CACH/CAHH/CAHJ & CACH/CAHH/CAHK
Air Handlers
• Installation, Operation and Maintenance Manual •
P/N 240008108, Rev. G [07/08/10]
55
Troubleshooting — CACH/CAHH/CAHK Units
NOTICE
Cassette operation can be controlled
through either a wall thermostat or an
optional infrared handheld controller.
To select control method, refer to DIP
switch options, Table 6, Page 32 .
Cooling-only units, Model CACH
Cooling only units require an 18 AWG
minimum low-voltage interconnecting wires
between the indoor and outdoor units. If the
cassett e controller is confi gured for wall ther-
mostat operation, then a wiring connection is
also required between the air handler and wall
thermostat. Refer to low-voltage interconnect
diagram, Figure 43, Page 51 , for low-voltage
connections.
NOTICE
Terminal “W” is required for units with
electric heat only.
Terminal “C” may not be needed on
some thermostats.
Th
e cassett e controller or wall thermostat will
switch the outdoor unit on and off through the
yellow, “Y,” low-voltage terminal.
When the thermostat is calling for cooling,
24 Vac can be measured across terminals “Y”
and “C” of the indoor or outdoor units.
For optional wall thermostat operation, 24 Vac
can also be measured across low-voltage ter-
minals “Y I” and “C” of the cassett e.
Th
e indoor unit contains an electronic anti-
short-cycle timer feature (ASCT) that will
prevent the outdoor unit from short cycling.
Aft er the room temperature is satisfi ed there
will be a three-minute delay before the out-
door unit is allowed to restart.
The cassette controller or wall thermostat
will also control the indoor fan by switching
high-voltage power to the fan motor with
the fan relay. When energized, high-voltage
power can be measured between the relay
output and the L2 terminal of the incoming
power supply.
For optional wall thermostat operation, 24 Vac
can also be measured across low-voltage ter-
minals “G” and “C” of the cassett e.
Heat Pump Units, Model CAHH/
CAHK
Heat pump units require an 18 AWG mini-
mum low-voltage interconnecting wire be-
tween the indoor unit and outdoor units. If
the cassett e controller is confi gured for wall
thermostat operation, then a wiring connec-
tion is also required between the air handler
and wall thermostat. Refer to low-voltage
interconnect diagram, Figure 43, Page 51 , for
low-voltage connections.
NOTICE
Terminal “O” is required for heat pump
operation. Th
e reversing valve is ener-
gized in cooling.
Terminal “W” is required for units with
electric heat only.
Terminal “C” may not be needed on
some thermostats.
Checking fuse link
WARNING
Electrical shock hazard
— Make sure
to fully disconnect all power to both the
indoor cassett e and outdoor unit where
indicated in these instructions.
To check if the fuse link has failed requires an
Ohmmeter reading across the limit switch.
Aft er disconnecting all power to the unit,
1.
disconnect the wires from the fuse link.
Th
en with an ohmmeter, check the con-
2.
tinuity across the fuse link.
If the fuse link is open, it must be re-
3.
placed.