...if the system were empty, the can would empty into the system until the can and system were of equal pressures..without any aid from the compressor..same as filling a flat tire.
So , if that is the case , the suspect for No Comp is fuse/clutch/etc. from another source.

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A Dalton