I need definitive heater valve and AC expansion valve answers

[PurAU]

1969 Mustang with factory AC. Early build: (10/1/1968).

With AC to MAX, and TEMP to COLD, I have -11 vacuum to water heater valve. Is valve supposed to be OPEN or CLOSED when AC is on?
Also, without removing, AC evaporator expansion valve is straight and appears to have flanged ends.

Old Air Products, CJ Pony Parts and NPD are in conflict whit what heater and expansion valves I need to buy for replacements.

Compressor/Clutch, condenser, dryer are ALL new. Running R134A. Lowest AC vent temp I can get is 65 degrees.

Please, someone clarify what valves I need to buy.
Thanks

 

[manicmechanic007]

You need to do some diagnosis to determine that
Do you have a 1969 Body service manual with all the diag info?

 

[manicmechanic007]

Last I heard, you couldn't easily get any of that stuff for the Lincolns and T birds
We used to switch them to A/C in the summer and back to heat in the winter

 

[Mcmahst]

The heater hose valve should be closed when you engage the AC function. Those valves are available from multiple sources; my favorite is NPD. If you’ve replaced all of those parts, pulled a vacuum long enough to remove all of the moisture in the system and to verify you have no leaks, and then filled the system with the bright amount of refrigeration, then you have a complete system. Usually, expansion valves do not need to be replaced; they don’t wear.

Now, an R134 system has a lower efficiency rating than an R12 system. Most 134 systems require a much larger condensor in order to gain back some of that loss. But most cars cannot accommodate that. So, to achieve the best results, you have to eliminate that big heat source in the plenum. If you’re not sure on what heater valve you need, call the guys at NPD and they’ll help you.

Good luck.

 

[GypsyR]

Rule of thumb when running R134 in a system designed for R12 (sounds like what you are doing) is that it can and will cool but won't ever get cold. Not as built. I tried it on a few vehicles back when R134a was a lot cheaper. No bueno. That's what I got, cool, but never cold.
To get R134 cooling well you need to do at least two things. Upgrade the compressor to a Sanden to achieve the pressures you need. Kind of mandatory. Then to help it you'd want to get a dual pass upgraded condenser. NPD sells a good and fairly priced one that should be a bolt-in for you.

You can also tweak other things. And be aware that R134 tends to leak out of R12 hoses. The older rubber doesn't hold R134 well. This a very slow thing though. You might not need to top up your R134 once or maybe twice a year to compensate. Or that's what I've experienced.

Latest wheeze on Youtube is to skip all that R134 modification and just use HFC-152A , AKA computer duster, instead of R12. I've been looking into it some but haven't tried it yet.