9400i a/c problem

High and low pressure switches? There are actually a lot of things it could be. Even a dash switch to power the relays.

 

Did you open the valves under the hood? Could be the actuator not opening the door to allow the cold air into your duct work. Its located under your pass. seat next to the blower, will have metal rod connecting the door to the actuator. Just a couple easy things to check

 

Does your truck have an APADS module?

 

Check the thermastat switch in the box by the blower motors. If it is ok check the high & low press. switches on the expansion valve.

 

APADS module basically runs the a/c system. Most trucks have them, some do not. You really need to know if you have one or not because the wiring and sensors are different and in different locations, so what the others here are saying may be totally useless and just wasting your time. If you have one, it will be mounted on the firewall on the drivers side, usually on a bracket right in front of the tractor protection valve. It will have a red and green LED on it too and one of them should be on or flashing with the key on to indicate status.

 

Try to jump your high pressure switch. It should be near the compressor somewhere in the line.