So my ac worked fine last year, and this year not so much and its my favorite thing to throw in people's face . Now it's getting so hot that I need to get it fixed. It has freon but I'm not sure how much and I have like 40lb of r12 yes that's right 40lb. There is a copper spike that goes into the low side hose by the passenger fire wall and if I mess with that the compressor will cycle on and off, what is that thing called? I'm going to throw some gauges on it tomarow and see where it's at does anybody know what the psi should be?

Also I took the switch out to see if that was the problem and I determined that it works, but when I took it out the vacuum portion was disconnected, what does that part operate ? I don't see any difference with it connected or disconnected

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So it appears the system is full but the compressor kicks on and off

 

the gauges will tell you what is going on. most gauges will tell you on the face what is the mim and max pressure

 

The expansion valve (expansion block) is located on the passenger side at the firewall between the evap core and the lines

R12 Pressure temp relationship


R134a Pressure temp relationship

 

Thanks that's a great peice of info

 

I'm guessing you have this figured out already but there is a low pressure switch somewhere in the suction side line and when the pressure drops too far it will kick the compressor out. It is to prevent the evaporator from freezing up. Personally I would reclaim what's in it, pull it into a vacuum, and weigh in the factory amount. That way you'll know you have the right amount in it.