Rheem 310 Series Service Instructions Manual page 21

Component test 5
T Sensor Testing: 310 Series Heat Pumps have five independent thermistors which are
utilised to monitor temperatures at various locations around the system. These thermistors
connect to and are monitored by the control board and are known as 'T sensors'.
All five T sensors are identical and each can be tested as follows:
Warning - Ensure power is isolated before conducting this test.
Unplug the relevant T sensor from the
control board and remove the T sensor
from its location so its temperature will be
the same as the ambient air temperature
(As sensor T4 detects the ambient air
temperature it may remain in position for
this test). Using a multimeter on the kilo-
ohms scale, measure between the two pins
of the T sensor plug*. As the resistance of
each sensor will change according to its
temperature, the resistance measurements
for each sensor will need to be checked
against the Temperature/Resistance Table
shown below and the value then compared
to the ambient air temperature.
*Note: The sensor strip plug socket test points are quite small, Fine Probe Adapters (part
number WH0020082) can be utilised as probe extensions. Alternatively small pins may be
used however ensure good contact is made when testing.
Sensor
T0
T1
T2
T3
T4
T Sensor Temperature / Resistance Table
The table below sets out the resistance of the T sensors for a given water or air
temperature.
Temperature
Degrees C
0
10
20
30
40
50
60
70
80
TM025 Rheem Heat Pump Service Instructions REV: B
Date of Issue: 02/08/07
This document is stored and maintained electronically by
Water temperature leaving the condenser
Water temperature entering the condenser
Evaporator temperature
Compressor discharge temperature
Ambient air temperature
Service. All printed copies not bearing this statement in RED are deemed "uncontrolled".
Monitors
Resistance (All T Sensors)
Kilo-ohms
23.73
15.45
10.31
7.037
4.905
3.485
2.521
1.853
1.384
20
Part Number
056006