The unit is not cooling
Check if the compressor is running, if not follow procedure “The indoor unit is working but the outdoor unit is not” If the compressor is running, check for a differential pressure across the compressor. If not, replace the compressor. If there is a pressure differential, but the pressures are not correct, follow the following procedure
1. Recover the refrigerant
2. Complete a full leak test
3. Open, check and clean the expansion device
4. Recharge to the correct refrigerant level
The unit is not heating
1. Check there is an electric heater kit fitted to the unit
2. Check the resistance across the heater is approx 26 Ohms, if not replace the heater element
3. Check that the controller set point is higher than the internal temperature
4. Check that there is a heating run signal from the controller, if not replace the controller
5. Check that the heater relay is functioning correctly, if not replace the relay
6. Check the heater thermal fuse assembly, is there a signal after the manual cut out switch, if not reset the switch and tray again
7. Check there is a signal after the auto reset cut out, if not replace the heater thermal fuse assembly
8. If the fault still cannot be found, repeat from step 1, if still can not be found, replace heater element and thermal fuse assembly
What is the max working pressure?
R407C Indoor and outdoor unit 29.5Bar
R410A Outdoor units 45Bar
R410A Indoor units 29.5Bar
What is the refrigerant charge? Sight glass not clear?
These units are charged to a site glass and system pressures. We can’t give a specific refrigerant charge as this will change dependant on the selected evaporator. Special note: for systems using a refrigerant with glide. Due to the nature of these refrigerants it is impossible to have a completely clear site glass all the time. Care should be taken to avoid over charging the system.
How do you pump down?
1. Close the liquid line service valve
2. Wait until the system cuts out on LP then close the suction service valve.
3. Remaining refrigerant in the evacuated areas should be fully recovered before breaking into the system.
The unit is going out on HP?
1. Check the condenser fan is operating
2. Check the condenser coil is not blocked
3. Check the refrigerant pressure to ensure the system is reaching high pressure, if not check the HP switch operation.
4. If none of the above, completely recover all the refrigerant and check the system for blockages
The unit is going out on LP?
1. Check the system pressures, if the system is not at low pressure check the operation of the LP switch.
2. Check is evaporators is iced up, if so de-ice and then run the system to find the cause
3. Is the evaporator fan running, if not find out why
4. If the system is low pressure and none of the above, recovery all the refrigerant and check the system for blockages. Pay special attention to the systems expansion device which is the most common place to find a blockage
What is the working pressure? What is the fan speed controller setting?
The working pressure should be set using the unit fan speed controller. Find the maximum ambient for the area and set the condensing temperature to 10°C above that.
How can the condenser fan be run at full speed? What is the orange link between terminals 40 and 41?
There is an orange link between terminals 40 and 41 allows the condenser fan to be ran at full speed. This requires removal if the unit fan speed control is required.
What is the max working pressure?
MRC+ units 29.5Bar
See individual max working pressures for indoor unit evaporators
What test pressures should be used?
Testing should be carried out in accordance with the latest BS EN 378 standard.
How does the interconnecting wiring work / how do you set it up?
If running on direct wire control, use the supply from terminal 8 to power your system controller. The controller run signal is wired to terminal 3.