This truck wasnt runing right and wasnt needed so it has been at another shop for 60 days when it came back ac didnt work. Its compresser wouldnt kick in so i ran a hot wire to it and it was a llittle low on freon. I pluged it back in and they backed it up and the compresser kicked off. You can cross the relay and the compresser comes on there is no ground to work the relay. I switched the head unit with another truck and it worked ok in the other truck. Also one time i shut the key off the the engine didnt die right off then another time i shut it off and it didnt die for maybe a minute.
It sounds to me like the thermostatic switch in the evaporator is bad. if the head unit is good and the compressor kicks on when you jump across the relay it is the only other thing in the system. Usually they are right under the cover near the blower motor and not too hard to get at. When the thermostat switch is closed and the head unit is set to turn the AC on that provides the ground for the relay.
Thanks i have replaced the evaporator in a truck like it but didnt remember if it had any thing on it.
It is just a switch with a capillary tube probe that goes in the evaporator, they do quit working for no reason.
It had a unpluged wire on the thermostaic switch. Thanks agin.
You bet!