Electrical Maintenance
90
h. Wires L1, L2, and L3 should be connected
respectively to terminals L1, L2, and L3
on PC1.
i.
The 9-pin wire connector between the
PSM and the LV control harness should be
clean and tight.
j.
The electric motor must be wired
correctly.
2. Check PC1 and PC2 to make sure that one of
them is not faulty (contacts stuck closed).
3. If all of the wiring is correct, and the relays
and contactors are acceptable, but the electric
motor still runs backwards, switch the Brown
wire and the Black wire from the PSM at PC2:
Black to T1, Gray to T2, and Brown to T3. If
the electric motor now runs correctly, it is
probably wired incorrectly.
If the electric motor does not run at all:
1. Make sure that the unit is turned On, that
Electric Standby has been selected in the
Operator Menu, and that the power supply is
connected and turned On.
2. Check the CH-06 wire to the PSM for
continuity to the CH circuit (chassis ground).
If there is no continuity to the CH circuit,
check the CH-06 wire for continuity.
3. Check for battery voltage (12 volts) at the
7E-03/7EA wire to the PSM. Battery voltage
should be present. If not, check the 7E circuit
to pin 1 in the J6 connector on the base
controller. Also make sure that the
microprocessor display is on and that the
microprocessor is calling for Heat or Cool.
4. Check for battery voltage at the 7EB-01 and
7EC-01 wires at the PSM. Battery voltage
should be present on one of these wires when
the correct AC voltage is present on L1, L2,
and L3. If battery voltage is not present, the
PSM is faulty.
5. Check for battery voltage on the 7EB-01
terminal at PC2 and on the 7EC-01 terminal at
PC1. Battery voltage should be present at one
of these terminals. If not, check the continuity
of the 7EB-01 and 7EC-01 wires.
6. Check the continuity of the RED wires on the
phase contactors. The RED wires must have
continuity.
7. Check the CH circuits at PC1 and PC2 for
continuity to a chassis ground. If the CH
circuits do not have continuity to a chassis
ground, check the CH wires.
8. Check the continuity of the BLK wires on the
phase contactors. The BLK wires must have
continuity.
9. If the CH circuits and BLK wires do have
continuity to CH, the contactor that has
battery voltage present at 7EB-01 (PC2) or at
7EC-01 (PC1) is faulty.
Evaporator Heaters
Test the resistance of each evaporator heater by
disconnecting it from the circuit and checking it
with an ohmmeter. The resistance of each
evaporator heater should be approximately
122 ohms.
Transformer (460 Vac Units Only)
The transformer is used in units equipped to use
460 Vac for electric standby operation. The
transformer converts 460 Vac to 230 Vac to power
the condenser and evaporator fans.
Test the transformer as follows:
1. Connect the electric standby power receptacle
to a 460 Vac power supply.
2. Check for AC voltage between the primary
terminals H1, H2, and H3 on transformer.
Approximately 460 Vac should be present
between each pair. If the voltage is not
acceptable, check the power supply and check
the L1, L2, and L3 circuits (including any
contactors), the FB-1, FB-2, and FB-3 fuses,
and the TH1-01, TH2-01, and TH3-01 circuits
back to the transformer for continuity. If the
voltage is acceptable, go to the next step.
3. Check for AC voltage between the secondary
terminals X1, X2, and X3 on transformer.
Approximately 230 Vac should be present
between each pair. If not, the transformer is
probably faulty.
