Carrier VECTOR 1550 Series - Evap (Evaporator) Motor Overheated

62-61753-21
7-47
Alarm
NO.
Steps
ALARM / CAUSE
CORRECTIVE ACTION
77 EVAP (EVAPORATOR) MOTOR OVERHEATED
 TRIGGER-ON: The evaporator fan motor Internal Protectors (IP-EVM1 AND 2) is open.
 UNIT CONTROL: Engine and standby operation: Evaporator will shut down.
 RESET CONDITION: Auto Reset after a 15 minute off time when motor overload input is within limits,
or change to engine operation, or alarm may be manually reset via keypad or by turning the unit off,
then back on again.
NOTE: Follow the steps below until a problem is found. Once a repair or correction has been made, the active
alarm should clear itself (refer to reset condition above). Operate the unit through the appropriate modes to see if
any active alarm occurs. Continue with the steps below as necessary.
1
Check Evaporator Fan Blades for Free Operation
a. Visually inspect evaporator fan for
any foreign material or damage or
anything that will prevent the blade
and motor from turning freely
Blower wheel must be in good condition.
No sticks or other material obstructing its movement
No ice build-up preventing blade rotation.
2
Check For Power At 4MP3
b. If 12VDC
Alarm should have cleared itself.
a. If no power (0VDC)
Continue with step 2 below.
3
Check IPC Circuit
a. Use Component Test Mode to test
actual current draw of the circuit.
(Refer to Section 5.1.2.)
Component FET or board LED (refer to Table 5-1)
must be illuminated.
View current draw in Data List.
Refer to Section 2.12 for normal current values.
b. Unplug the connector to the evap-
orator fan motor and check voltage
on IP-EVM (white) wire.
12 VDC between pin 4 in the engine harness connect-
or and Ground.
c. Check MPQC9.
There should be 12 VDC from MPQC9 to Ground.
d. Test continuity through IPC.
Should be 0 Ohms. If the evaporator fan motor is ex-
tremely warm, allow it to cool off, then recheck IPC
continuity.
e. Test IP circuit from evaporator fan
motor junction box to microproces-
sor.
12 VDC at 4MP3
4
Check Evaporator Fan Motor Contactor
a. Inspect the wire connections to the
contactor.
No signs of overheating of the contactor. Wiring is
routed correctly to the contactor.
b. Check tightness of the contactor
wire connections
Tighten with screwdriver and check for discoloration of
wires.
5
Perform Pretrip
a. Clear Active Alarm list, then run
Pretrip & check for any new
alarms.
Any active alarms must be corrected and cleared be-
fore proceeding.
Additional steps on the next page.