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Refrigerators Diagnostic Procedures

5.2 Error-Based Diagnostics

The thermostat assembly has two LED indicator

lights. The green light is used to indicate that the

system is receiving voltage. The red light will ﬂash (for

approximately one quarter of a second) to indicate any

operational errors that are identiﬁed.

Refer to the following table to diagnose system errors

based on the ﬂash sequences from this indicator light.

The CD 30 series refrigerators do not include

an LED thermostat assembly, so the following

information does not apply.

Flashes Fault Description Possible Cause Recommended Action Page

1 Low Voltage Cutoﬀ

The control module experiences

voltage at or below 11.7 VDC

upon compressor startup, or

the voltage has dropped to

10.4 VDC or below aer the

compressor is running.

Monitor the voltage at the input of the control

module to ensure that there is not a voltage drop

below 0.2 VDC when the compressor attempts to

start. If the voltage drop is greater than 0.2 VDC:

• Inspect the truck wiring and all connections for

loose or corrosive terminals.

• Check for a weak cell in the truck battery.

Too Many Start

Attempts

The compressor attempts too

many starts within one minute.

• Allow the refrigerator to sit with the thermostat

set to the coldest setting, with power applied,

for two minutes to clear the fault.

• If the fault continues, complete the actions

described for the fan overload current fault.

N/A

Fan Overload

Current

The fan draws more than 0.5

amps.

• Locate and remove the wire from terminal

“F”on the control module (negative terminal

for the fan circuit).

• Attempt to restart refrigerator.

• If the fault continues, replace the control

module. If not, replace the condenser fan.

13/17

3 Motor Start Error

The rotor is jammed.

• Turn the unit oﬀ for ﬁeen minutes, and then

turn the unit back on.

• Using a multimeter, verify that the compressor

pins show 2.2 – 2.5 ohms between all three

pins, and ensure that there are no shorts to

ground.

• If the ohm readings are within speciﬁcation,

replace the control module.

• If the fault still occurs, replace the refrigerator.

The pressure diﬀerence in the

cooling system is too high

(> 5 bar).

Minimum Speed

Error

The cooling system is too heavily

loaded, and the compressor

cannot maintain a high enough

RPM (1,850 RPMs).

• Remove all items from the unit, and let it cool

down to the set temperature while empty.

• Using a multimeter, verify that the compressor

pins show 2.2 – 2.5 ohms between all three

pins and ensure that there are no shorts to

ground.

• If the ohm readings are within speciﬁcation,

replace the control module.

5 Thermal Cut-Oﬀ

There is a lack of proper

ventilation.

• Remove the unit from the truck, and place it in

a well ventilated area. If the unit starts working

correctly, then the issue is a lack of ventilation

around the unit, or it is too hot in the truck.

• If the fault persists, replace the control module.

The cooling system is too heavily

loaded, causing the electronics

to overheat.

NTC Sensor Error The NTC sensor is defective. Replace the NTC sensor. 21

You may not actually see the voltage dip all the way to 10.4 VDC voltage cut out. The module has a voltage sensor that can read voltage more quickly than most

common Fluke meters. If any voltage drop is present, this issue must be corrected.

There is no way to bypass the module. Trying to do so with 12 VDC power will damage the compressor. The compressor is actually a three phase AC motor that

the module powers.

Heat must be removed from the rear of the refrigerator for proper operation. The design temperatures are 14 °F – 110 °F (-10 °C – 43 °C). Lack of ventilation can

lead to premature compressor failure or poor cooling capabilities. There must be a minimum of 36 square inches of opening to the outside for ventilation, and a

minimum of four inches of clearance behind the refrigerator. Two openings are recommended. Ventilation air must have a clear path in and a clear path out.

Although the LED light ﬂashes six times in succession, it will appear to blink continuously.