1996 kenworth w900L a/c problems!!

One is high or low pressure switch and one is bianary switch controls fan and high or low. Sorry can’t remember. Ask kenworth. The one that you jumped to engage fan is supposed to engage when pressure is high.If you run compressor a while at idle it should turn fan on when pressure is high if its good. That’s not to say if it’s a bianary switch that the other function of controlling compressor is good. Basically one is low pressure and one is high pressure except one of them has another function to turn compressor on and off .pressure gets too high fan kicks on then compressor kicks off . Pressure comes down compressor kicks on fan goes off. Power goes thru one of them to power compressor. Without my book I can’t say for sure. But it may be one is fan switch and other is high and low switch Some of the old trucks had trianary switches. I would check for power coming into the other switch and jumping it if it works it’s the switch . Do yourself a favor buy both switches put them on.You change without losing any Freon. If it’s then fixed you can go back and figure out which one as bad and toss the other one.

 

Those two switches are the high and low pressure switches. Check the wires running to them the whole length of them. They are known to break inside the wire covering. Or at the plugs. Do a wiggle test to see if it engages. If not like the other post said one of the switches may be bad. You can screw them off and hook a test light to them and take a small screwdriver and push in the pin to see if they are bad or good.

 

Never thought of that switch test.