50
Table 36 — Alarm and Alert Codes (cont)
 
*Current imbalance alarm x.25 may be changed to warning x.27 after suc-
cessful start-up of the chiller.
†Compressors are equipped with 2 motor winding temperature thermistors.
Verify first that the problem is not a wiring error before using backup
thermistor.
 **Reset automatic first time, manual if repeated on the same date.
††Note that the high-pressure switch should trip before this alert is generated.
Check HPS operation if this alert is generated.
NOTES:
1. Low Oil Pressure Alert Criteria and Set Points
  Where: P
d
 = Discharge Pressure, P
s
 = Suction pressure,
  P
o
 = Oil pressure and P
e
 = Economizer pressure
  Two oil pressure set points are used. Oil Set point 1 is always 15 psig.
  a. If (P
d - 
P
s
) < 125, then Oil Set point 2 = 0.235 x (P
d - 
P
s
) + 0.588
  b. If (P
d - 
P
s
) >= 125 and < 165, then Oil Set point 2 = 2.0 x (P
d - 
P
s
) - 220.0
  c. If (P
d - 
P
s
) >= 165, then Oil Set point 2 = 0.6364 x (P
d - 
P
s
) + 5.0
The 2 set points are used by the control for the Low Oil Pressure alert trip
criteria below:
a. Oil Pressure is ignored during the first 5 seconds after a compressor is
started.
b. In period between 5 and 120 seconds after starting, the alert will be gen-
erated if (P
o
 - P
e
) < [(Oil Set point 1)/120] x (Compressor Run time in sec-
onds) for 3 consecutive readings
c. After 120 seconds of run time, the alert will be generated if:
1)(P
o
 - P
e
) < Oil Set point 1 for 15 seconds OR
2)(P
o
 - P
s
) < Oil Set point 2 for 25 seconds
2. (P
o
 - P
e
) is the Oil pressure differential displayed in     for Circuit A
and in     for Circuit B.
ALARM/ALERT
CODE
ALARM OR
ALERT
DESCRIPTION
WHY WAS THIS
ALARM GENERATED?
ACTION TAKEN
BY CONTROL
RESET METHOD
PROBABLE
CAUSE
71 Alert Circuit A Low Oil
Level/Flow
Level switch input open 
for 4th time in same day.
Circuit A shut down after 
4th failure in 24 hours.
Manual Low oil level, failed 
switch, wiring error, 
failed DSIO module
72 Alert Circuit B Low Oil
Level/Flow
Level switch input open 
for 4th time in same day.
Circuit B shut down after 
4th failure in 24 hours.
Manual Low oil level, failed 
switch, wiring error, 
failed DSIO module
73 Alert Circuit A Low Discharge 
Superheat
Superheat < 5 F (2.8 C)
for 10 minutes
Circuit A shut down Manual Faulty thermistor, trans-
ducer, or EXV, or Econo-
mizer. Motor cooling 
solenoid stuck open.
74 Alert Circuit B Low Discharge 
Superheat
Superheat < 5 F (2.8 C)
for 10 minutes
Circuit B shut down Manual Faulty thermistor, trans-
ducer, or EXV, or Econo-
mizer. Motor cooling 
solenoid stuck open.
75 Alarm Comp. A1 Max. Oil 
Delta P, check oil line
(Discharge press - Oil 
press) > 100 PSI for 
more than 5 seconds
Comp. A1 shut down Manual Plugged oil filter, closed 
oil valve, bad oil sole-
noid, compressor oil 
check valve stuck, oil line 
check valve stuck, 
plugged oil strainer
76 Alarm Comp. A2 Max. Oil 
Delta P, check oil line
(Discharge press - Oil 
press) > 100 PSI for 
more than 5 seconds
Comp. A2 shut down Manual Plugged oil filter, closed 
oil valve, bad oil sole-
noid, compressor oil 
check valve stuck, oil line 
check valve stuck, 
plugged oil strainer
77 Alarm Comp. B1 Max. Oil 
Delta P, check oil line
(Discharge press - Oil 
press) > 100 PSI for 
more than 5 seconds
Comp. B1 shut down Manual Plugged oil filter, closed 
oil valve, bad oil sole-
noid, compressor oil 
check valve stuck, oil line 
check valve stuck, 
plugged oil strainer
78 Alarm Comp. B2 Max. Oil 
Delta P, check oil line
(Discharge press - Oil 
press) > 100 PSI for 
more than 5 seconds
Comp. B2 shut down Manual Plugged oil filter, closed 
oil valve, bad oil sole-
noid, compressor oil 
check valve stuck, oil line 
check valve stuck, 
plugged oil strainer
79 Alarm Comp. A1 Failed Oil 
Solenoid
Diff. Oil pressure
> 2.5 PSI during period 
after oil pump starts and 
before oil solenoid opens
Comp. A1 not allowed to 
start
Manual Faulty oil solenoid valve
80 Alarm Comp. A2 Failed Oil 
Solenoid
Diff. Oil pressure
> 2.5 PSI during period 
after oil pump starts and 
before oil solenoid opens
Comp. A2 not allowed to 
start
Manual Faulty oil solenoid valve
81 Alarm Comp. B1 Failed Oil 
Solenoid
Diff. Oil pressure
> 2.5 PSI during period 
after oil pump starts and 
before oil solenoid opens
Comp. B1 not allowed to 
start
Manual Faulty oil solenoid valve
82 Alarm Comp. B2 Failed Oil 
Solenoid
Diff. Oil pressure
> 2.5 PSI during period 
after oil pump starts and 
before oil solenoid opens
Comp. B2 not allowed to 
start
Manual Faulty oil solenoid valve
LEGEND
CCN — Carrier Comfort Network
CPM — Compression Protection Module
DGT — Discharge Gas Temperature
EWT — Entering Water Temperature
EXV — Electronic Expansion Valve
FSM — Flotronic™ System Manager
HPS — High-Pressure Switch
LCW — Leaving Chilled Water
LWT — Leaving Water Temperature
MCT_SP — Maximum Condensing Temperature Set Point
MTA — Compressor Must Trip Amps
SCT — Saturated Condensing Temperature
SST — Saturated Suction Temperature
W/C — Water-Cooled
WSM — Water System Manager