Carrier Transicold X4 7300, Руководство по эксплуатации и обслуживанию

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1. Remove switch as outlined in preceding section
2. Connect ohmmeter or continuity light across
switch terminals. Ohmmeter will indicate resis-
tance and continuity light will be illuminated if
switch closed after relieving pressure.
3. Connect switch to a cylinder of dry nitrogen.
(See Figure 8.39 )
4. Set nitrogen pressure regulator higher than
open setting for switch being tested. For pres-
sure switch settings refer to
Section 2.9 .
5. Close valve on cylinder and open bleed-off valve.
6. Open cylinder valve. Slowly close bleed-off valve
and increase pressure until the switch opens. If
light is used, light will go out and if an ohmmeter
is used, the meter will indicate open. Close cylin-
der valve. Slowly open bleed-off valve (to
decrease pressure) until switch closes (light will
illuminate or ohmmeter will indicate open).
8.9.12 Pressure Transducers
The compressor discharge pressure transducer (CDP)
has a range of 0 to 500 PSIG (0 to 34.0 bar) while the
compressor suction pressure transducer (CSP) and
evaporator outlet pressure transducer (EVOP) have a
range of -14.7 to 100 PSIG (-1 to 6.8 bar). When com-
paring the transducer reading in Unit Data to the read-
ing on a manifold gauge, keep in mind the following:
1. The compressor discharge pressure reading in
Unit Data will never read less than 0 bar/psig,
even if it is exposed to a vacuum (such as when
evacuating the system).
2. If the compressor discharge pressure trans-
ducer has lost power or the signal is not return-
ing to the module the reading in Unit Data will
default to 305 to 315 psig (20.75 to 21.43 bar).
Comparisons in this pressure range are not con-
clusive.
3. The compressor suction pressure and evapora-
tor pressure transducers will never read higher
than 100 psig, even if actual pressure is higher.
4. If the compressor suction pressure or evapora-
tor pressure transducer has lost power or the
signal is not returning to the module the reading
in Unit Data will default to 55 to 60 psig (3.74 to
4.08 bar). Comparisons in this pressure range
are not conclusive.
To test the transducer wiring, do the following:
1. Verify that the wiring to the transducer is correct.
NOTE
The CDP connector is identified with a red
tape band while the CSP connector is identi-
fied with a blue band.
2. If required, power the transducer circuit by plac-
ing the unit in PC Mode, refer to Section 5.3.2 .
Check Voltage to transducer connector. Voltage
reading between connector position 2 (positive)
and position 1 (negative) should be 5.0 VDC.
3. To check the signal wiring, check continuity
between the transducer connector position 3
and the following connector: CDP = 2MM
− 10,
CSP = 2MM − 9, EVOP = 2MM − 17
4. If voltage and signal wire are good, replace the
transducer. The transducer may be removed by
disconnecting the connector and quickly back-
ing it off the Schrader valve fitting. Torque
replacement transducer 13 to 15 ft/lb (17.6 to
20.3 Nm).
8.9.13 Defrost Air Switch
Figure 8.40 Defrost Air Switch Test Setup
1. Ohmmeter or Continuity Device
2. Adjustment Screw (0.050” socket head size)
3. Low Side Connection
4. Pressure Line or Aspirator Bulb (Carrier Transi-
cold part number 07-00177-01)
5. Magnehelic Gauge (Carrier Transicold part
number 07-00177-00)
6. High Side Connection
- - - - -
NOTE
If the DTT temperature is above 40°F
(4.4°C) defrost cannot be initiated and the
Message- Center will display “CANNOT
START DEFROST CYCLE”.
1. Check air switch tubing. Red tube is to be con-
nected to the high connection and routed below
the coil. Clear tube is to be connected to the low
connection and routed above coil. Check condi-
tion and mounting of air sensing fittings on the
coil end of both tubes. See
Figure 2.3
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2
3
4
5
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