MHGRV-X Field Technical Guide
APPENDIX C - REHEAT EXPANSION MODULE
25
LED Diagnostics
The Reheat Expansion Module is equipped with 4 LEDs that can be
used to verify operation and perform troubleshooting.
See Figure 10 below for the LED locations. The LEDs associated
with these inputs and outputs allow you to see what is active without
using a voltmeter. The LEDs and their uses are as follows:
Operation LEDs
POWER - This green LED will light up to indicate that 24 VAC
power has been applied to the Expansion Module.
STATUS - This green LED will light up and blink every 10 seconds
according to valve position. One blink per 10%. Example: valve
position is 67%. STATUS LED will blink 6 times every 10 second
cycle. The STATUS LED will stay on solid during the 2 minute fl ush
cycle. See Table 10 below.
No. of
Blinks
STATUS LED
1 - 10 Per 10% Valve Position
SOLID During 2 Minute Flush Cycle
Table 10: STATUS LED Blink Codes
LED Diagnostics & Troubleshooting
Communication LED
COMM - This amber LED will light up and blink once for every
good packet received. Packets should be sent once every second,
so Comm LED should blink the same, once every second. COMM
LED should blink simultaneously on all modules.
Binary Input LED
COMPRESSOR ENABLE - This green LED will light up when
the Reheat is enabled.
LED Troubleshooting
“POWER” LED: When the Reheat Expansion Module is powered up,
the POWER LED should light up and stay on continuously. If it does
not light up, check to be sure that the power wiring is connected to the
board, the connections are tight, and the transformer is powered. If after
making all these checks, the POWER LED does not light up, the board
is probably defective.
“STAT” LED:
When the board is fi rst powered up, the STAT LED
will do the following:
On for 10 seconds
Blinks 30 times
Status code is repeatedly blinked every ten seconds to
indicate valve position
Figure 10: Reheat Expansion Module(s) Wiring
24VAC
GND
COMM
GND
ENABLE
BLACK
WHITE
RED/GRN
GRN/RED
COND/REHEAT
YS102608 R0
WATTMASTER
CONTROLS INC
2013
COMM
STATUS
COMM LED
POWER
LED
STATUS LED
COMM
STATUS
COMPRESSOR
ENABLE
LED
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