Another AC compressor/clutch question

[mlipmd]

I recharged my AC system a year ago and now is again low on freon. (Blows warm air, light flashes, code 09).
Last time I had to jump the low pressure switch to get the compressor to turn on so I could start to fill the system, then after a minute or two I could reconnect it and it would cycle on and off as normal as I filled it up.
A few days ago I did that same thing but only had a small 8 oz. can of freon which was not enough to refill the system. The compressor again turned on doing this and when I put the freon it cycled on and off as I recharged it. And it did blow cold air.

Today, with a fresh supply of 12 oz. cans I again tried to recharge it but now the compressor will not turn on, the clutch doesn't engage when I short or bypass the low pressure switch.
The 25 amp AC fuse seems intact, there is no continuity when I measure across the contacts to the connector to the switch ( I don't know if there's supposed to be), so my question is, did the clutch or the compressor blow or is there anything else I can do to try and get the clutch to engage?
The compressor is not locked up, I can turn it freely with the engine off.

I know - One other alternative than just the cans of freon and the included pressure gauge is to get a proper set of gauges and measure both high and low pressures to see what's happening, but it's obvious the system is low.
Another separate question - if you inadvertently fill it up with too much freon, would that cause the clutch to not engage, for the compressor to not turn on?

Thanks for any suggestions.