Troubleshooting

To isolate a malfunction, proceed as follows:

Clearly define the problem (or symptom) and when it occurs.
Locate the problem in the Troubleshooting table.
Review all possible causes. Then, one-at-a-time, work through the list of corrections until the problem is solved.

Problem	Cause	Solution
Product not holding temperature
	Control temperature set too low	Increase air temperature
	Heat settings too low	Remove front cover and adjust shelf and base heat settings
	Heat settings too low	Have heat zones set to factory default temperatures
	Door gasket damaged or worn	Replace bad door gaskets
	Bad air heater	Check heaters and replace if bad See Tech Mode items 10 and 16
	Bad air heater	Check heaters and replace if bad
	Blower not working	Check blower and replace if bad
	Blower not working	Check blower and replace if bad See Tech Mode item 18
	Bad air heater, or blower relays	Replace relay See Tech Mode items 10 and 16
	Bad high limit	Check high limit and replace if bad
	Low or improper voltage	Compare receptacle voltage to data plate voltage
	Air probe faulty, open (“E-6A”), or shorted (“E-6B”)	Check probe resistance and replace, if necessary
	Doors/drawers left open	Keep doors/drawers closed except to load and serve product
	Product held too long	Hold product only for recommended times
	Product not placed correctly in unit	Place product in unit as per operation instructions.
	Control temperature set too low	Increase air temperature (CDT control only) or Increase thermostat setting by removing hole plug on control panel and turning the shaft clockwise with a screwdriver
	Product not hot when placed in unit	Place prepackaged hot food in unit
Cabinet steaming product soggy	Humidity setpoint too high	Decrease humidity setpoint
	Water heater probe faulty, open (“E-12A”), or closed (“E-12B”)	Check probe resistance and replace, if necessary
	Bad humidity sensor (“E-17”)	Replace humidity sensor
	Relay stuck closed	Replace relay
	Vent stuck closed (“E-80”)	Bad vent motor - replace Check alignment and condition of mechanical vent parts Vent acorn nuts too tight, loosen, if necessary
	Vent not set properly (units with vent adjustment only)	Adjust vent
Product dry	Humidity set too low	Increase humidity setpoint
	No water in pan	Check water shut-off valve Adjust flow control valve Check solenoid valve and relay
	Bad float switch	Replace float switch
	Bad water heater high limit	Replace high limit
	Bad water heater	Check heater and replace if bad; see Tech Mode item 18
	Vent stuck open ("E-80")	Bad vent motor - replace Check alignment and condition of mechanical vent parts
Unit not reaching set temperature	Doors left open	Keep doors closed except to load and serve product
	Door gasket damaged or worn	Replace bad door gaskets
	Thermometer not indicating true temperature	Check cabinet temperature with another thermometer; have thermometer replaced if necessary
	Blower not working	Check Blower and replace if bad
	Blower not working	Check Blower and replace if bad; see Tech Mode item 18
	Bad air heater	Check heaters and replace if bad; see Tech Mode item 18
	Bad air heater, or blower relays	Replace relay
	Defective high limit on one of heaters	Check high limit; replace
Unit not heating	Bad high limit	Check high limit; replace if bad
	Bad control board	Replace control board
	Bad air heater or blower relays	Replace relay
	Bad air heater	Check heaters and replace if bad; see Tech Mode item 18
	Bad air heater	Check heaters and replace if bad
	Faulty wiring	Check for loose connections or broken wires
	Blown fuse	Change 15 amp fuse.
	Faulty thermostat	Check thermostat
Unit not heating	Bad control board	Check set point reading; if unit for heat below setpoint and not calling for heat, control board defective. Replace control board
	Blower not working	Check blower and replace if bad; see Tech Mode item 18
	Faulty contactor	Check contactor and replace if necessary
	Relay stuck closed	Replace relay
Unit not heating	Bad air heater	Check heaters and replace if bad
	Faulty wiring	Check for loose connections or broken wires
	Faulty solid-state relay (CDT units only)	Replace solid-state relay
	Faulty control board (CDT units only)	Replace control board
	Faulty thermostat	Check thermostat and replace if needed
Unit not heating	Control board not calling for heat	Verify set-point reading; if zone (see Zone Positions at left) tempeature is below setpoint and not calling for heat (no 5 vdc), control board defective
