AC install after 460 swap

[Littlebeefy]

Hoping this thread can help people looking to modernize their stock A/C system a bit.

I pulled the original hoses and manifolds from my 351W compressor. Here's the pics:




The docs Gary loaded are incredibly useful and pretty clearly describes operation, service, troubleshooting, etc.

One thing that I couldn't find mention of is the compressor relief valve. In the stock configuration, you can see the relief valve sticking out of the back of the high side manifold. My understanding of the function of this device is that it is a "last fail-safe" for your A/C system; when your clutch fails to de-energize, the increasing pressure will eventually force this valve open and vent the refrigerant to keep the system from bursting. So in a normal and functioning A/C, this valve serves no purpose.

Without a stock manifold, I don't have anywhere to put this valve. Like anything, I'm sure I could find a way to fabricate something if absolutely necessary. Is it necessary? Is there an alternative to a mechanical valve as a fail-safe? Is there a simple way to add this valve to an in-line fitting or T-adapter? Basically, for anyone who isn't using the stock A/C manifold in your truck, how are you integrating the compressor relief valve?

Second question, these hoses have a bunch of service ports and I don't understand why. I don't know if this is necessary or just the old way that they did things. How many service ports do I actually need if I'm running R134? Can they just be #6 schrader valves? My understanding was that I just need one on the high side and one on the low side. Is that true? Does it matter where on each side they are?

I know this thread is about non-stock configurations, but I imagine lots of people have swapped their compressor styles and had to deal with the incompatible manifolds. If so, or if you happen to know about A/C, I'd appreciate your advice here.

[85lebaront2]

Chad, you are running into what I did on my Chrysler, in the change to factory R134 systems, the lines and compressors changed. Go look at a site called Vintage Air, they make kits for all sort of vehicles. If you have an Automotive AC shop they may have a source for a connection block.

The issue is the change from the FS-6 to FS-10 compressors, FS-6 has the ports in the middle of the compressor body with two connection blocks. The FS-10 has the connections on the rear head of the compressor.

The valves at the compressor end of your hoses can be eliminated if necessary in order to connect the lines, they are service valves that were pretty much eliminated on later models.

[Pete Whitstone]

Littlebeefy wrote

Second question, these hoses have a bunch of service ports and I don't understand why. I don't know if this is necessary or just the old way that they did things. How many service ports do I actually need if I'm running R134? Can they just be #6 schrader valves? My understanding was that I just need one on the high side and one on the low side. Is that true? Does it matter where on each side they are?

I'm pretty sure there are different valves for the high side and the low side, so the AC equipment can't be hooked up wrong. And yes, I'm pretty sure that you only need a high side and a low side, and placement does not matter. Physics dictates that the pressure will be the same anywhere in the high side and anywhere in the low side, so I can't see why it would matter.

[FuzzFace2]

What you are seeing are not "service ports" but "service valves".
Pull the caps off and you will see square shafts for the valves.

You had factory AC the the valves were used to close off the system from the compressor so you would not lose any charge other than in the compressor when  you needed to change it out.
My 81 F100 has the same valves but I have never used them.

IIRC there is a high side service port on the hose by the compressor.
The low side service port is over by the evap coil & dryer.
Dave ----