Metro С5 8 Series Controlled Temperature Heated Holding Cabinets - Manual (Page 12)

10
BASIC TROUBLESHOOTING
Warning: Only factory approved service agents should attempt
to service, repair or replace electrical components,
wiring or power cord.
1. Controls do not work (no display or indicator light):
a. Check that the cabinet is plugged in.
b. Check that the outlet has power.
c. Check that the power switch is in the “On” position.
d. Check the cabinet wiring from the power cord to the power switch and to the controller.
e. Check that the fuse on the back of the controller is not blown.
f. Controller is faulty.
2. Controller temperature display does not change (displays a constant value approximately equal to the
minimum or maximum of the temperature control range, 70°F (21°C) or 200°F (93°C):
a. The temperature sensor and controller are not communicating:
i. Temperature sensor wires are broken or disconnected from the controller.
ii. Controller needs to be replaced.
iii. Temperature sensor needs to be replaced.
3. Temperature too hot:
a. Set point is too high. Turn temperature set point down to the desired temperature.
b. During initial pre-heat some over temperature may occur but will quickly return to the set point.
c. If displayed temperature exceeds 220°F (104°C):
i. Blower wiring is faulty or disconnected.
ii. Blower needs replacing.
iii. The thermostat may have failed and the thermal overload device is controlling the temperature. Stop using
the cabinet immediately and contact a factory approved service agent.
4. Temperature too low:
a. The cabinet may still be in pre-heat or recovering from a door being opened.
b. Set point is too low. Turn temperature set point up to the desired temperature.
c. A door is not closed or sealing properly.
d. Blower is not circulating air:
i. Blower wiring is faulty or disconnected.
ii. Blower needs replacing.
5. No heat generated
a. If the heat indicator light is on but the cabinet does not draw approximately 16 amps for 120V 2000W units;
12 amps for 120V 1440W units; or 8 or 9 amps for 220-240V units:
i. Air heater element may be faulty.
ii. The wiring to the air heater element may be faulty or disconnected.
iii. The controller (air heater relay) may be faulty.
b. If the heat indicator light does not come on, the controller may be faulty.
6. Displays blink “LO” and Alarm beeps (if “Sound” is on):
a. If the temperature display alternately blinks the current cabinet temperature and then “LO”, refer to steps 4 and 5.
7. Cabinet trips GFCI (ground fault circuit interrupter):
A GFCI receptacle protects against “ground faults” whenever an electrical product is plugged into the GFCI
outlet by constantly monitoring the electricity for any loss of current. If the current fl owing out of the receptacle
differs by a small amount from that returning, the GFCI quickly switches off power to that circuit. The GFCI
interrupts power extremely fast to minimize the possibility of an electric shock.
a. The heater element may absorb some moisture into its casing and insulation during shipment or during long
periods of not being used (such as during the summer in a closed school kitchen). Plug the cabinet (without
water in the water pan) into a non-GFCI outlet, set the temperature to 200°F (93°C) and let it run for 30-60
minutes to dry out any moisture the element may have absorbed. (If it trips the standard circuit breaker call
factory approved service agent.) After drying the element, plug the cabinet into the GFCI outlet; the cabinet
should run without tripping the GFCI.
b. If the cabinet still trips the GFCI, call a factory approved service agent.
Note: The temperature control does not require fi eld calibration.