CACH/CAHH/CAHJ & CACH/CAHH/CAHK
Air Handlers
• Installation, Operation and Maintenance Manual •
P/N 240008108, Rev. G [07/08/10]
53
Th
e indoor unit contains an electronic anti-
short-cycle timer feature (ASCT) that will
prevent the outdoor condenser from short
cycling. Aft er the thermostat is satisfi ed there
will be a three (3) minute delay before the
condenser is allowed to restart.
While the wall thermostat is calling for cool-
ing and the ASCT delay has elapsed, 24 Vac
can be measured between terminals:
“Y” and “C” of the outdoor unit.
•
“Y1” and “C” of the cassett e.
•
“G” and “C” of the cassett e (fan signal).
•
Electric heat (optional)
Units with electric heat utilize a control relay
located on the circuit board in the control
box. When the wall thermostat is calling for
electric heat the relay will energize.
To check for electric heat operation, place the
wall thermostat in Heat mode with the set-
point temperature above room temperature.
Th
en place a clamp-on type ammeter on
1.
one leg of the incoming power supply.
When the unit is working correctly, the
2.
amp reading should correspond with the
values in the table below.
Th
e following current values apply when
3.
the unit is connected to a 230 Vac power
supply. Th
ese values include fan motor
current. If the supply voltage is differ-
ent, this will aff ect the amp draw of the
heater.
5kW = 22.7 A 3kW = 13.6 A 1.5kW = 6.9 A
Th
e electric heat relay can also be verifi ed
4.
by placing a voltmeter across the high-
voltage relay output terminal and the
incoming power L2 terminal.
If the unit is working correctly, the reading
5.
should be the same as measured across the
incoming power supply.
As a safety feature, an auto-reset limit switch
is located on the heater assembly.
The limit will interrupt power to the
1.
heater if an over-temperature condition
occurs.
Each limit switch is also equipped with a
2.
one-time fuse link.
Should electric heat temperatures rise
3.
above the auto resett ing limit switch, the
non-resetting, one-time fuse link will
open and the heater will remain off .
If this occurs the limit switch assembly
4.
must be replaced.(Contact EMI technical
service for a replacement.)
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.
With an ohmmeter, check the continuity
2.
across the fuse link.
If the fuse link is open, it must be re-
3.
placed.
For optional wall thermostat operation, 24
Vac can also be measured across the Cassett es
low-voltage terminals:
“G” and “C” (fan signal).
•
“W” and “C” (electric heat signal).
•
Troubleshooting — CACG/CAHG/CAHJ Units
(continued)