Carrier 69NT40-541-505, Operation And Service Manual

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T-368 7–20
7.18.2 Checking the Controller
a. Turn unit OFF.
b. With voltmeter set to read 20 volts DC, attach
the positive lead to MC1 of the 4-pin connector
and the negative lead to the TP9. Turn ON unit
and watch the volt meter. After a short delay, the
reading should remain unchanged at 0 volts. If
5VDC, make sure the jumper wire from MC1 to
MC8 is in place; if not, install and retest.
7.18.3 SMV Emergency Repair Procedure
In the event of an SMV failure, and replacement com-
ponents are not readily available, the system can be
bypassed by removing the SMV valve piston. To
remove the piston, do the following:
a. Perform a low side pump down (refer to Section
7.4 ).
b. Remove SMV powerhead by loosening the 2-1/8
inch diameter nut (see Figure 7.24 ) to relieve any
pressure and then sliding the powerhead out.
c. Remove the piston by loosening the Allen screw
and removing the piston and screw.
d. Install the powerhead assembly (without the pis-
ton) and torque to 35 to 40ft-lbs.
e. Open all valves.
f. Start the unit.
g. Adjust the suction service valve so that the
approximate temperature OR current limit is
maintained. For perishable loads, it is recom-
mended that the adjustment be made so that
the available capacity is slightly larger than the
load. The unit will cycle OFF and ON.
h. Once repair parts become available, repair as
required.
7.19 AUTOTRANSFORMER
If the unit does not start, check the following:
a. Make sure the 460VAC (yellow) power cable is
plugged into the receptacle (item 3, Figure 5.1 )
and locked in place.
b. Make sure circuit breakers CB-1 and CB-2 are
in the “ON” position. If the circuit breakers do not
hold in, check voltage supply.
c. There is no internal protector for this transformer
design; therefore, no checking of the internal
protector is required.
d. Using a voltmeter and with the primary supply
circuit ON, check the primary (input) voltage
(460VAC). Next, check the secondary (output)
voltage (230VAC). The transformer is defective
if output voltage is not available.
7.20 CONTROLLER
7.20.1 Handling Controller
CAUTION
!
Do not remove wire harnesses from con-
troller unless you are grounded to the
unit frame with a static safe wrist strap.
CAUTION
!
Unplug all controller connectors before
performing arc welding on any part of the
container.
The guidelines and cautions provided herein should be
followed when handling the Controller/DataCORDER
module. These precautions and procedures should be
implemented when replacing the module, when doing
any arc welding on the unit, or when service to the
refrigeration unit requires handling and removal of the
controller.
a. Obtain a grounding wrist strap (Carrier Transi-
cold P/N 07-00304-00) and a static dissipation
mat (Carrier Transicold P/N 07-00304-00). The
wrist strap, when properly grounded, will dissi-
pate any potential electrostatic buildup on the
body. The dissipation mat will provide a static-
free work surface on which to place and/or ser-
vice the controller.
b. Disconnect and secure power to the unit.
c. Place strap on wrist and attach the ground end
to any exposed unpainted metal area on the
refrigeration unit frame (bolts, screws, etc.).
d. Carefully remove the controller, refer to Section
7.20.4 . Do not touch any of the electrical con-
nections if possible. Place the module on the
static mat.
e. The strap should be worn during any service
work on the controller, even when it is placed on
the mat.
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