Do all factory ac systems have this ??

[67cheby]

some i look at dont and some do any info someone can share on this for me, i am converting mine to factory ac but this looks like a pain to put in can i do it without it

[Lebowski]

That appears to be a vent door to allow the ac to draw in outside air, with it closed it would recycle the air inside the cab. It would be preferable to draw outside air for the sake of freshness.

[Lugnut64052]

Setting an air conditioner to max cool should make it recirculate. The system dehumidifies the cabin air in the process of pulling the temperature down. If you're pulling outside air, the system has to work harder because it's constantly sucking the moisture out of the outside, humid air that's coming in, plus it'll never get as cold.

Air conditioned cabs had the recirc door in the cowl. I would suggest hunting up the parts to make that door functional. Your air will work better.

[JimKshortstep4x4]

As Brett indicated, recirculation is needed. Here are three pics of the setup. It will not be too difficult to install the door and its vacuum operator. If your cab is not AC, it will still have a dimple where the shaft is to be located on the inside. I believe that LMC carries all of the parts needed.

My pics have the spring in the wrong hole but your pic has it in the right one. (I changed the spring around when I was putting the cowl clip nuts on, later).

Jim