Manually selectable recirculate?

[Sir William]

I have a 99 with the automatic climate control. I also have a partially clogged front heater core (surprise surprise). When it's below about 30 out, the only way to get heat up front is to put it on max a/c then turn the temp to 90. This closes the door that lets fresh air in and puts it in recirc mode. However as soon as you switch to defrost or any other setting, it mixes in cold outside air and becomes uncomfortable really quickly. This is one of the dumbest things I've seen in a HVAC setup because it should be up to the people inside to choose whether to use inside or outside air.

So my question, is there there any way to add a switch in somewhere so I can leave that door closed or make it close, etc.? Surely somebody with a full schematic/wiring diagram can lend an idea or two? Thanks!

 

[stamp11127]

You would need to supply vacuum to the white line that controls the air inlet actuator or a second line directly to the actuator. All the other modes do not require a vacuum.
It can be done with a solenoid but they aren't cheap.