67 AC Capillary line Positioning

[Mark P.]

I have removed and in the process of rebuilding the AC system on my 67 small block car. The capillary lines were in disarray and I have no idea as to the proper placement of the two lines that are connected to the expansion valve. Does someone have a picture that they can share or recommend a book that illustrates proper placement.

Thanks---Mark

[Mike G.]

Re: 67 AC Capillary line Positioning

I realize that you have a POA valve rather than an STV, but this photo of my '65 might help a little. The AIM drawing wasn't the best, but it's worth looking at if you haven't already done so. On mine the two capillary tubes are secured to the evaporator box with a small clamp.

[Joe R.]

Re: 67 AC Capillary line Positioning

I have removed and in the process of rebuilding the AC system on my 67 small block car. The capillary lines were in disarray and I have no idea as to the proper placement of the two lines that are connected to the expansion valve. Does someone have a picture that they can share or recommend a book that illustrates proper placement.

Thanks---Mark

Hi Mark:

I have a 67 small block with AC, and I would be happy to take some photos for you this weekend. In the meantime, the best photo I have in my archive is just of the POA valve. I posted that photo in an earlier thread, and now the TDB won't let me post it again. Hopefully you can get to it at:

https://www.forums.ncrs.org/attachment.php?attachmentid=12163&d=1213150443&uid=4489

As you try to reconstruct the factory configuration, a couple things are worth noting:

1) GM used two styles of POA valves, with the difference being where the pipe connections come out on the side. The Corvette version is shown the photo I referenced.

2) Replacement expansion valves have longer tubes and a flat temperature bulb (as opposed to the J-shaped bulb on the original). If you have a replacement expansion valve, you will not be able to exactly duplicate the original configuration. I would need a better photo of your expansion valve to figure out what you have.

[Larry M.]

Re: 67 AC Capillary line Positioning

Mark:

I also have a 1967 SB with factory air, and can help with your questions. I will check my POA connections today and report later on this evening.

POA valves are actually available in THREE different models with different connections. They are available NOS ($$$), used/reconditioned, and rebuilt. If you need assistance finding one or rebuilding, let us know.

ALMOST EXACT reproductions are now available for the expansion valve, which have the correct J-shaped end. I believe that Corvette Central is selling these....there are also other suppliers that I can list if needed. There should be a small screen in the expansion valve inlet to catch debris. These are also available for very little cost ($).

Suggest you make a list of all your questions and post it. Also check the archives under my name, as well as Joe's and Mike's. You should find many posts/answers.

Will get back to you later on capillary tubing orientation.

Larry

[Mark P.]

Re: 67 AC Capillary line Positioning

Larry, Joe and Mike

I have attached another photo illustrating the POA that I removed and the sensing end connected to the power element of the expansion valve.

I have looked in the judging manual and the 67 Chassis Service Manual and both illustrate a similar cap tube routing. It just appears to me that I have too much capillary tube length to duplicate the routing in these manuals. My fall back position will be to coil the excess tube around the power element while following the routing of the JM.

For what it is worth, the AC system was working properly when removed from service in 2005.

I will be reading your posts in the archives as I progress through my project.

Thanks----Mark

[Larry M.]

Re: 67 AC Capillary line Positioning

Mark:

Your POA valve looks to be the correct one for your car. The expansion valve is a replacement with WAY TOO MUCH capillary tubing. Suggest purchasing one of the correct looking replacements with the right capillary tubing lengths. Corvette Central (and others) sell these.

Since it came from a functioning system, I assume you know what each connection is on the POA. If not, let me know.

The capillary tube routing and the other (external equalizer) tube routing from the expansion valve are pretty much "shortest distance" to get to the correct fittings/locations.

Again, let us know other questions you may have. The 1967 Chevrolet Service Manual has a LOT of good information and diagrams on air conditioning. Get one, if you do not already have.

Larry

[Mike G.]

CC's expansion valve

Yeah, that looks like the ticket for a replacement Exp Valve. The formed bulb is a big plus. Just needs a little aluminum paint to get rid of that brass plumbing-fitting look.

[Joe R.]

Re: 67 AC Capillary line Positioning

Hi Mark:

I agree that the POA valve looks correct and the expansion valve appears to be a generic replacement.

Attached are two photos of my restored system that should give some indication about what the expansion valve looks like and how the tubes are routed. I realize that the expansion valve photo is not well illuminated, so let me know if you need more photos.

BTW, the consensus view seems to be that the original screw-on cap on the POA valve was aluminum, while the one on the compressor was brass. I think the one shown on your POA valve is brass. Long Island Corvette sells a reproduction aluminum cap.