T-340
7–24
7.23 Controller
7.23.1
Handling Modules
CAUTION
!
Do not remove wire harnesses from module unless you are grounded to the unit frame with a
static safe wrist strap.
CAUTION
!
Unplug all module connectors before performing arc welding on any part of the container.
The guidelines and cautions provided herein should be followed when handling the modules. These precautions
and procedures should be implemented when replacing a module, when doing any arc welding on the unit, or when
service to the refrigeration unit requires handling and removal of a module.
1. Obtain a grounding wrist strap (Carrier Transicold P/N 07-00304-00) and a static dissipation mat (Carrier
Transicold P/N 07-00277-00). The wrist strap, when properly grounded, will dissipate any potential static
buildup on the body. The dissipation mat will provide a static-free work surface on which to place and/or ser
-
vice the modules.
2. Disconnect and secure power to the unit.
3. Place strap on wrist and attach the ground end to any exposed unpainted metal area on the refrigeration
unit frame (bolts, screws, etc.).
4. Carefully remove the module. Do not touch any of the electrical connections if possible. Place the module
on the static mat.
5. The strap should be worn during any service work on a module, even when it is placed on the mat.
7.23.2
Controller Troubleshooting
A group of test points (TP, see
) are provided on the controller for troubleshooting electrical circuits (see
schematic diagram sections). A description of the test points is provided in
.
NOTE
Use a digital voltmeter to measure AC voltage between TP’s and ground (TP9), except for TP8.
Table 7–2 Test Point Descriptions
Test Point Description
TP1
Not used in this application.
TP2
Check if the high pressure switch (HPS) is open or closed.
TP3
Check if the water pressure switch (WP) contact is open or closed.
TP4
Check if the internal protector for the condenser fan motor (IP-CM) is open or closed.
TP5
Check if the internal protectors for the evaporator fan motors (IP-EM1 or IP-EM2) are
open or closed.
TP6
(if equipped) - Check if the controller liquid injection valve relay (TQ) is open or closed.
TP7
Check if the controller economizer solenoid valve relay (TS) is open or closed.
TP8
Not used in this application.
TP9
Chassis (unit frame) ground connection.
TP10
Check if the heat termination thermostat (HTT) contact is open or closed.
