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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: 75scottsdale on September 30, 2013, 01:47:20 am

Title: Help with HVAC?
Post by: 75scottsdale on September 30, 2013, 01:47:20 am

Hey guys, I got a 75 Scottsdale with factory a/c and I was needin a little help with the HVAC vacuum hoses under the dash.

Whoever owned the truck in the past decided to cut hoses and do all other sorts of crazy stuff under the dash lol.

Im just wantin to know if someone can post some pics or a diagram of the vacuum lines under the dash, Some pics of the heater and a/c boxes would be nice to if any of you guys wouldn't mind takin a few minutes to snap a few pics, just to have a visual of what things should look like.

Im a mechanic at a farm service shop so im familiar with HVAC and how things operate I just need something to go by, thanks guys.

Title: Re: Help with HVAC?
Post by: Jason S on September 30, 2013, 07:19:19 pm

Schematics and diagrams are here: 

http://forum.73-87chevytrucks.com/smforum/index.php/topic,25639.0.html (http://forum.73-87chevytrucks.com/smforum/index.php/topic,25639.0.html)

The bulk of the information you'll need (i.e., vacuum schematics) should be in the '74 Light Truck Service manual with any additional changes in the '75 Supplement. 

As you may have already know, '73-'75  HVAC systems were different than the '76-up systems, including: the dash control panel, underdash portion of the system, electrical wiring and general operation. 

Title: Re: Help with HVAC?
Post by: 75scottsdale on October 02, 2013, 11:06:05 pm

Alright, ill try and get one of the service manuals in.
Thanks for the link and info bud.