Installation, Operation & Maintenance Manual
16
FAULT FINDING
Fault
Possible Cause
Remedy / Action
Unit not operating.
No power to unit.
Check mains supply and main AHU isolator.
No Supply or Extract fans
running.
Fire link open.
Inspect fireman’s panel.
Defective damper end switch.
Check actuator operation and end switch
making when open.
No power to fans
Check control switch, fuses, MCB’s and
control circuit wiring.
No air volume.
Fan drive or motor failure
Inspect drive belts when applicable. Check
motor winding resistance.
Low air volume, fans
Running, airflow fail on.
Filters blocked
Remove packaging or replace.
Incoming phases crossed.
Check fan rotation. If incorrect change mains
incoming phases over. Not individual fans.
Refrigeration Circuits
4 Monthly Checks
At every service visit the following checks should be carried out: - Check the
suction and discharge pressures using a service gauge manifold and compare
them with the commissioning sheet. If there is any significant variation, then the
fault should be found and corrected. Refer to the troubleshooting chart. If on
inspection of the refrigeration pressures a refrigerant leak is suspected, open all
access panels to ensure the gas has dissipated to atmosphere.
Visually examine pipework and components for damage, wear and tear and oil
patches, the latter being indicative of a system leak.
Check that the high and low pressure switches are cutting out the compressors
at the correct settings.
High pressure switch cut-out 320psi
Low pressure switch cut-out 30psi
Low pressure switch cut-in 50psi
The gauges can then be removed from the system. Do not forget to replace
the security caps on the Schrader valves.
Annual Checks
Check all electrical connections for tightness.
Check all refrigeration connections with a foam or detergent leak detector.
