![background image](http://html1.mh-extra.com/html/carrier/vector-6500/vector-6500_operation-and-service-manual_2563864217.webp)
7
−
84
62-11389
Alarm
NO.
Steps
Alarm/Cause
Corrective Action
P177 CHECK EVAP SUPERHEAT
•
TRIGGER–ON: With the unit running in Test 12, after the microprocessor closes the EVXV to 0%,
evaporator pressure fails to drop by 20 psig (1.36 bar) or fails to go below 0 psig / bar
OR
the
EVXV appears not to be opening to the full capacity position.
•
UNIT CONTROL:
Engine and Standby Operation: Pretrip will fail and display
“PRETRIP FAIL AND COMPLETED”.
•
RESET CONDITION: Auto Reset if Pretrip is started again 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, clear the
alarm(s). (See Note 1 page 7
−
2.) Operate the unit through the appropriate modes to see if any active alarm
occurs. Continue with the steps below as necessary.
1
Check Refrigerant Level
Check refrigerant charge.
Refer to Section 8.6.2.
2
Check System Pressures
Install manifold gauge set and check
and compare compressor dis-
charge & suction pressures with
those shown on the microprocessor
display.
Suction and Evaporator Outlet pressures must be
above 3 psig (0.2 bar.)
Suction, Evaporator Outlet & Discharge Pressures
must have the same reading on gauges & on
microprocessor display.
NOTE: Microprocessor Suction (CSP) and
Evaporator (EVOP) pressure readings have a
maximum value of 100 psig (7.5 bar.) The actual
pressure must be lower than 100 psig in order to
perform this test.
3
Check EVXV
a. Visually inspect EVXV for
damage.
Check to see if coil is seated on valve properly.
b. Inspect EVXV coil and wire
connections.
No physical damage to harness.
No damage, moisture, or corrosion in connectors.
c. Check coil resistance.
See Section 8.8.6.
d. Check EVXV operation.
See Section 8.8.6.
e. Check basic refrigeration system.
Pressures normal. Compressor operation normal.
f. Check the EVXV electrical
system.
Check for good continuity in all circuits from micro to
EVXV.
g. Inspect component and wire
connections.
No physical damage to harness.
No damage, moisture, or corrosion in connectors.
h. Inspect harness & control box
connector pins & terminals. (See
wiring schematic Section 10.)
No physical damage to harness.
No damage, moisture, or corrosion in connectors.