Compressor Inlet Temp sensor

[Chamberpains]

If you had that brass plug in port C (exhaust) then the fan clutch would never engage because the air from the fan clutch to the solenoid is trapped. Your truck would engage the fan when you 1st start up the truck for the day because during the off time the entire system leaks out somewhere. You may want to find that leak.

More than likely if that plug was installed for a long period of time, the solenoid simply froze open internally from lack of proper mechanical movement while the electrical solenoid kept trying to open to exhaust the air from the fan clutch.

This isn't the 1st time I've seen this. Its actually very common. On the factory solenoid there is something that looks like a plug. It's not. Its an actual exhaust fitting. Some guys think it's a plug so they simply install a plug, which is wrong. Other times the solenoid kit comes with the plug for a 3rd type of install and guys don't follow the directions so they think just because it comes with the kit, they figure they should use it somewhere..... wrong!!

Read and follow the instructions closely.