UNIT SERVICE
HCV & HCVR Evaporative Cooling & Gas Heating
Page 22 of 26
Unit overheats and locks out limit switch
1.
Gas valve stuck in open position. Clean or replace valve.
2.
Inadequate air delivery from blower. Check blower speed and for obstructions. Check for excessive
system static pressure.
3.
Defective fan switch. Fan switch AFS should allow fan to run on when unit is turned off to cool heat
exchanger/s. Replace switch.
4.
Dirt on fan blades or clogged filter pads. Clean fan and/or replace filter pads.
5.
Defective limit switch. Replace switch.
6.
System fan motor cutting out on overload. Check for high or low voltage. Check for defective
motor or motor overload.
System fan motor fails to operate
1.
Loose wiring connection. Make sure all wiring connections are tight.
2.
Motor trips overload. Reset and check with load amp test. Check overload set correctly.
3.
Faulty selector switch. Replace.
Burner flames are yellow or tend to ‘float’
1.
Gas input too high due to oversized injectors. Consult manufacturer for orifice size.
2.
Gas line pressure above that specified on data plate. Install high pressure regulator if line pressure
cannot be reduced.
3.
Exhaust fans causing fault draft. Provide opening to admit adequate fresh air to plant room to
eliminate negative pressure. Provide make up air if necessary.
4.
Improper flueing. Refer AGA installation Code AG601 – 1992. S. Dirty flue tube. See burner
cleaning instructions.
Primary aeration incorrect
1.
Discard burner damper/s with natural gas.
2.
Fully close burner damper/s with manufactured gas.
3.
Fully open damper/s with LPG.
4.
High humidity – When humidity is high, evaporation rates will be low, thus reducing efficiency of
cooler. Turn off water pump for best results.
5.
Fan running backwards – Reconnect motor for correct rotation.
6.
Fan running slow – Check motor amps. If below correct setting (refer data plate), readjust motor
pulley to increase speed.
7.
Belt slipping – tighten belt by adjusting motor mount. Replace belt if worn.
NOTE: If problem persists after checking through fault finding list, contact AIRA Pty. Ltd. Or your local gas
supply authority.