A/C relay short.

[mercurygm88]

Ok so back in june when I bought my car the a/c relay was no good I found out from gadget73 that by jumping the two larger blades of the connector it would cycle the compressor and the dash controls would work correctly. Whereas if I were to jump the red power to the black ground it would run the compressor as long as the key was on which was no good. Well I eventually replaced the relay and about 3 days ago it blew again so I tried the jumper trick and it didnt work I can jump red and black and have the clutch run all the time, but I can no longer jump the two larger blades which I believer were solid yellow and yellow with black stripe wires. I can also jump the red power to one of the yellow and it works so this tells me one of the yellow wires is supposed to receive power when the dash selector is on a position which cycles the compressor however it is no longer doing so anyone got any ideas. I hope I didnt short something out somewhere by having it jerry-rigged.

[mercurygm88]

Ok I got to looking at it put the relay back in and put a jumper on the pressure switch I put my gauge on the low pressure side and was reading 35-40psi with the compressor off I kicked the compressor on and it dropped to 13? is this normal? shouldnt it have gone up and built pressure. Is this telling me im low and need to find my leak and recharge or that im fine and my pressure switch is shot? I wouldnt think it would be leaking because when I bought the car it was fully charged with r12 I only converted to r134a because I like the idea of having something that is available and not having to go hunting for unobtanium refrigerant.

[86VickyLX]

It shouldn't go that low. The Pressure switch is designed to shut off at pressures of 28psi and lower. The low side pressure goes down as the system runs, where as the high side pressure increases. If it drops instantly to 13psi when the compressor is kicked on, the system is low and needs a recharge. Best bets are the o rings, condensor, or the evaporator core. Also check out the compressor itself for wet spots.