Trane 4TWR6 Installer's Manual page 14

11.3 Defrost Control
Defrost controls have a selectable termination tem-
perature. As shipped, defrost will terminate at 47°F.
For a higher termination temperature, cut Jumper
J2 to achieve 70°F. See Service Facts shipped in
the outdoor unit for more information.
Pin Identification on J5 (See Illustration)
1. TEST_COMMON (Shorting to FRC_DFT
causes the control to initiate Forced Defrost.
Leaving this pin open results in the normal
mode of operation.)
2. FRC_DFT = Forced Defrost (Short TEST_
COMMON to this pin for two (2) seconds to
initiate a forced defrost. Remove the short
after defrost initiates.)
Defrost Control Checkout
Normal operation requires:
•
Status LED on board flashing 1 time/second
in standby or 2 times/second with a call for
heating or cooling.
•
24V AC between R & B
•
24V AC between Y, Y0 & B with unit operating
•
Defrost initiation when FRC_DFT pin is shorted to TEST_COMMON pin.
If a defrost control problem is suspected, refer to the service information in control box.
14
Defrost Board Detail
Jumper J2 J5 Test Pins
18-AC104D1-1E-EN