Trane RTWA 70-125 TON - Manual (Page 61)

RLC-SVD03A-EN 61
Module Power and Miscellaneous I/O
Test Points
There is only one test point associated with the EXV module. It is easily read
with a DC voltmeter by probing the PC board solder pad found in the upper
left hand corner of the module. The positive meter lead should be connected
to the pad while referencing the negative meter lead to the board edge
ground plane.
NOTE: Don't use the aluminum module enclosure as a reference as it
has an anodized surface with insulating properties. The DC voltage shall
be within the tolerance specified below. If not replace the module.
TP1: +5 volts DC ±5%
EXV Test
The EXV module has a built in test which is designed to allow the service
technician to confirm a problem with the EXV control system and to identify
which of the components of the system (the Valve/Stepper Motor assembly,
the EXV Module, or the interconnecting wiring) is at fault. The directions to
perform this test are given below:
EXV Test Procedure
1. Place the Chiller in the “STOP” mode using the Stop Button on the CLD.
2. Determine which refrigeration circuit is associated with the EXV valve you
want to test. Advance to the EXV TEST display in the Service Tests Menu.
3. Press the or keys to change the displayed “d” to an “E”, which
will enable or initiate the preprogrammed procedure. Display will auto-
matically return the item to disabled when the test is completed.
Electrical Integrity Test
4. Initially the UCM will perform an Electrical Integrity test on the valve's
stepper motor phases and associated wiring. If a failure is detected, it will
report a diagnostic indicating “EXV Elect. Drive CKT” at this time. This
Figure 16 Electronic Expansion Valve Location
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