A change in the internal temperature above or below the set point indicates one of the following issues with the thermal management system:
- The compressor may not be turning on
- The internal heater may not be turning on
- The compressor cooling fan at the back of the monitor may not be working (causing the compressor to overheat)
- The internal blower may not be working (preventing cool or warm air from circulating inside the monitor).
Check the compressor
The compressor may not be turning on.
These voltages can be used to check its operation:
- The voltage between the brown and white (-ve and +ve) should always be 12V.
- The voltage between brown and green (-ve and C) should always be 5V.
- When the compressor is on maximum, the voltage between brown and yellow (-ve and T) is 3V.
- When the compressor is on minimum, the voltage between brown and yellow (-ve and T) is 0V.
- When the compressor is off, the voltage between brown and yellow (-ve and T) is 5V.
To test these voltages, change the ITEMP H0 setting:
Check the internal heater
The internal heater may not be turning on.
The heater is controlled by a relay in the DC fuse box at the back.
You can turn the heater on by setting the ITEMP to a high number. The signal from the system manager module triggers the heater relay and you measure 12V.
Check compressor cooling fan
The compressor has a fan to help if keep cool.
If the outside temperature is above 3oC , the outside fan is always on.
If the outside temperature is below 3oC , the outside fan is always off.
If the outside temperature is above 3oC and the cooling fan isn’t on, the compressor will heat up and it won’t be able to cool properly.
The compressor fan is controlled by a relay.
Check internal blower
The internal blower should always be on.
If it isn’t working, check the blower power is 12 V. These are the red and black blower wires at the bottom right of the DC fuse box, just above the compressor cable.
If you need to replace the blower at any stage, see this procedure.