Important Diagnostic Consideration (cont)

TM 10-4110-262-13&P

0028 00

Symptom

Corrective Action

Defrost LED is off when the unit is in the

Check for 24 VDC between Pin 4 and Pin 2.

defrost mode

Note the malfunctioning LED and continue to operate

unit.

Run an ice bath test on the sensor. See sensor

calibration data in WP 0002 00

Temperature displayed is out of range

Check that the unit controller 12/24 V selector is in the

24 V position

Check the thermostat sensor

Unit is not working

Check overload protector LED. If on, check overload

protector.

Check F4 fuse on the printed circuit board in the RU

electrical enclosure

Check for 24 VDC between Pin 2 and Pin 9

Replace unit controller

Unit is stopped by the AC overload

Check for 24 VDC between Pin 5 and Pin 9

relay, but the AC overload LED is off

Note the malfunctioning LED and continue to operate unit.

Compressor does not run

Check for 24 VDC between Pin 6 and Pin 9

Replace controller if no power.

Unit is indexed to heat but does not run

Check for 24VDC on Pin 10 and Pin 2

If no power, replace controller.

END OF WORK PACKAGE

0028 00-9/(10 Blank)