AC settings/fan blower

[Chub3006]

Good morning all, I have a question reguarding the hvac system. I’ve done some reading and have gotten some mixed ideas so here goes. The truck is a 1977 k10 with factory air after having it for about 10 years I finally decided to get the ac going, it went pretty well just had to replace the line set. Now on to the questions 1. The fan blower works on all speeds in vent bi-level heat ect, but when I switch to max AC it automatically switches the fan to high, some folks said this is normal but I have had squares since I was 17 but never any in the 70s era so maybe they are different. 2. The fan stays on a really low setting even with the lever to off position. Here again some say this is normal some not. 3. The last question I had was I took out the factory passenger kick panel vent for a speaker replacement and plugged the line would this mean I would always be on recirculating air? And do I need to fit it back in there also some say there is a fresh air actuator that works with the kick panel actuator can anyone confirm this on an ac truck? The air works pretty well and definitely cools it down but I’m wondering if I need to put that kick panel in to work properly. Sorry for all the questions but if anyone has any or all of these answers I would greatly appreciate it thank you Matt

 

[75gmck25]

I’m not sure when GM started using continuous blower flow on the low speed all the time, but AFAIK it’s a stock feature. Blower high on Max A/C was also standard on my ‘75, even though my control panel is made differently.

FYI for others - on my ‘75 I do not have a max A/C position, but the temp slider has a slight indent just short of max cold. At that first indent I get outside air for A/C, and normal blower speed control, but if I push it past the indent to max cold I get recirculated air and only max blower speed.

If you plugged that kick panel door you will never recirculate inside air. On recirculate mode it closes up a door outside in the cowl area (shuts down most outside air) and opens the kick panel door to pull air in from the cab.

 

[Chub3006]

Thanks so much for the detailed post so if I leave it as is with just a hole in the pass kick panel it should get as cold as possible I’m thinking? My bi level setting would sorta be like your 75 in that the fan control works. Thanks again!