Water does not drain	Drain clogged	Remove drain obstruction
With switch in ON position the cabinet is completely inoperative	Unit not connected to electrical supply	Plug cord into electrical outlet
	Open breaker or fuse	Reset breaker or install new fuse in junction box
	Faulty cord or plug	Check cord and plug
	Faulty power switch	Check power switch
	In-unit resettable breakers	Press on each white resettable breaker button.
With power switch in POWER position, unit is completely inoperative (no power)	Open circuit	Check to see that unit is plugged in. Check breaker or fuse at supply box. Check control panel fuses per Replacing the Fuse and Fuse Holder. Check voltage at wall receptacle. Check POWER switch; replace if defective. Check cord and plug for loose connections.
	Control board defective	Check for 12 volt input from transformer; replace if defective
	Transformer defective	Check input and output voltage; replace if defective
Shelf won't heat	Shelf not plugged into receptacle properly	Check that the shelf plug is firmly pushed into receptacle in the interior of the unit.
	Faulty shelf heat relay	Check and replace if necessary
	Faulty shelf heater	Check and replace if necessary
	Unit not preheated	Preheat unit before loading product
	Faulty PC board	Replace PC board
	Temperature setting “OFF”	Remove front cover and increase shelf heat setting
Unit overheating	Faulty thermostat	Check thermostat; replace thermostat
	Faulty blower	Check blowers; replace blower
	Faulty control board (CDT units only)	Replace control board.
	Faulty blowers	Check blowers; replace blower
No base heat	Faulty base heat relay	Check and replace if necessary
	Faulty base heater	Check and replace if necessary
	Unit not preheated	Preheat unit before loading product
	Faulty PC board	Replace PC board
No light(s)	Faulty contactor	Check contactor and replace if necessary
	Light socket shorted	Replace light socket
	Faulty fluorescent light bulb	Replace fluourescent light bulb
	Faulty lamp ballast	Replace ballast
With power switch turned on, the blower and fan operate, but the power light is off and the unit won’t heat	Open high limit	With unit cool, check high limit If the high limit opened because of overheating, refer to Unit Overheats section of Troubleshooting Guide
Red LED, when should be green, or vice versa	Polarity reversed on LED wires	Access the LED wires on side of unit and reverse wires at wire nuts
Front LED does not light	Faulty LED	Access LED wires on side of unit and check for dc voltage; if no voltage, check for voltage at control board; if voltage present, replace LED
Individual zone does not heat	Faulty heat relay	Testing for proper relay operation: To avoid electrical shock, make connections before applying power, take reading, and remove power before removing meter leads. The following checks are performed with the wall circuit breaker closed and the main power switch in the ON position. With no power (5 vdc) going to the relay, 120 volts should show on the output side of the relay, and 0 volts on the input (5 volts). If no 120 volts, check for open heater, and if heater is OK, replace relay. With the component energized, 0 volts should show on the output side of the relay, and 5 vdc on the input side. If not, replace relay. Also, check for reverse polarity of 5 vdc to relay-reference wiring diagram. If voltage varies from steps 1 and 2, remove power to unit pull input wires from relay and place leads of meter onto input wires. Reapply power to unit. When unit is running, if the input wires to relay shows 5vdc, the relay is faulty.
	Faulty heater	Refer to wiring diagrams and with the outputs on, check across terminal #1 of the appropriate relay and the neutral wire (#N5 on 554 or #N2 on 1L or 22) at the transformer. If meter shows full voltage (120V), but heater is not heating, replace heater and liner assy. Refer to wiring diagrams and disconnect 15-pin connector at control board. With an ohm meter, check between the appropriate terminals on connector and the corresponding terminal on the terminal block. Meter should read 35 to 41 ohms at room temperature. Replace liner and heater assy if necessary
	Faulty heater RTD	Refer to wiring diagram and disconnect 15-pin connector at control board. With an ohm meter, check between the appropriate terminals on connector, based upon which RTD is being checked. Meter should read about 1080 ohms at room temperature. Replace liner and heater assy. if necessary.

Reference

Specifications

Error Codes

HHC 99X Wiring Diagrams