Hello and welcome to Arzel Zoning, where today we’re going to show you how to diagnose our solenoids. In a previous video, we tested the pump, so we know the pump in this panel is working correctly. Now we need to determine whether there is an issue with the solenoids.

To test the solenoid system, you will need a digital voltmeter, a digital manometer, and a pair of needle-nose pliers. A small screwdriver may also be helpful.

The first step in testing solenoids and pumps is to jumper all fan calls or set thermostats so the fan is running continuously while heating and cooling calls are off. This puts all zone solenoids into vacuum so they can be properly evaluated.

With fan operation established, the panel is powered on and the pump is running. The next step is to verify solenoid electrical connections using a digital voltmeter set to DC voltage.

Measurements are taken between the common plus terminal and each zone terminal (Zone 1, Zone 2, Zone 3). Each active zone should be checked for proper voltage. An unused zone can be used as a reference to confirm the meter is functioning correctly, typically showing around 24V DC.

Once electrical integrity is confirmed, vacuum readings are tested using a manometer. If available, red caps are used to isolate dampers from the system. The manometer is connected directly to each solenoid port.

Expected vacuum readings should be close to pump performance, typically around 60 inches of water column based on prior pump testing.

In this case, readings are significantly lower (around 0.9 to 2.7 inches), indicating a major pressure loss somewhere in the system.

The ModuPASS port is then checked as a reference point. Since it is a constant pressure port, it should show expected pressure levels if the system is healthy. However, readings remain low, confirming a leak or failure within the system.

To isolate the issue, technicians identify the vacuum (black and blue striped line) and pressure line (black and yellow striped line). Since all solenoids should be under vacuum, the pressure line is pinched to observe system response.

Each zone is then isolated individually by pinching lines one at a time. No change in pressure is observed for Zones 1 and 3, but when Zone 2 is pinched, pressure immediately rises to approximately 63 inches of water column.

This confirms that Zone 2 solenoid is leaking and is the source of the system failure.

This completes the diagnostic process for Arzel solenoids using a manometer, voltmeter, and basic hand tools.