Dangerous compressor! What part needs to be replaced?

[Lugnutz65]

Hello!
I think my compressor needs a switch or valve replaced. Please help if you can so I don't waste money or make a dangerous repair that is incorrect.

I have a new to me (used) Ingersoll Rand T30 compressor. Kohler gas engine and a 2 stage pump on top of a 30 gallon tank. It has some age to it but it makes good air pressure.

The pressure builds to 175psi at which point a switch is supposed to divert air away from the tank and out a bleeder valve. That way the tank will not continue to build pressure above 175psi.

Well, the switch does not work properly. I think it is the switch I have labeled "PART B" in the photos. It has a toggle piece at the top so that you can manually activate the switch. Under normal operation, the toggle is DOWN and the switch operates automatically.

Here's what I think happens, but I really don't know. So I'm asking the experts here. When the switch works properly, at 175psi, it allows air to flow through a thin tube which activates a piston switch to move an engine kickdown lever which slows the engine RPMs. At the same time, air is diverted away from the tank and out through a bleeder. This is all supposed to happen AUTOMATICALLY when the toggle is in the down position.

As pressure in the tank drops from use, the switch closes the bleeder and builds air up in the tank again. The engine RPMs kick up so the pump makes air faster. The cycle continues as long as the compressor is "ON".

Right now, the tanks pressure builds above 175psi and the switch does not activate. If I tickle the switch when pressure is above 175psi, it usually activates. I got 200psi last night and the safety valve blew off pressure. That's NOT supposed to happen! Yikes!

Please see the pictures below for additional info.