Ac compresser runs does not click off and on put new clutch switch on put in about 20 ounces of freon . no cold air. any ideas?

Did you then draw a vacuum and charge the system?

I sure hope you don't mean 35 lbs of freon !
When the ac compressor is running, the low side will read 30-45 psi under normal conditions. The high side should be around 250psi.
You need to be able to check both low and high to see if the system is full of freon. It holds around 4 or 5 cans total depending on make and model. Thats about 3 lbs.

Usually low on freon or a faulty pressure switch.
Could also be a problem with the ac clutch on the compressor.

If this was happening to me.... I'd goto an airconditioning re-gas centre and get them to check for gas leaks. In my old commodore the Evaporator Core was leaking and causing some of the issues you have mentioned.

The pulley on the compressor is always running when your engine is running, but the only time
it compresses the freon is when the clutch engages, if the compressor's pulley was not turning,
it would have already snapped a fan belt or your serpentine belt. voltage runs from your fuse box
thru your air condition switch on your dashboard to a low pressure switch that is located at the
accumulator a long cylinder,close to the firewall under the hood or close to the condensor, front
of the car. the switch detects freon pressure in the accumulator, if there is freon pressure, the switch
will stay closed and allow voltage to go to the compressor clutch to engage it and compress the freon,
if there is no freon pressure the switch will open, and there will be no voltage to air compressor, its a
saftey switch to keep your compressor from getting damaged.its possible that the switch could be bad
it may not have voltage at the switch, or it may be open because there is insufficient freon pressure.
check and make sure there is freon in the system.check for voltage at the low pressure switch if you have freon in your system and voltage at the pressure switch, set your ac on high, pull the molex off
the switch, and jump it out with a jumper wire, if the clutch engages and your car starts to cool, just
replace the switch. if the clutch engages but does not cool, then your ac system has some blockage
in the lines. if the clutch does not engage at all then it would be the compressor clutch. good luck!

Sounds like the freon was pretty low.The pressure readings are pretty low indicating possibly a weak compressor or freon is still low. Does this have rear ac as well?l You probably should have evacutated the system and put it into a vacuum. A very useful tool would be to inject a uv dye oil charge into the system and let it run with the ac still cycling which can still be done prior to evacuation.If there any leaks present the dye will seep out the leak and be easily detectable with a uv light.

best diagnostic method is dual head gauges. balanced pressure between low and high side in the off position is aroung 90 lbs. running low pressure is 20-40 lbs and high pressure 160-200, is the compressior not coming on? does it stay on, or click on and off. either might mean the freon level is low. try unplugging the low pressure switch on the low side supply line and shorting the pigtail wires together with a paper clip. does the compressor stay on now? if so and the air is warm or cool, freon is low. if the air is cold that switch is bad. if compressor still won't come on the list of possibilities grows longer: compressor, comp fan clutch, AC relay, restriction at several places... repair shop time...

when you day the air goes on and off i assume you mean the compressor goes on and off. that is what moves th freon through the system. if you are getting cold air when the compressor is running then the problem is that the compressor is stopping and that would be because a pressure switch may be bad. it is possible that model has a thermal shut down too say if the compressor was low on lubricant and was overheating when it does run. but if it is a pressure switch that is failing and they do, it is an easy fix. if you follow the ac lines you will find the switch.it is small about the size of a sparkplug-attached to the ac line and will have a connector with two wires. if the car is running and ac is on but the compressor is not turning remove the connector and jump to two wires. the compressor will start running if the switch was bad and we are sure there is a good charge on the system. if you are getting cold air there should be a sufficient charge to close the switch. these switches can be removed without losing any freon. there is a valve below them that will shut off when the switch is removed. then all you have to do is get a new one and screw it into place,apply the connector and you are done. if that is the problem. hope this helps please let me know and good luck

yes alow presure switch is likely on GM and it could be out of freon ,safe way to tell is to put a set of gauges on it and it will tell by passing the low side switch will just destroy the compressor if it is out of freon

The frosting of the line is normal. Did you use a gauge set when charging the unit? AND, most important, Did you evacuate the system before putting in the freon? Very important.What was your final low side reading and your final high side reading?