Deere 3320 HVAC Blue Knob Function

[jagster936]

I have scowered the internet for an answer to this and haven't found one. These tractors, including my 3320 I just got have a seperate blue and red HVAC control knob. Red controls water valve, blue controls what? It doesn't say anywhere. I have looked in user and also technical manual for the machine. It says how to adjust with a poor picture but was curious how it works so I know how to troubleshoot it or what to expect behavior wise.

It is controlling the air flow across the heater core? Only thing I can assume. I know it can't control the compressor clutch or else that would increase a lot of wear. Does anyone know? It would be obvious to any tech who has had the roof off.

 

[workinonit]

On my 5 series I assumed it controlled a air damper that would blend warm outside air but I don't know that for certain. I know it uses outside air at some point because I have to clean the filters quite often. If it was recirc only it wouldn't need hose filters.

 

[jagster936]

From what I understand at least on mine and many others also the outside / inside air mix is pre set by design. Some outside to establish positive pressure and rest inside.