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Evaporator case modification on 64 Corvette

Posted: Wed Apr 17, 2019 5:21 pm
by vitaminmopar
I am new to the forum and AC in general. I am hoping someone with design experience can tell me if my idea is worth pursuing. Sorry for the length of the post.

I have a 64 Corvette (C2) with factory air. I am restoring the AC system and one area I would like to improve on is the air flow into the cabin. I am considering modifying the evaporator case in two areas to accomplish this. When new the air flow through this system was never great.

First, the original C2 evaporator inlet opening is small, measures 3 x 3 1/4. The air flow has to make a 90 degree turn before flowing across the evaporator. I have a 1984 Corvette (C4) evaporator case which has a larger blower cage and evaporator inlet measures 3 ¾ x 4. The inlet area is about 33% larger plus it has a transitional expanding opening. I will have to cut the C2 inlet side opening to accept the larger C4 blower mount section and graft in using fiberglass. Regardless of year, either motor is in a 30 amp circuit. Question: Will I increase air flow? I have linked a photo album to help show my proposed idea. All but the last two photos pertain to this idea.

Second the evap coil is angled downward in the case maybe 15 degrees. I do not know why this was done but I suspect it was for condensate to be blown downward to the drain. I can’t change the angle but thought I could add an ABS sheet to the case wall at a complementary angle to form a transition. I think I would need to leave a 1/4 - 3/8 inch gap at the bottom and top of the ABS. I’m thinking the top would need a lip to stop condensate from being blown into the ducting. Condensate would be arrested at the top gap by the lip and forced down the evaporator case wall towards the drain. Question: Will I increase flow and stop condensate from entering the ducting? Reference the last two photos in the link above.

Any ideas about what I am proposing?