6/23/2021
Verifying Controller Signal to EXV
1. If the system is running (no defrost active), go to
Settings→System Enable
and set it to
No
to
force a pump down. Disconnect power to the condensing unit, and the evaporator.
2.
With no power applied to the evaporator terminal block
, safely disconnect the wire harness
connector from the controller to expose the 4 pins that connect to the EXV cable, as shown in the
picture below.
3. Reconnect power to the evaporator only to turn the controller back on.
4. Using a voltmeter, place the test leads between pins 1 & 3, and pins 2 & 4 as shown in the pictures
below. Set the meter to measure DC volts.
5. On the controller display, set
System Enable
back to
Yes
and wait 1 to 2 minutes for the controller
to enable cooling (open freezer door if needed to warm up the box slightly so the controller can
attempt to signal the valve open).
6. With the meter test leads touching pins 1 and 3, when the controller signals that the output to
the valve reached the desired position (between 35% and 65%, visible via
Status→EXV
), the meter
should read approximately 12 to 16 Volts DC for a few seconds, then read approx. zero volts. Set
System Enable
back to
No
to have the controller send the signal to close. Again, with the meter
test leads touching pins 1 and 3, watch the voltmeter for the momentary bump in DC volts (12 to
16 VDC) when the signal to the valve reaches its final position (0%, visible via
Status→EXV
) then
back to near zero volts.
7. Repeat Step 5 again with meter leads touching pins 2 and 4. Repeat the test several times with
both pairs of pins if needed to confirm if the controller is functioning properly or not. If the
momentary DC voltage jump is detected with the meter following the preceding steps, the
controller is working properly. Proceed to troubleshoot the wire harness and the EXV.
8. If no voltage is detected at any point in time after following steps 3 thru 6, replace the controller
board.