Problem began when cab heater/AC fan decided to run continuously on high, switch on panel had no affect
Got to a point if I wanted heat it was required I turn on AC button
Replaced HVAC control module/switch plate on dash
I now can turn on/off the fan but no heat.
When I turn on heater I’m hearing clicking from the fuse panel passenger side in front of seat on dash.
Im thinking it’s a relay that controls opening and closing of the door, which allows heat/cool in the system
Freightliner is not real good at identifying fuses/relays pertaining to the HVAC systems
Am I anywhere close on my thinking with regard to the relay ??