L2 gleaner air conditioner help

can someone help me with a problem I have on a L2 gleaner.
I can not get the A/C clutch to engage in normal operation. the only way I can get it to engage the compressor is to jump a hot wire to the A/C clutch and it will work. It worked fine last year. I had a leaking line this year so I replaced it, pulled a vacuum for 2 hours and serviced the system with 8 12 oz cans of 134a by manually engaging the A/C clutch.My high side on a 90 degree day is 210 and the low is 18. Can the thermostat in the cab cause this problem or the low pressure switch in the condenser box cause it? is there any way to test the low pressure switch or the thermostat or can I bypass either. the cab is cold with the compressor running.Last year I changed the dryer,expansion valve, and a new compressor.Also 8 12 oz cans seemed like a lot but could not find out how much the system is supposed to hold.Are my pressures ok?? any help would be great.

Do not run it with a hot wire unless you want to blow
somthing up. The system should hold 3.9 lbs.
Assuming you have the original compressor. You
only have 18 lbs of low side you have an obstruction
somwhere. Most likely in the evaporator or the
expansion valve is stuck. First thing you do with any
a/c problem is blow out the condenser cab filters
and evaporator. With proper charge on a 90 degree
day you should have approximate 30 lbs on ghe low
side and the high side should cycle between about
100 and 200 . The high side may not cycle like that if
it doesn't but it is cold and the pressure is between
150 and 250 call it good. After you clean everything
if your pressures are still low and high take it apart
pour flush through each component and blow out
with air. Your electrical problems are easy. There is a
high side switch a low side switch and a thermostat
switch. With the key and ac on and the engin ssd off
you should have power to the compressor if you
dont work your way backwards. Test the low side
switch for power if you have power coming In but
not going out the switch is bad. Same with high side
and th thermostatic switch. If you have more
questions let me know. Aso I forgot if you flush it
you will have to add oil to the compressor. Use ester
oil. No matter what anything else says ester is
universally compatible and much easier on seals
than pagg

When I changed the compressor last year, I removed the heater core and spent over 2 hours cleaning the evaporator core and the condenser core fins. the condenser looked like it had not been cleaned in years.I flushed the system with expansion valve out, then installed the new one,and installed new cab filter. Why did it take 8 cans to bring it up to the pressures I have now?I am going out to check the switches and temp controller now.do you think I have to much refri in the system now, and should I recover some of it?Thanks for the information you have given me I am by no means AC expert just trying to learn how to service my own equipment.

Sorry for the delay I posted this three hours ago and
I guess it didn't go through. Did you flush it with
flush and then compressed air? If so did the air
come through without resistance? It will have some
but when complete it should flow relatively freely.
Usally if you have something like that going there is
an obstruction or the exp. Valve is stuck. If somthing
is restricting Freon flow the low side due to
insufficient flow will drop very low. Your high side
pressure will be fine as long as its over 150. Some
older systems ran that low especially on a combine
to compensate for the dust they ran in. I have seen
some occasions where the valve stuck and when the
compressor kicked on the low side pressure actually
dropped to vacuum. If you have recovery capability I
would pull all the freon out of it and recharge it with
the proper amount. That way you know exactly
where you're at. Then see what your pressures are.
If the high side is high and the low side is low and
you are sure the cab filter condensor and evaporator
are clean suspect stuck expansion valve or
restriction. Combined eat expansion valves because
of how long they sit. If an expansion valve doesn't
move often. Enough they stick. The best way to
check this is to run the system for a couple minutes
and then shut it off. If your high and low side gauges
equalize within 60 seconds it is a restricttion if they
dont it is the expansion valve. Does the compressor
have shutoff valves on it? If you open them all the
way or close them all the way that'll cause faulty
readings or other problems. You turn them in two
turns for maintenance and all the way out when you
are done.

finished with harvest just thought I would finish my forum question, it was either the high or low pressure switch,replaced both of them and it fixed the problem. thanks for all the help.