Tranquility
®
22 (TZ) Series
R e v. : A u g u s t 4 , 2 0 2 1
C l i m a t e M a s t e r Wa t e r-S o u rc e H e a t P u m p s
48
C L I M AT E M A S T E R WAT E R - S O U R C E H E AT P U M P S
Troubleshooting
General
If operational difficulties are encountered, perform
the preliminary checks below before referring to the
troubleshooting charts.
• Verify that the unit is receiving electrical supply power.
• Make sure the fuses in the fused disconnect switches
are intact.
After completing the preliminary checks described
above, inspect for other obvious problems such as
leaking connections, broken or disconnected wires, etc.
If everything appears to be in order, but the unit still fails
to operate properly, refer to the “DXM2 Troubleshooting
Process Flowchart” or “Functional Troubleshooting Chart.”
DXM2 Board
DXM2 board troubleshooting in general is best summarized
as verifying inputs and outputs. After inputs and outputs
have been verified, board operation is confirmed and the
problem must be elsewhere. Below are some general
guidelines for troubleshooting the DXM2 control.
Field Inputs
Conventional thermostat inputs are 24VAC from the
thermostat and can be verified using a voltmeter between
C and Y1, Y2, W, O, G. 24VAC will be present at the
terminal (for example, between “Y1” and “C”) if the
thermostat is sending an input to the DXM2 board.
Proper communications with a thermostat can be verified
using the Fault LED on the DXM2. If the control is NOT in
the Test mode and is NOT currently locked out or in a retry
delay, the Fault LED on the DXM2 will flash very slowly
(1 second on, 5 seconds off), if the DXM2 is properly
communicating with the thermostat.
Sensor Inputs
All sensor inputs are ‘paired wires’ connecting each
component to the board. Therefore, continuity on pressure
switches, for example can be checked at the board
connector. The thermistor resistance should be measured
with the connector removed so that only the impedance
of the thermistor is measured. If desired, this reading can
be compared to the thermistor resistance chart shown in
Table 7. An ice bath can be used to check the calibration
of the thermistor.
Outputs
The compressor and reversing valve relays are 24VAC
and can be verified using a voltmeter. For units with ECM
blower motors, the DXM2 controls the motor using serial
communications, and troubleshooting should be done
with a communicating thermostat or diagnostic tool.
The alarm relay can either be 24VAC as shipped or dry
contacts for use with DDC controls by clipping the JW1
jumper. Electric heat outputs are 24VDC “ground sinking”
and require a voltmeter set for DC to verify operation. The
terminal marked “24VDC” is the 24VDC supply to the
electric heat board; terminal “EH1” is stage 1 electric heat;
terminal “EH2” is stage 2 electric heat. When electric heat
is energized (thermostat is sending a “W” input to the
DXM2 controller), there will be 24VDC between terminal
“24VDC” and “EH1” (stage 1 electric heat) and/or “EH2”
(stage 2 electric heat). A reading of 0VDC between
“24VDC” and “EH1” or “EH2” will indicate that the DXM2
board is NOT sending an output signal to the electric heat
board.
Test Mode
Test mode can be entered for 20 minutes by pressing the
Test pushbutton. The DXM2 board will automatically exit
test mode after 20 minutes.
WARNING!
HAZARDOUS VOLTAGE! DISCONNECT ALL
ELECTRIC POWER INCLUDING REMOTE DISCONNECTS
BEFORE SERVICING.
Failure to disconnect power before servicing can cause
severe personal injury or death.
⚠
WARNING!
⚠
