Quito

I am interested in learning the procedure on replacing the A/C evaporator on a 1977 Corvette. I have a Chilton and Haynes repair manuals but they do not cover this work in detail.

Please advise where to get the procedure or provide the basic steps necessary to complete this work.

Thanks - Quito

markids77

Have an A/C shop evacuate whatever freon is in the system now; it is illegal to vent refrigerant to the atmosphere. Remove the hard line from the accumulator/dryer and the flex line from same. Remove the dryer from the car. The A/C housing is a"clamshell" design bolted together with the screws being on the fender side of the housing where they are nearly impossible to reach unless the engine is out of the car. There is also one stud which will need to come loose on the firewall. Pry the two halves of the clamshell apart, insert new evap core and reverse disassembly... but get a new accumulator/dryer a while you are shopping parts. Be certain your evap comes with a new orifice tube or get one of those as well, and new o-rings for each tube joint. Lube each o-ring with refrigerant oil on install so they seat correctly. Decide whether you'll recharge with R-12 or R-134 and use a suitable oil for that. Bring the car back to the A/C shop for system vacuum, leak check and recharge. Try your best not to look at anything else under the hood to avoid "while I'm at it" disease which could lead to the entire car being scattered all over your garage for the next several years!

Rotonda

Before you begin to buy parts, confirm whether your 77 has a VIR system or the later orifice tube system. The change from VIR to orifice happened in mid-year.

markids77

Quick check... look at your compressor. If it's about a foot long, cylindrical and 6 or so inches in diameter it's a Frigidaire with VIR. If it's about 9 inches long, 12 inches or so in diameter it's a Harrison and uses a dryer. My car has the late Harrison compressor so I used it as an example. Changing the actual evap core should be similar with both systems... if you have the early style search "VIR eliminator kit" to do instead of a new accumulator/dtyer.

noonie

I'll just add that you must remove the coolant recovery tank to slip everything out.
It really looks worse than it is.