Overview
Primary vacuum solenoid valve — three-way, normally closed, Viton seal, 12 V DC. HydraMaster part number 000-169-070, listed as Valve, Primary Vac. Solenoid. Commonly called the MAC solenoid after its manufacturer.
It is a pneumatic control valve, not a water valve. It switches the vacuum or air signal that operates the machine's air cylinders — which is why a fault here shows up as something mechanical refusing to move rather than as a leak.
What it fits and how many
CCW's record lists it for the Boxxer 421, Boxxer 427, MAXX 450D, MAXX 470D, MAXX 550, all CDS units and the Bridgepoint Javelin. HydraMaster's suggested spares schedule lists it against the Boxxer 421, Boxxer 427, CDS 4.6 / 4.8, CTS330 and MAXX 450D / 470D.
Named in the machine parts lists as:
- Boxxer 421 — 2 fitted, upper and lower primary vacuum solenoid valves
- Boxxer 427 — 2 fitted
- MAXX 450D / 470D — 2 fitted, upper and lower
Most machines carry two — an upper and a lower. They do the same hours and switch the same number of times. If one has failed, budget for the other.
Specifications
- Function: 3-way, normally closed
- Seal material: Viton
- Coil: 12 V DC
Related parts
CCW's record notes two parts that go with it:
- 106-014 — vent plug
- BR002 — barb, 1/8" × 1/8" MPT brass
The solenoid works with 3/16 inch plastic vacuum line and plastic vacuum tees, and feeds the air cylinder valve (169-169) on most machines.
Diagnosing it
A failed vacuum solenoid presents as an air cylinder that will not move, moves slowly, or will not stay where it was put. Before replacing the valve, work through this order:
- Is the coil getting 12 V? A solenoid with no supply is a wiring fault, not a valve fault.
- Is the vacuum signal reaching it? The 3/16 inch plastic line perishes, splits at the barbs and gets crushed. It is the most common cause by a wide margin.
- Is the vent plug clear? A blocked vent stops a three-way valve exhausting, so the cylinder will not return.
- Does it click when energised? A click with no result points at the valve itself; no click points at the coil or the supply.
Check the diode in the circuit as well — 135-051 is there to absorb the spike this coil produces on switch-off, and a failed diode causes odd behaviour elsewhere.
Frequently asked questions
How many does my machine have?
Two on the Boxxer 421, Boxxer 427 and MAXX 450D/470D — an upper and a lower. Check yours.
Is it a water valve?
No. It switches the vacuum signal that operates the air cylinders.
Does it come with the vent plug and barb?
Those are separate part numbers — 106-014 and BR002. Ask us if you need them.
My cylinder will not move. Is it the solenoid?
Check supply voltage and the 3/16 inch vacuum line first. Both are more common than a failed valve, and both are cheaper.
Air cylinder misbehaving? Tell us the machine and what you are seeing and we will help you work through it before you order.
