#1  
Old 10-13-2022, 06:16 PM
1980 TA 1980 TA is offline
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Join Date: Jun 2004
Location: Rolla, MO
Posts: 353
Default 71 LeMans HVAC controls

Working on getting the HVAC working on my 71 LeMans. It is a factory AC car and the previous owner put on an AC delete box. I have the blower working and vacuum to the back of the controls and they blow air where you want them.

I was a little confused on how exactly the settings for the AC were supposed to work.

Left to right it says Inside, AC, Bi Level, Heat and then Defrost.

I would assume that inside blocks of the fresh air vent, and the rest of the settings have the outside vent open and mixing fresh air.

If that is correct, what does the two position switch marked Norm and Vent do?

On a crisp night, I don't seem to find any setting that lets in cold outside air.

I've removed the glove box and confirmed that the temp cable moves from full cold to hot.

Trying to figure out how GM intended it to work originally.

  #2  
Old 10-13-2022, 08:28 PM
gto4ben gto4ben is offline
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Join Date: Aug 2006
Location: Los Angeles, CA
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Owners Manual should explain the control functions adequately. Here's a 1969 excerpt which is the same. AC compressor is ON except when you set the Norm-Vent Lever to Vent.
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  #3  
Old 10-13-2022, 09:51 PM
1980 TA 1980 TA is offline
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Join Date: Jun 2004
Location: Rolla, MO
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That's exactly what I needed. Thanks a lot. Everything seems to be working as it should.

I need to get the evap case back on and add a compressor and condenser coil and I should be up and running. Thankfully the previous owner saved the evap case. I have a set of brackets left over and will be adding a pro6ten compressor. Be a good time to add a more modern condenser. Should be a good winter project.

  #4  
Old 10-15-2022, 01:16 PM
tjs72lemans tjs72lemans is offline
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Join Date: Oct 2017
Location: Winona, MN
Posts: 1,157
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You'll find that most of the top functions automatically switch the Normal/Vent switch to Normal. If you had it on Vent and switched the Off lever to AC, the Vent lever automatically flips to Normal. I think Heat is the only top function where in CAN run in Vent mode. I just went through this this summer. Test it. Mine is a 72 Lemans with factory AC.
I see now that I go back and read that second page below, it explains what I said.


Last edited by tjs72lemans; 10-15-2022 at 01:23 PM.
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