Air conditioning override off control
Marcopolo saw a reference I made to an AC override off switch we added to our 07 C190P, and suggested a new thread describing it., so here it is. I didn't find any pics, but there isn't really much to show anyway. The goal was to get the ventilation system to work, without the AC running, in more than the floor heat and vent positions.
It took about 3 hours with the hardest part being getting the dash front panels off. Very tight clips and the factory manual is not totally correct in procedure.
The good part is that it is just a single wire to splice into and add an on/off switch. They use one wire from the heater control to the power control module to signal for the AC to run. It seems to be totally independent of the other control functions. It is also low power as it is a signal wire, compared to going into the compressor wire which is pretty hefty load, and might trigger an error code (calling for AC, but no running compressor). or it might speed up the idle.
I added the switch into the blind switch knockout next to the passenger airbag switch.
Since this interrupts the AC signal line for the entire control, you can shut off the AC in any setting. I was looking mainly to kill it in defrost and floor/defrost, but the possibility of turning the AC off in max AC mode is interesting as it gives you the opportunity to use recirc air (max air) while running the heater. That is a big help in getting a big area like a van warm quicker.
We have had it in place for 3 years, and would not be without it. Being able to bring the fresh air, no AC, in through the defroster vents makes the cab much more comfortable than other positions in moderate weather when you don't need the AC.