4-21
©
2015 Mobile Climate Control
T-367 Rev. 05/2015
4.15 TEMPERATURE SENSOR CHECKOUT
a. An accurate ohmmeter must be used to check re
sistance values shown in Table 4-1.
b. Due to variations and inaccuracies in ohmmeters,
thermometers or other test equipment, a reading
within two percent of the chart value would be
considered acceptable. If a sensor is bad, the resist
ance value would usually be much higher or lower
than the value given in Table 4-1.
c. At least one sensor lead must be disconnected
from the controller before any reading can be tak
en. Not doing so will result in a false reading. Two
preferred methods of determining the actual test
temperature at the sensor are an ice bath at 32
°
F
(0
°
C) and/or a calibrated digital temperature me
ter.
Table 4-1 Temperature Sensor Resistance
Temperature
Resistance In Ohms
°
F
°
C
-20
-28.9
165,300
-10
-23.3
117,800
0
-17.8
85,500
10
-12.2
62,400
20
- 6.7
46,300
30
- 1.1
34,500
32
0
32,700
40
4.4
26,200
50
10.0
19,900
60
15.6
15,300
70
21.1
11,900
77
25
10,000
80
26.7
9,300
90
32.2
7,300
100
37.8
5,800
110
43.3
4,700
120
48.9
3,800
4.16 PRESSURE TRANSDUCER CHECKOUT
NOTE
System must be operating to check transduc
ers.
a. With the system running use the driver display and
manifold gauges to check suction and/or dis
charge pressure(s) simultaneously.
b. Determine with the gauges whether one or both
pressure readouts are correct. If one is correct, ex
change the pressure transducer locations. If the
problem moves with the transducer, replace the
faulty transducer.
c. If the driver display read out disagrees with both
values shown on the manifold gauges proceed to
step d.
d. Verify that the wiring to the transducer(s) is in
good condition.
e. Use a digital volt-ohmmeter to measure voltage
across the transducer connector corresponding to
terminals A & B. See Figure 4-17. The reading
should be 5.0 VDC.
f. Use a digital volt-ohmmeter to measure voltage
across the transducer at terminals A & C. See
Figure 4-17. Compare to values in Table 4-2. A
reading within two percent of the values in the
table would be considered good.
A
B
C
Figure 4-17 Transducer Terminal Location
4.17 REPLACING SENSORS AND TRANSDUCERS
a. Place main battery disconnect switch in OFF posi
tion and lock.
b. Tag and disconnect wiring from defective sensor
or transducer.
c. Remove and replace defective sensor or transduc
er. Sensor/transducer connections are fitted with
Schreader valves to facilitate replacement.
d. Connect wiring to replacement sensor or trans
ducer.
e. Checkout replacement sensor or transducer. Refer
to section 4.15 or 4.16 as applicable.
f. Repair or replace any defective component(s), as
required.
