Sensor troubleshooting guide – Haws VRKHO1 User Manual

Page 3

10/09

Model VRKHO1

Page 3 of 4

SENSOR TROUBLESHOOTING GUIDE

Step 1: A loud click indicates when the solenoid valve is turned on. If valve clicks, but no water

comes on make sure screwdriver stop is wide open (turn counterclockwise). If valve clicks
but still no water, check valve or line for obstruction. If valve does not click when hand is
placed a few inches in front of sensor, go on to next step. DO NOT ATTEMPT TO
DISASSEMBLE SENSOR, DAMAGE WILL RESULT.

Step 2: Using volt meter, check for 24VAC across the transformer terminals. Replace transformer if

faulty.

Step 3: Check solenoid valve. Voltage rating on valve top plate should be 24VAC. Unplug sensor

from wiring harness. Using a volt meter, check for 24VAC signal from wiring harness (use
hand in front of sensor to activate).

Valve coil may be checked for continuity using an Ohm meter. Disconnect valve from wiring
harness and sensor wires. Connect each valve lead to a meter lead. One meter lead should
be plugged into meter ground socket and one should be plugged into socket marked “Ohm”.
Coil resistance should be around 10 – 20 Ohms. If resistance is near infinity or zero, solenoid
coil is at fault. Coils may be easily replaced without disconnecting valve body from plumbing.
Replace with new 24VAC rated coil.

Step 4: Check wiring harness. If wiring harness appears to be hooked up correctly, disconnect

harness from valve, sensor and power cord, then check harness for continuity using Ohm
meter. Resistance between connectors attached to each other by wires should be near zero
Ohms. High resistance indicates a faulty connector or wire. There should be infinite
resistance between separate (independent) legs of the wiring harness. Less than infinite
resistance indicates a short or cross connection. If wiring harness has proper continuity and
is hooked up properly, proceed to Step 5.

Step 5: Check sensor. If Steps 2, 3 and 4 all check out OK, the sensor is probably the problem. The

sensor acts pretty much like a simple relay or switch. The SCR (semiconductor relay) within
the sensor will not fully switch without a 6 to 11 Watt load such as a solenoid valve or
household light bulb. For this reason, a simple Ohm meter test on a good sensor which is not
connected to the proper load will yield misleading results seemingly indicating improper
function.

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