Carrier VECTOR 6500 Operation & Service Manual page 188

Alarm
Steps
NO.
86 CHECK UL2 CIRCUIT
•
TRIGGER–ON: Rear Unloader (UL2) circuit is shorted. (The UL2 output from the microprocessor
(3MP23) is negative, so the circuit will not be shorted to ground, but is shorted either within UL2
itself, or to a positive wire.)
•
UNIT CONTROL: Engine and Standby Operation: alarm only.
•
RESET CONDITION: Auto Reset when the UL2 Coil current (amp) draw is normal, or alarm may
NOTE: Follow the steps below until a problem is found. Once a repair or correction has been made, the active
alarm should clear itself (see 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 Rear Unloader (UL2) Coil
a. Inspect Rear Unloader (UL2) coil &
connector.
b. Check resistance of coil.
c. Check amp draw of coil.
2 Check Rear Unloader (UL2) Current Draw
Use Component Test Mode to test
actual current draw of the circuit.
(Refer to Section 5.2.2.)
3 Check Rear Unloader (UL2) Coil Wiring
Inspect harness & control box con-
nector pins & terminals. (See wiring
schematic Section 10.)
Alarm/Cause
be manually reset via keypad or by turning the unit off, then back on again.
Corrective Action
No damage to coil.
No damage, moisture, or corrosion in connector.
Refer to Section 2.12 for correct electrical values.
Cannot be opened (infinite ohms), shorted (Zero
Ohms) or shorted to ground.
Refer to Section 2.12. Use ammeter.
Refer to Section 2.12 for correct electrical values.
View current draw in Data List.
No physical damage to harness.
No damage, moisture, or corrosion in connectors.
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