Automotive Air Conditioning Information Forum

Hello,
We have a 86 S10 with an LS Swap that will utilize a Sanden SD7 style compressor.

What has been replaced in the truck with new:
1) Condenser
2) Evap Core
3) Dryer w/ new cycle switch, adapt service port to accept R134a style port(?)

This will be a manual "Request" style setup (like 03-07? Express Van) using a high pressure cutoff switch. PCM setup (regarding A/C)...

From what I can gather the Express van had its high pressure cutoff switch located on the compressor.
1) Is it safe to say the high pressure cutoff switch AND discharge port should be located on the discharge hose coming out of compressor?
2) What switch is best? I assume its the NC variety. Santech MT0973 (430PSI Open / 200PSI Close) or MT1635 (355PSI Open / 205 PSI Close). Is there a better switch?

Not sure yet on the orifice tube. Right now I have a new replacement (AC Delco 15-5754) for what was in there.

We live in Arizona if that helps...
Thanks,
Bill

1) yes HPCO switch on the discharge hose, you want the high side service port on the liquid line, before the orifice tube
2) I'd go for the 430 psig, 335 is way too low

Thanks for the quick response!

So, I have an "R12" high side service port between condenser and orifice tube on the stock pipe I planned on reusing. So, I'll put the adapter port on that... and the cutoff switch on the discharge hose. I bought some R12 / R134a adapters (w/ 7/16-20 threads). They do not fit high or low side. Thinking I need the 3/16" adapter to 16mm port for the high side. Any thoughts on the thread size (on the dryer) for the low side? 1/2" ACME?

Thanks Again!
Bill

If I understand the issue correctly, the R-12 service port on the original high-side line is a 1/4" flare fitting. If the new accumulator (dryer) is of the original configuration (for R-12), the threads on it are also 1/4" flare, not 1/2" ACME. So the R-134a conversion fittings should be compatible with 1/4" flare threads.

Doh! Helps if you remove the shrader valve before installing the adapter! Well, Low side is 1/4" flared and the adapter I bought (description below) fits fine. The high pressure service port, however, is smaller than 1/4" and is not flared. Thoughts?

Here is a quote of the adapters fitting I bought:

"These Low/High side retrofits/adapters/fittings will convert your old 1/4’’ SAE or 7/16"-20 UNF R12 R22 charging port and make it accept the R134a quick disconnect hose. Low Side, 1/4’’(7/16’’- 20) x 13 mm (Blue). High Side, 1/4’’(7/16’’- 20) x 16 mm (Red)."

Thanks,
Bill

Bill Reid wrote: ↑Sun Aug 07, 2022 6:23 am Doh! Helps if you remove the shrader valve before installing the adapter! Well, Low side is 1/4" flared and the adapter I bought (description below) fits fine. The high pressure service port, however, is smaller than 1/4" and is not flared. Thoughts?

Both 1/4" Flare adapters (the same thread size as 7/16"x20) should fit unless the 1/4" Flare fitting is missing from your HP line. In that case, what you're probably seeing are 1/8" NPT (National Pipe Threads), either female or male. The missing 1/4" Flare fitting should look something like this:
https://www.centurytool.net/AD24_CPS_1_ ... psad24.htm

Bill Reid wrote: ↑Sun Aug 07, 2022 6:23 am Here is a quote of the adapters fitting I bought:
"These Low/High side retrofits/adapters/fittings will convert your old 1/4’’ SAE or 7/16"-20 UNF R12 R22 charging port and make it accept the R134a quick disconnect hose. Low Side, 1/4’’(7/16’’- 20) x 13 mm (Blue). High Side, 1/4’’(7/16’’- 20) x 16 mm (Red)."

Right. The 1/4" SAE—also called 1/4" SAE Flare—has the same threads as 7/16"x20 UNF. The HS adapter should fit on the existing HS line fitting unless the fitting is missing, as mentioned above. The 13mm (Blue) and 16mm (Red) specs refer to the plastic cap sizes (inside diameter, I think).

Nothing is missing on the HP side. In fact it has a plastic screw on cap. It is definitely not 1/8" NPT male. It is not flared, has threads smaller than 1/4" SAE (7/16X20UNF), and also has a shrader valve.

That looks to be a 3/16 male flare.
This adapter to 1/4 male flare should work

https://www.centurytool.net/AD36_CPS_3_ ... psad36.htm

It is not flare... at least how I understand flare. Unless the bore is flared? Is that what you are referring to? Happy to take more pics. The top of the fitting is flat. I have a 3/16" to 16mm R134a adapter on order. When I get it I'll share. I gather this is a unique setup(?).

Are you suggesting a 2(?) adapter solution?

I appreciate everybody's time looking at this.

Thanks,
Bill

That's nothing like any R-12 test port I've ever seen. It looks like a miniature 1/2" ACME. Was a pressure switch originally screwed onto that fitting perhaps?