Troubleshooting, Complete unit stoppage, Single circuit stoppage – Carrier WEATHERMASTER 48/50Z030-105 User Manual

Page 85: Service analysis, Restart procedure, Thermistor troubleshooting

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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

DAYSMON

Monday in Period

YES/NO

PER1MON

Yes

PER.1

DAYSTUE

Tuesday in Period

YES/NO

PER1TUE

Yes

PER.1

DAYSWED

Wednesday in Period

YES/NO

PER1WED

Yes

PER.1

DAYSTHU

Thursday in Period

YES/NO

PER1THU

Yes

PER.1

DAYSFRI

Friday in Period

YES/NO

PER1FRI

Yes

PER.1

DAYSSAT

Saturday in Period

YES/NO

PER1SAT

Yes

PER.1

DAYSSUN

Sunday in Period

YES/NO

PER1SUN

Yes

PER.1

DAYSHOL

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

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