Is The Sensor Reading Accurately - Trane RTHD Troubleshooting Manual

CAUTION
Equipment
Damage Possible!
Is the sensor
reading
accurately?
58
Liquid Level Sensor
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
the old connector and splice in a new section of cable and a new connector. See
Section 2-IPC Overview for instruction on installing a new cap.
If the sensor is bound, try to turn the LED on with a magnet. If the light will not
turn on there could be a problem with the sensor. Try to turn the light on in
Binding View. With the light on, hold the magnet to the LED. The LED should get
brighter. If it doesn't get brighter this may indicate a problem with the sensor,
connector, or bus. 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. If there is no problem found with the connector, and
the sensor will not bind, then replace the sensor.
In order for this test to work, the condenser pressure must be at least 60 psi
greater than the evaporator pressure.
1 Run the circuit to increase differential pressure.
2 Shut the unit down. Close the liquid line service valve. Place a gage on the
suction line (the gage is a secondary check to verify that suction transducer is
reading correctly). Enable pump down (the unit must be in the stopped mode
to enable pump down). This can be done from either DynaView (Set Points
tab) or TechView (Compressor Service View). Pump down will be
automatically terminated when the suction pressure reaches 5 psig.
If the ambient temperature is below 50 deg F the unit will do an operational
pumpdown just before shut down. This operational pumpdown is only active on
units with software version 18 and later and design sequence B0 and later. If the
unit does a pumpdown skip step 2.
3 During pump down watch the liquid level.
RTAC- This can be done in TechView in Status View under the Circuit tab or no
the DynaView (software version 18 and later only) on the refrigerant tab.
RTHD- This can be done in TechView in Status View under the Circuit tab or on the
DynaView on the reports tab under evaporator.
4 The liquid level should go to -1.1 or less as the refrigerant is removed from the
evaporator.
5 As soon as pump down is complete, open the expansion valve.
6 RTAC - This can be done from the DynaView on the Set Point tab or in
TechView in Compressor Service View.
7 RTHD- This can be done from the DynaView on the Settings tab under Manual
Control Settings or in TechView in Compressor Service View.
8 With the valve open, the liquid level should increase. Depending on operating
conditions, the level may not go all the way to +1.0 or more, but the level
should increase.
9 If there is no change in the liquid level during this test there may be problem
with the liquid level sensor, canister, or the lines going to the canister.
RLC-SVD05A-EN