Trane RTWA 70-125 TON - Manual (Page 82)

82 RLC-SVD03A-EN
Variable Speed Fan System
Troubleshooting Procedure
ƽ WARNING
Live Electrical Components!
During installation, testing, servicing and troubleshooting of this
product, it may be necessary to work with live electrical
components. Have a qualified licensed electrician or other
individual who has been properly trained in handling live
electrical components perform these tasks. Failure to follow all
electrical safety precautions when exposed to live electrical
components could result in death or serious injury.
1. Go into the "Machine Configuration Menu" by performing the following
keystrokes: Service Settings, Previous, +, -, +, -, +, -, Enter. Check this
menu to be sure that "Fan Control" and "Variable Speed Fan" are Enabled
for both circuits. The "Fan Control" menu item was replaced with "Unit
Type" on units built after September 1, 1994 (SN U94HXXXXX and later).
Set "Unit Type" to RTA or RTU, which-ever applies. Be sure that "Variable
Speed Fan" is Enabled for both circuits.
2. Verify that all inverter power and control signal wiring is correct for the
affected circuit, using Figure 11-1 and Trane wiring diagram 2307-3328.
The wiring diagram is found in the Unit Wiring Section of RTAA-IOM-4 or
on the inside of the unit control panel door.
3. Attempt to start the compressor on the affected circuit. Twenty-five or
thirty seconds prior to compressor start, the variable speed fan inverter
contactor is energized. Be sure that this is heard. If not heard, attach an
AC voltmeter from pin J8-3 to ground on the compressor module. Reset
the control and look for a 115 volts reading on the voltmeter at pin J8-3,
25 to 30 seconds prior to compressor start. If this voltage is read but the
contactor does not pull in, check for an open circuit in the contactor coil or
an open circuit in the interconnecting wiring to the contactor.
4. Check the fan motor by completely bypassing the inverter. Disconnect
power from the unit and remove the three-phase power wiring from the
inverter. Connect it to the three-phase power wiring of the fan motor,
using splice wires with 1/4 inch male quick connects on both ends. Re-
apply power to the unit and reset the circuit being tested. Twenty-five or
thirty seconds before the compressor starts, the contactor that would
normally apply power to the inverter should pull in and the fan should run.
If the fan does not run, check the line fuses and contactor contacts.
5. Disconnect power from the unit and reconnect the inverter module. At
the same time, check for damaged wiring or loose quick connects on the
inverter.
6. Re-apply power to the chiller and check the compressor module power
supply, by reading the DC voltage levels from TP1 to the circuit board
edge ground and from TP2 to the circuit board edge ground. TP1 and TP2
are found on the upper lefthand side of the compressor module. The volt-
age at TP1 should be +5 ± .25 VDC. The voltage at TP2 should be +12 ±