MDPA2 FCA112515
©2012-2015 ZONEFIRST
®
Page 4
TROUBLESHOOTING
The MDPA2/MDP3 is a very simple control to troubleshoot, especially
with the LED indicators. The only other device needed is a simple
Volt/Ohm meter. Almost all problems can be traced to an external
component or wiring to/from the MDPA2. The following procedures
can help isolate the problem.
Zone(s) Not Calling
Each zone has a LED next to the zone damper plug-in jack, when a
zone is calling and that call is being recognized by the MDPA2/MDP3
that zone LED will be illuminated GREEN . Provided no other zone is
calling for the opposite mode, check the zone that is supposed to be
calling and the zone’s LED. If it is not on, check for 24VAC across
the thermostat terminal C and the Y, if a Cool call, W if a Heat Call, or
G if a Fan call. If there is no voltage here at the panel, the panel is
not getting the signal from the thermostat. The problem is mis-wiring,
a broken wire or a problem in the thermostat. To check the zone on
the panel, place jumper from R to Y, R to W or R to G to see that the
panel is operating properly.
Zone(s) Will Not Shut Off
If a zone will not stop calling, the Zone LED should still be illuminated
GREEN. Depending on the call disconnect the Y, W or G wire from
the terminal strip. The zone will drop out. Check the thermostat
wiring for a mis-wiring or short that keeps the zone calling. If the call
remains and the thermostat is disconnected, replace the panel.
Damper Motor Checkout
To checkout the dampers, the panel has a LED for each zone. This
illuminates GREEN when the dampers are to be OPEN, either on a
call or when all zones are satisfied. The damper position is confirmed
by the bi-color LED on the motor. When the panel zone LED is
Green, the motor LED must be Green also indicating the damper
being open. When the panel LED is not lit the damper should be
closed and this is confirmed by the damper LED being Red
.
Power LED Not On
If the Power LED is not Illuminated GREEN and there is 24VAC at the
transformer terminals, the MDPA has a built-in thermal fuse, (light
brown rectangle component below transformer terminals) that may be
open. To check, touch to see if component is hot. If it is hot, fuse is
open and must be reset. This is also indicative of a potential wiring
short.
Remove all wires (start with transformer wires) from the MDPA2
panel and check fuse (must be cool to the touch) to make sure it is
not hot. Place 24VAC wires back to transformer terminals on panel
and power LED should come back on. If it does not, replace board.
If it does light, begin adding the wires from each zone to the panel
one by one checking the power LED at each point. If the power LED
drops again check these wires for a potential short.
TRANSFORMER PHASING
When using separate transformers to power the MDP3 and MDPA2
panels it is required that all transformers be in phase with one
another. To check the transformer phasing use a voltmeter and
check for voltage on one leg of the 24V transformer connection on the
MDP3 panel to the opposite leg of the 24V transformer connection on
the MDPA2 panel. See the diagram below. The voltmeter should
read zero (0) Volts. If the voltmeter reads 24V or 48V, reverse the
leads of one of the transformer until the voltmeter reads zero (0) volts.
Reading zero volts proves the transformers are in phase with one
another.
MDPA2 Panel Wiring Diagram
20 Bushes Lane
•
Elmwood Park, New Jersey 07407-3204
USA
Telephone 1.877.604.1044 FAX 1.201.794.1359
R
C
24VAC 2
24VAC 1
R
C
24VAC
24VAC
0V
AC
MDP3
MDPA2
24V 40VA
Transformer
Voltmeter
24VAC 2
24VAC 1
24VAC 2
24VAC 1
0V
AC
24V 40VA
Voltmeter
