Troubleshooting, Complete unit stoppage, Single circuit stoppage – Carrier WEATHERMASTER 48/50Z030-105 User Manual
Page 85: Service analysis, Restart procedure, Thermistor troubleshooting

85
Table 70 — Time Clock Menu
Daylight Savings Stop Week (DS.SP
→
SP.WK) — This is
the stop week of the month for daylight savings. The week can
be set from 1 to 5.
Daylight Savings Stop Day (DS.SP
→
SP.DY) — This is the
stop day of the week for daylight savings. The day can be set
from 1 to 7 (Sunday=1, Monday=2, etc.).
Daylight Savings Minutes To Subtract (DS.SP
→
MIN.S) —
This is the amount of time that will be removed from the time
clock after daylight savings ends.
TROUBLESHOOTING
The scrolling marquee display shows the actual operating
conditions of the unit while it is running. If there are alarms or
there have been alarms, they will be displayed in either the cur-
rent alarm list or the history alarm list. The Service Test mode
allows operation of the compressors, fans, and other compo-
nents to be checked while the unit is not operating.
Complete Unit Stoppage —
There are several condi-
tions that can cause the unit to not provide heating or cooling.
If an alarm is active which causes the unit to shut down,
diagnose the problem using the information provided in
the Alarms and Alerts section on page 94, but also check for
the following:
• Cooling and heating loads are satisfied.
• Programmed schedule.
• General power failure.
• Tripped control circuit transformers circuit breakers.
• Tripped compressor circuit breakers.
• Unit is turned off through the CCN network.
Single Circuit Stoppage —
If a single circuit stops
incorrectly, there are several possible causes. The problem
should be investigated using information from the alarm and
alert list.
Service Analysis —
Detailed service analysis can be
found in Tables 71-73 and Fig. 13.
Restart Procedure —
Before attempting to restart the
machine, check the alarm list to determine the cause of the
shutdown. If a shutdown alarm for a particular circuit has
occurred, determine and correct the cause before allowing the
unit to run under its own control again. When there is problem,
the unit should be diagnosed in Service Test mode. The alarms
must be reset before the circuit can operate in either Normal
mode or Service Test mode.
Thermistor Troubleshooting —
The EDT, OAT,
RAT, LAT, T55, T56, and T58 space temperature sensors use
10K thermistors. Resistances at various temperatures are listed
in Tables 74 and 75.
THERMISTOR/TEMPERATURE SENSOR CHECK — A
high quality digital volt-ohmmeter is required to perform this
check.
1. Connect the digital voltmeter across the appropriate ther-
mistor terminals at the J8 terminal strip on the main base
board.
2. Using the voltage reading obtained, read the sensor tem-
perature from Tables 74 and 75.
3. To check thermistor accuracy, measure temperature at
probe location with an accurate thermocouple-type
temperature-measuring instrument. Insulate thermocou-
ple to avoid ambient temperatures from influencing
reading. Temperature measured by thermocouple and
temperature determined from thermistor voltage reading
should be within 5° F (3° C) if care was taken in applying
thermocouple and taking readings.
If a more accurate check is required, unit must be shut down
and thermistor removed and checked at a known temperature
(freezing point or boiling point of water) using either voltage
drop measured across thermistor at the J8 terminal, or by
ITEM
EXPANSION
RANGE
POINT
DEFAULT
TIME
TIME OF DAY
HH.MM
Hour and Minute
00:00
TIME
DATE
MONTH,DATE,DAY AND YEAR
MNTH
Month of Year
multi-text strings
MOY
DOM
Day of Month
0-31
DOM
DAY
Day of Week
multi-text strings
DOWDISP
YEAR
Year
e.g. 2003
YOCDISP
SCH.L
LOCAL TIME SCHEDULE
PER.1
PERIOD 1
PER.1
→DAYS
DAY FLAGS FOR PERIOD 1
Period 1 only
PER.1
→DAYS→MON
Monday in Period
YES/NO
PER1MON
Yes
PER.1
→DAYS→TUE
Tuesday in Period
YES/NO
PER1TUE
Yes
PER.1
→DAYS→WED
Wednesday in Period
YES/NO
PER1WED
Yes
PER.1
→DAYS→THU
Thursday in Period
YES/NO
PER1THU
Yes
PER.1
→DAYS→FRI
Friday in Period
YES/NO
PER1FRI
Yes
PER.1
→DAYS→SAT
Saturday in Period
YES/NO
PER1SAT
Yes
PER.1
→DAYS→SUN
Sunday in Period
YES/NO
PER1SUN
Yes
PER.1
→DAYS→HOL
Holiday in Period
YES/NO
PER1HOL
Yes
PER.1
→OCC
Occupied from
00:00
PER1_OCC
00:00
PER.1
→UNC
Occupied to
00:00
PER1_UNC
24:00
Repeat for periods 2-8
HOL.L
LOCAL HOLIDAY SCHEDULES
HD.01
HOLIDAY SCHEDULE 01
HD.01
→MON
Holiday Start Month
0-12
HOL_MON1
HD.01
→DAY
Start Day
0-31
HOL_DAY1
HD.01
→LEN
Duration (Days)
0-99
HOL_LEN1
Repeat for holidays 2-30
DAY.S
DAYLIGHT SAVINGS TIME
DS.ST
DAYLIGHT SAVINGS START
DS.ST
→ST.MN
Month
1 - 12
STARTM
4
DS.ST
→ST.WK
Week
1 - 5
STARTW
1
DS.ST
→ST.DY
Day
1 - 7
STARTD
7
DS.ST
→MIN.A
Minutes to Add
0 - 90
MINADD
60
DS.SP
DAYLIGHTS SAVINGS STOP
DS.SP
→SP.MN
Month
1 - 12
STOPM
10
DS.SP
→SP.WK
Week
1 - 5
STOPW
5
DS.SP
→SP.DY
Day
1 - 7
STOPD
7
DS.SP
→MIN.S
Minutes to Subtract
0 - 90
MINSUB
60