Carrier VECTOR 6500 Operation & Service Manual page 140

Alarm
Steps
NO.
13 HIGH DISCHARGE PRESSURE (ALARM 75 WILL ALSO ACTIVATE)
•
TRIGGER–ON: Compressor discharge pressure switch (HP1) contacts are open. HP1 contacts
open when the discharge pressure rises to 465 psig (31.6 bar.)
•
UNIT CONTROL:
•
RESET CONDITION: Auto Reset after 15 minutes if the compressor discharge pressure falls below
350 psig (23.8 bar), 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 (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 System Pressures
Install manifold gauge set and check
and compare compressor discharge
& suction pressures with those
shown on the microprocessor.
2 Check Airflow Through Condenser Coil
a. Inspect condenser & radiator.
b. Check airflow (with unit running.)
c. Check condenser fans.
3 Check For Refrigerant Overcharge
Check refrigerant charge.
4 Check HP1 Switch
Inspect switch & connector pins &
terminals.
5 Check HP1 Switch Harness
a. Inspect harness & control box
connector pins & terminals. (See
wiring schematic Section 10.)
b. Check for shorted circuit in harness,
and continuity through the harness.
6 Check HP1 Switch
Check switch operation.
Alarm/Cause
Engine Operation: Engine and unit shutdown and alarm.
Standby Operation: Refrigeration system shutdown and alarm with PSCON
still energized.
7−7
Corrective Action
Suction & Discharge Pressures must have the same
reading on gauges & on microprocessor display.
Pressures must be in the normal range for ambient &
refrigerated compartment temperature conditions. If
discharge pressure is in normal range, proceed to
step 4.
NOTE: Microprocessor suction (CSP) and evaporator
(EVOP) pressure readings have a maximum value of
100 psig (7.5 bar) The actual suction pressure must
be lower than 100 psig in order to perform this test.
Ninety percent or more of the coil surface must be
undamaged. Condenser coil and radiator must be
clean.
Even airflow through the entire coil.
No "dead" spots.
Both fans should operate correctly. Check rotation,
air should be pulled in through the grill, and discharge
into the engine compartment.
Refer to Section 8.6.2.
No physical damage to switch.
No damage, moisture, or corrosion in connector.
No physical damage to harness.
No damage, moisture, or corrosion in connectors.
Energize Circuit. (See Note 2, page 7−2.) Check for
voltage from SP5, through switch and SP15 to micro-
processor terminal 2MP29.
Test switch, refer to Section 8.8.7 step b.
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