Trane RTHC - Application Of Solid-state Starters; The starter is a pre-wired platform consisting of a 3-pole bypass contactor...

Electronic Expansion Valve
48 RTHC-SVD01B-EN
8-3. EXV Motor and Wiring Checkout Procedure
If the integrity of the EXV motor is suspect, use the following procedure
to check the expansion valve motor and wiring.
8-3 a. Motor Winding Resistance Checkout
1. With UCP2 powered, press the “STOP” button once.
2. In the Service Test menu, change “EXV Control is:” to “Manual”.
NOTE: The red alarm light on the front panel will energize and remain
steady anytime an item in the Service Test menu is set to something
other than “AUTO”.
3. In the Service Test menu, change “Expansion Valve Position:” to
100% open.
4. Unplug the J2 connector (power) on the 1U3 stepper module.
5. Unplug the J8 connector from the 1U3.
6. Measure the resistance of the EXV motor windings across the dis-
connected J8 connector. Use 8-2for acceptable resistance val-
ues.
7. If the valve does not pass the resistance test, either the connec-
tor, wiring to the valve, or the valve is defective.
8. Verify EXV wiring and connector integrity before condeming the
EXV.
9. Re-connect all plugs and change “EXV control is:” back to “Auto”.
Table 8-2: EXV Resistance Values
Pin Connections
Acceptable
Resistance Range
Nominal
Resistance
(Ohms)
W1: J8-4 to J8-2
50 milli ohm to
5 ohm 1.68
W2: J8-3 to J8-1
50 milli ohm to
5 ohm 1.68
NOTE: All other points to each other and to ground are open
circuits.