"""""I am not an A/C certified tech, but I have spent thousands of dollars over the years having A/Cs worked on, on many vehicles."""""

I AM! You've been paying people like me! THANK YOU!

When jumpering, all it does is engage the clutch. The clutch bearing stops turning - so it needs no lubrication then. When it's DISENGAGED that bearing turns. If that bearing is bad it will squeal when DISENGAGED. You'll also see rust and dirt on the front of the compressor - pieces of that bearing and clutch materiel from wobbling.
The compressor crankshaft does all the turning when engaged. The compressor crankcase has oil in it - it has it's own lube inside it - the big plug on the side is how you fill it - shouldn't need it. The oil - use ESTER oil - added in the freon system only lubes the 7 or 11 pistons and reed valves slightly.
If the compressor is locking up - you'll know it.

As long as it's jumpered the clutch is engaged, the compressor will turn. It should not shut off. occasionally the clutch coil goes bad and becomes intermittent - but it's rare.
If it does keep shutting off even when the LO switch is jumpered, measure the voltage to the clutch - at the clutch - should be constant. If not, swap the relay with the horn relay to see if it helps.

Just go ahead and do it - don't let idiots scare you. It really isn't much harder than washing your car!

 

Okay just to be sure- is my low pressure switch supposed to be plugged into anything? The grey and yellow plug isn't plugged into anything, it looks as if it is soldered or connected somehow and taped up (picture included) to the black and red plug that is connected to the black thing by the accumulator. When I jump the grey and yellow plug the front of the compressor starts turning and it stays running now and no more squealing. So with the front of the compressor turning, (the clutch right?) , I can cancel out a bad compressor? I vacuumed the system out in the summer and tried to recharge it and I haven't replaced any parts or anything since then. Should I worry about vacuuming out the system with a pump or do you think I would be fine to just get the manifold gauge set and recharge it?

 

fill it with freon and see if it works ....

 

As to which connector goes on the LO switch - only one should fit - THAT ONE!
Who knows what the other is for.

Your factory Service Manual should tell you. FSM CD's are cheap on e-bay.

 

Then I'm assuming the switch that I'm jumping is wired into the plug that is connected. I'm gonna vacuum and charge tonight.

 

Well I tried to add refrigerant and I used a 1st charge can. The pressure on the low side wouldn't stay constant. When I would unscrew and screw the can, it would jump and then go back down, so I have no idea how I'm supposed to telling I have enough or not enough refrigerant in the system. The air was pretty cool, wouldn't call it cold like an a/c should be. Also, is it bad to keep the low pressure switch bypassed all the time?

 

If the A/C has the proper charge, you won't have to bypass the low pressure switch.

It's there for a reason. It protects the compressor from damage if you have a low or no charge.

 

I'm thinking about getting one of those cans that has the low side gauge attached and just fill it up because the manifold gauge set I rented is hard to read. See if I can get it to the right pressure andbsee if the compressor runs on it's own.

 

1 12oz can is not enough! It looks like it will work once you get 2 cans in.

 

Well I had a little bit left in the system from last summer. I'm having a hard time reading the gauges while filling it.

 

If you are using professional type gauges, close the valve on the yellow hose - and the red one, and open the blue. You'll read the LO reading.

If you are using the DIY cheapo gauge - run the needle down into the top of the can to close it, it will read the LO.
When the needle is pulled out a little, the can is feeding into the system, filling it. Once the pressures are equalized, it'll read the LO. Engine/compressor off max is about 12 lbs, the pressure in the can. Not enough to cause the LO switch to close.

fill it while running, clutch engaged, switch bypassed - then the compressor "sucks' the freon out of the can.
If you are using pro gauges, keep the can upright so it does not fill too fast. Too fast it can hydraulic the compressor.
If using the DIY you can invert the can to make it fill faster - it has a restriction to prevent feeding too fast.

Use the thermometer in the dash vent, temp will drop, then go back up again. Stop filling at the lowest/coolest point - it's full.

Too much freon the temp will go back up.

The Cherokee system takes just shy of 2 12 oz cans. -- 20-24 OZ

If you suspect it's ever had R-12 in it - use ESTER OIL, it's compatible with both R-12 or R-134.

Mineral oil gums up with R-134, PAG gums with R-12

 

Do even if the presssure goes up past 40 when I unscrew the pin in the can, should I just let it suck the refrigerant? When I screwed the pin in an out, the pressure would adjust and stay constant accordingly. I never really saw it raise while the can was just sitting there. It only raised when I screwed and unscrewed the can.

 

YES

 

Should I unscrew the pin all the way and just watch it raise? And if it goes above 40 should I close the blue valve or is the pressure just temporarily shooting up?

 

Are you 100% sure you're on the low side?