Expansion valve for 1970 Clardy under dash

[Rweaver428]

Hello. I’m trying to resurrect the Clardy under dash AC system in my 1970 Wagoneer, Buick 350 powered, 3:31 gears. The AC did not work and I don’t know the history of it, other than it was dealer installed. I have the original installation instructions, charging instructions, and parts diagram. I have replaced the condenser with a parallel flow, new drier, and replaced the York compressor with a Sanden style 508 with oil for 134a refrigerant. I flushed the original evaporator and checked for leaks— it is good so I will reuse it. I would like to replace the original expansion valve with a new one, but I’m not sure which one to get. The original is a block style, Ranco EXV-921. I cannot find any specs on it. It is for O-ring style ends, 2 #8s, 1 #10, and 1 #6. I haven’t been able to find much info on replacing the EXV, but I did find some 70’s BMW info that used the Clardy system and people have used the Four Seasons 38878 (1.5 ton, Superheat 5) and 38901 (1.5 ton, Superheat 8). I don’t know which exv would be better— the superheat 5 or 8, or does it matter? Any info/advice is greatly appreciated. Thank you.

[JohnHere]

I have the original installation instructions, charging instructions, and parts diagram.

That's "gold." Be sure to hang onto it.

I would like to replace the original expansion valve with a new one, but I’m not sure which one to get.

Unless the original TXV is corroded or otherwise damaged, why not re-use it?

[Rweaver428]

I never really thought about reusing it. I just thought if it could replace it with something new, I wouldn’t have to worry about putting it all back together and it not working, or not working right with 134a. Does the refrigerant matter to the exv? Do they go bad? Can they be cleaned or checked? Threads look a little boogered up in one port. Attached is a pic of the valve. I will gladly scan the Clardy docs and attach them if it would help someone.

[JohnHere]

From outward appearances, your original TXV looks pretty good. Hopefully, the internal sealed and charged portion is intact as well. The refrigerant doesn't "matter" to a TXV. I believe there is sophisticated equipment that not many people have to verify a TXV's operation. Best option for a home mechanic is to clean up what you have, install it, and see if it works.

As you probably know, Clardy is long out of business. For a system that old, it's somewhat of a guess that the original TXV will work. If it were mine, I would try reusing it. Regardless, if you want to replace it, a Four Seasons #38881 is reportedly a drop-in replacement. I'm not sure of its superheat spec, though. Contact Tim at ACKits.com, this Forum's sponsor, to see whether he can get one for you.

[Tim]

I'm with John, if it is working reuse it—probably a better valve than what is made today anyway.

[JohnHere]

I will gladly scan the Clardy docs and attach them if it would help someone.

I'm curious about the original R-12 spec...I would guess about 3 pounds.

[Rweaver428]

Looks like 2 lbs., unless it’s for the trunk mount system, which is 3 lbs.

[JohnHere]

Appreciate your posting the attachment. That system originally required less R-12 than I thought. Kudos to the OEM for specifying the exact weight-of-charge in 1960.