chevelle 3G A/C firewall hole ID

by 76Chevelle2Tone Sun Oct 29, 2023 5:38 pm

I couldn't find any pictures of G3 chevelle factory A/C firewalls with labeled openings. The manual is no use. Are there any sources for this? Thanks

by relic7680 Wed Nov 01, 2023 11:59 pm

What information are you looking to obtain, exactly?

by 76Chevelle2Tone Thu Nov 02, 2023 12:33 am

I can't tell if there is one or two firewall openings for the A/C. Second is there a full correspondence (including pad studs) between the firewalls without A/C with the A/C firewall except for the A/C related openings? Third what are the exact grommets used in the A/C firewall?

Understand that my car has always been a daily driver so I have never done a frame off resto where these questions probably would have been answered. It's also the case that online documentation is very poor for G3 cars as opposed to earlier or even later generations. And in this case the manual is no help either.

by relic7680 Thu Nov 02, 2023 9:54 am

I've attached some pics on when the hvac was stripped off the firewall in '76 Sprint. I retrofitted the aftermarket a/c delete cover. Maybe that will help? Let me know.

chevelle 3G A/C firewall hole ID D4840010

chevelle 3G A/C firewall hole ID Img_4810

by 76Chevelle2Tone Thu Nov 02, 2023 12:23 pm

Thanks very much for your reply. I think I would need two bare firewalls - one A/C and one without - to really get a handle on this. But with respect to the first question the issue is up where the cable router is. I see two grommets on my car where wiring goes in. One is pretty much in the center of the firewall behind the carb while the second is on the passenger side at about the same height nearer the evaporator.

by relic7680 Thu Nov 02, 2023 12:41 pm

If you would like, I can get some more detailed pics of my firewall...although the setup is not 100% stock. I'm running a copper line through to an aftermarket o/p gauge and have also have some body grounds that most likely deviate from stock (car was fairly adulterated when I got it in 2004).
One thing that I will say is that you CANNOT use a OE heater only box on a factory ac car....holes in the firewall are different, hence the fiberglass aftermarket covers.

by 76Chevelle2Tone Thu Nov 02, 2023 12:45 pm

Thanks again. Yes I am very aware that the heater box is different in A/C and non A/C cars. The difference is quite obvious looking at them. Also my car is very stock apart from some minor interior customized reupholstering as it has always been a regular driver and I have done stock repair/replacement bit by bit as needed. Now is the first time I am more systematically renovating the car which is why I am having more questions. Smile

I got it about 33 years ago from the first owner who was an elderly man and he (or a mechanic) had done very little with the car other than disable the seat belt warning buzzer and put a bolt in the EGR vacuum hose.

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chevelle 3G A/C firewall hole ID

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