Table 5 – Troubleshooting Guide
Problem
Possible Cause
action
General operating
problems . Humidifier
will not turn on or
turn off .
Field-wired terminal
connections .
Check L1, N/L2 and Ground connections .
Check HUMIDISTAT and FAN PACK Terminal connections .
HUMIDISTAT terminals must be connected to an on/off device . Control circuit board will be damaged
if If 24 volts are connected to HUMIDISTAT terminals .
Check wiring connections and settings on Accessory items such as high limit switch and airflow
proving switch .
Internal connections .
Check electrode and high water probe connections on the top of the canister .
Check to make sure two sets of blue/white wire jumpers from control circuit board to current sensing
circuit board are secure and have the proper polarity . Blue wire on jumper set towards front of
humidifier should be on top on both plugs . Blue wire on jumper set towards back of humidifier should
be on bottom of both plugs .
Make sure ribbon cable from membrane switch is securely plugged into control circuit board .
Check that terminals from internal components are securely attached to proper tabs on circuit boards .
Make sure one of the electrode wires extends through toroid ring on current sensing circuit board .
Make sure Black/white wire from L1 is attached to terminal that matches input voltage .
No power to humidifier .
Check main power supply and switch .
Check for proper voltage across L1 and N/L2 terminals .
Humidifier not turned on .
Make sure front cover is attached to engage safety interlock switch . Press On/Off button .
No power to 24 volt control
circuit .
Make sure ribbon cable from membrane switch is securely plugged into control circuit board .
Check reset switch on transformer .
With humidifier energized, check for 24± 6 volts AC across J2 & J5 terminals . If okay, check for 5
Volts DC 5V and GND test points on control circuit board . If okay, replace membrane switch . If
not, replace control circuit board .
If 5 volts DC are not present b5V and GND test points, remove blue/white wire jumpers and
check DC voltage 5V and GRD points . If 5 Volts DC are present, replace current sensing circuit
board . If 5 volts DC are not present, replace control circuit board .
Steam Light does not
turn on .
Call for humidity not being
received .
Check control wiring and setting .
Check wiring and settings of high RH limit switch and airflow proving switch if installed .
Water is leaking from
humidifier .
Loose plumbing
connections .
Check water supply connection at fill valve inlet . Tighten as needed .
Check internal hose clamp connections . Reposition clamps and tighten as needed .
Check steam hose connection on top of canister . Tighten clamp as needed .
Water constantly runs
down drain .
Malfunctioning drain valve . Check valve function using Test Mode .
Debris in drain valve
preventing it from closing .
Remove canister and clean debris from drain valve .
O-ring in drain valve is not
properly seated in groove .
Remove canister and reposition O-ring .
Water is flowing from fill
cup overflow port .
Check internal hoses and remove kinks or blockage .
Disassemble brass fitting in feed line between inlet valve and fill cup . Make sure small rubber flow
orifice is in place in brass fitting .
CHeCkInG SySTeM oPeRaTIon & TRoUbleSHooTInG
(ConTInUeD)
19
