This is under the heater /ac box on a t800 KW . What is it ?
If its in the engine compartment on the firewall by the heater box- that's where my fan switch elec over air solenoid sits.
That makes sence. This truck will not hold air very long. The air tanks were both leaking i replaced them and this thing is leaking some. As fast as it leaks i think i should hear were it is leaking from but i cant.