Chemical Injection Control - Maytag MFR Series Service Manual

Washers built prior to 2007 may not have a
chemical injection control signal box. MC5
control board washers have the relays and
transformer on the main washer control board,
they used to be on the signal board.
On MC4 OPL model washers there will be a
box on the back of the washer for chemical
supply signals.
Chemical Supply
Control Box
To remove the control box cover, remove
four #1 star head screws. The guide on
the reverse side of the cover plate shows
connection points for 8 supply signals, internal
and external power connections and the
voltage requirements. From the factory it is
set up to use internal voltage. The position
of the jumper determines the voltage source.
Remove the jumper plug to view the three
terminals. The middle terminal is the common,
the upper is marked INT for internal and
the lower is marked EXT for external. Most
installations use internal power.
There are connection points for up to 8
external supplies, but a maximum of 4
supplies per step can be set-up on the control
board. To connect wires to this terminal
connector, remove the connector, connect the
wires in the appropriate place and tighten the
screws. Plug the connector back on with the
screws facing up.

CHeMiCal inJeCTiOn COnTROl

160ma
Fast Blow
Fuse
Transformer
Power
Input
LEDs
Relays
Supply
Connections
The transformer receives line voltage, and
supplies 24VAC. There is a 160ma fast blow
fuse that protects the circuit.
Located above each relay is a small LED
labeled D1 through D8. These LEDs indicate
when the control board is trying to turn on the
relay.
3-12
Int / Ext
Power
Jumper
Control Signal Input
Wiring Harness