Firewall Difference Between AC and Non AC for 1968

Q: Firewall Difference Between AC and Non AC for 1968

I’ve been working on my 1968 Firebird. The car originally had AC, but most of the components were not reinstalled when someone swapped the 6cyl for a V8. I’m not concerned with the car being original so I’m not going to try to put AC back on it. The heater blower motor case for my car also housed the evaporator core (I think that is what it is called). I was hoping to use the much smaller heater blower motor case off of a non-AC car, but according to the Ames catalog it “won’t work on any car which was originally equipped with AC”. Can someone tell me what is different about the firewall between cars with and w/o AC…. or can I make the non-AC case fit on my car?

A: The holes in the firewall are different for A/C cars. The hole for the A/C is about 6″ wide and 11″ tall. The heater only firewall is about 14″ long and 5″ tall (all dimensions are very approximate). Narrow tall vs short long… so to speak.

I had a 1969 400 that someone removed the A/C box and replaced it with a standard heater. He simply took a piece of sheet metal and covered the original hole (using silicone and pop rivets and cut a new hole the shape he needed. The heater cover will bolt right up after drilling a couple of new mounting holes. He painted the firewall all the same color and overall, it didn’t look too bad.

If you decide you want to do this and need the heater box and controls (different on non-A/C cars) let me know. I got a couple I’ll let go CHEAP.

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