Refrigerant Thermistors - Daikin FTXTA30AW Service Manual

ESIE17-19C | Part 2. Troubleshooting

2.4.2.8. Refrigerant thermistors

Technical specification
A single type of thermistor is used; the resistance vs. tempera-
ture characteristics is shown in below table "Thermistor resist-
ance / temperature characteristics (type 1)".
Location
Piping diagram
See "Outdoor unit" on
page 117.
Check procedure
Mechanical check
PRELIMINARY ACTIONS
1. Switch off the Daikin unit via the user interface.
2. Switch off the Daikin unit with the field supplied circuit breaker.
3. Locate the thermistor and check if thermal contact with the piping or ambient is ensured.
Electrical check
I
NFORMATION
If a thermistor check fails, replace the thermistor.
PRELIMINARY ACTIONS
1. Switch off the Daikin unit via the user interface.
2. Switch off the Daikin unit with the field supplied circuit breaker.
3. Remove plate work when required.
PROCEDURE
1. From the table in the appendix
2. Measure the temperature of the thermistor using a contact thermometer.
W : R
ARNING
When reconnecting a connector to the PCB, do not apply force, as this may damage the connector or connector pins of
the PCB.
3. Unplug the connector from the appropriate PCB and measure the resistance between the pins listed in the table in the
appendix ("Component checklist" on page
- Compare the measured resistance with the range determined by the lower and higher temperature.
4. If the measured resistance does not match the listed value, the thermistor must be replaced.
I
NFORMATION
All thermistors have a tolerance of 5%.
E.g. R3T air thermistor - main PCB - connector S90: pin 1-2 type 1:
• Measured temperature with contact thermometer: 23.1°C.
• Unplug the sensor and measure the resistance between S90: 1-2: 21.86 kΩ.
Page 60
Optimized Heating 4
Wiring diagram
See "Outdoor unit" on
page 114.
("Component checklist" on page
F
ISK OF IRE
118).
Description
The thermistors are used to measure the temperature at multiple
locations inside the Daikin unit. The measured temperatures are
processed by the main board.
Switch box
See "Outdoor unit" on
page 118.
118), select the thermistor that must be checked.
2.4. Component checklist
Component overview of unit
See "Outdoor unit" on page 118.
19/08/19 | Version 1.1