Troubleshooting - Vulcan-Hart MHB24G Service Manual

WARNING: CERTAIN PROCEDURES IN THIS SECTION REQUIRE ELECTRICAL TESTS OR
MEASUREMENTS WHILE POWER IS APPLIED TO THE MACHINE. EXERCISE EXTREME CAUTION AT ALL
TIMES. IF TEST POINTS ARE NOT EASILY ACCESSIBLE, DISCONNECT POWER, ATTACH TEST
EQUIPMENT AND REAPPLY POWER TO TEST.
Models with new style controls: Before performing any of the troubleshooting checks listed below, remove the
cover from the main control box and check the condition of the LED'S on the relay board for the status of the
condition or component in the operating sequence. By utilizing the troubleshooting LED'S, the Service
Technician can quickly and easily determine if a component is functioning properly or in need of repair. Refer to
"RELAY BOARD" under "ELECTRICAL OPERATION".
SYMPTOM
Steamer does not operate.
Steamer ON, cannot reset low water
condition.
Steamer ON, cannot reset high pressure
condition.
Steamer ON, reset switch pressed but
blower does not operate when calling for
heat.
(boiler pressure within operating limits)
VHX SERIES STEAMER - TROUBLESHOOTING

TROUBLESHOOTING

BOILER BASE CONTROLS
1. No power to steamer.
2. F1 Fuse open.
3. Malfunctioning power switch.
4. Malfunctioning power switch latching relay (old style controls
only).
1. Low water level in boiler.
A. Water inlet valve(s) OFF.
B. Fill solenoid not receiving power, clogged or
malfunctioning.
2. Manual blowdown valve on water level probe housing open.
3. Improper ground.
4. Lime scale build-up auxiliary water level probe.
5. Malfunctioning reset switch.
6. Malfunctioning auxiliary water level control board.
1. Excessive pressure in boiler.
2. Malfunctioning reset switch.
3. Malfunctioning high pressure limit switch.
4. Malfunctioning pressure switch latching relay (old style controls
only).
1. Blower malfunctioning or loose connection on blower cord.
2. 24 VAC transformer malfunctioning.
3. Malfunction in cycling pressure switch.
4. Malfunctioning "Low Water" or "Hi Pressure" light not indicating
true condition.
5. Blower relay malfunctioning (old style controls only).
Page 61 of 68
POSSIBLE CAUSES
F24700 (October 2001)