Electronic Expansion Valve; Exv Checkout Procedure; Is The Exv Bound And Communicating - Trane RTHD Troubleshooting Manual

EXV Checkout Procedure

Is the EXV bound
and
communicating?
CAUTION
Equipment
Damage Possible!
54

Electronic Expansion Valve

The Electronic Expansion Valve (EXV) is a flow device which regulates the flow of
refrigerant to the evaporator in order to match the compressor capacity. This
function increases the part load efficiencies.
The EXV is positioned by a 24VDC three phase bipolar stepper motor. The
electronics to drive the stepper motor are integral to the motor housing. The
position of the valve is determined by main processor calculations based on the
liquid level control algorithm. If the liquid level rises above the optimum value of
0.0" as displayed on the MP , the EXV will begin to close. If the liquid level falls
below the optimum value, the EXV will begin to open. To adjust the position of
the EXV, the main processor communicates a step value (0-6386 steps) command
to the EXV via the LLIDs bus cable.
Figure 34.Top of EXV
Connect TechView and get into Binding View. This will shut the chiller down.
Once in Binding View, verify that the EXV is bound.
Note: Please refer to Service Tool for questions concerning binding LLIDs and
getting into Binding View.
If there are multiple LLIDs that are not verified go to IPC troubleshooting.
If the EXV is not bound, try to bind it. If the EXV will not bind, it could be a
problem with the connector or the EXV itself. Take a close look at the connector
to make sure that all four wires are securely in place. It may be necessary to
remove the cap to check for broken or misplaced wires.
All unit built before October 1, 2002 (U02#####) used connectors that must be
replace if the cap is removed. If the cap is removed on any of these units cut out
LED
RLC-SVD05A-EN