Service manual

A DJM3.2 MANUAL
Main Board Pots Located on the Right Side of the DJM3.2 and 3.3
Near
Terminal
Pot Name Function Page #
S
D Sen Cal Discharge Sensor Calibration 25
U
Dis SP Cal Discharge Set-Point Calibration 25
Z
BMS Cal BMS Calibration (volt or current input) 16
OR
Room Cal Room Sensor Calibration 26
+
Hi Service Manual Firing Pot for Service Mode 28
SP
Reset Ratio Reset Ratio (for ambient or room reset)* 12
SUB-BOARD POTS LOCATED AT THE TOP OF THE CONTROL
1
Low Fire Low Fire RPM (Combustion Analyzer Required) 31
G
Curve Match Curve Matching RPM (Combustion Analyzer Req’d) 31
* Note re possible incorrect label diagram and page 14
IX. STATUS LIGHTS
There are 4 LED lights. These lights have different meanings based on their rate of flashing.
• SLOW FLASH (2 second rate)
• FAST FLASH (1 second rate)
• IRREGULAR (2 short on flashes followed by a long off)
LED 1
OFF Discharge temperature is ok, or the unit is shut off (normal operation).
SLOW FLASH (2 sec) Discharge temperature is below 40°F but the low limit bypass timer is
still operating.
FAST FLASH (1 sec) Unit is locked out because discharge sensor resistance is greater
than 4000-ohms or less than 880-ohms.
ON Unit is locked out on low limit. (Also outputs 24 VAC on L/L contacts.) If there
was a pre-purge problem while the S/A fan was running, the pre-purge
problem light would flash until a low limit trip occurs, then the failure status
would switch to low limit. Therefore, a low limit problem may have actually
been caused by a pre-purge problem.
NOTE: If the low limit has been disabled (dipswitch 8 off) then the status light indication will not
operate.
LED 2
OFF The heat exchanger ignition pre-purge is completed or the combustion
blower is not running.
SLOW FLASH Trouble is with the combustion air blower tachometer or the DJM3.2 is
receiving a tachometer signal that is not consistent with the combustion
blower status. If there is a call for heat and the combustion blower IS NOT
RUNNING the DJM3.2 has likely detected a false or grounded tachometer
signal. Remove all three wires to terminals O, YS, and G. If the combustion
blower fails to start, check the combustion motor and or motor wiring. If the
motor starts, replace the speed sensor and/or magnet.
Page 6 Revised: 3/11/99