Compressor pressure relief valve

[HDN]

As I get parts to put one on my A3's compressor, I was wondering: Did the A2 trucks have them as well?

 

[davidb56]

Mine is on the inlet of the receiver tank. Its not near the compressor. you have to crawl under the truck by the spare to see it.

 

[HDN]

Is that the same valve as what's supposed to be on the compressor? The A3 is supposed to have one at the tanks too, but I'm not sure it's the same part number as the one to put on the compressor.

 

[Floridianson]

Are you talking about the compressor control? Cats motors had them mounted on the compressor and A2 were on the firewall if I remember.

 

[HDN]

Are you talking about the compressor control? Cats motors had them mounted on the compressor and A2 were on the firewall if I remember.

Nope, I'm talking about a safety relief valve. The A3s had a MWO for installing a tee at the compressor outlet with one side of the tee getting a relief valve. I imagine this was done to add redundancy to the existing air safety relief valve mounted to the tanks under the truck. Maybe it could get corroded from road spray and malfunction?

I'm in the process of getting parts, but I haven't found a part number yet for the valve or the tee.

 

[davidb56]

Nope, I'm talking about a safety relief valve. The A3s had a MWO for installing a tee at the compressor outlet with one side of the tee getting a relief valve. I imagine this was done to add redundancy to the existing air safety relief valve mounted to the tanks under the truck. Maybe it could get corroded from road spray and malfunction?

I'm in the process of getting parts, but I haven't found a part number yet for the valve or the tee.

when Im under the truck, I pull the relief valve "ring" occasionally to make sure the seat isn't stuck. As far as a compressor check valve, My AD9 air drier I installed has one built into it. I have no clue why the A3 has two relief valves.

 

[HDN]

After some digging, I found a web version of the MWO in question here: http://trucks25ton.tpub.com/MWO-9-2320-386-20-1/index.htm

So the stated purpose is to add a backup safety valve. Is this redundancy a thing on modern trucks?

Also, part numbers are included. I haven't dug deep yet to find them, though. The valve is cylindrical with no visible D ring, so how does one test it?