Maytag MDG-120PHV, Installation Manual

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42 Maytag Co. 113395 - 9
FIRE SUPPRESSION SYSTEM THEORY OF OPERATION
While the dryer is in an idle state, or 20-seconds after the heat turns off, the microprocessor controller (computer)
monitors the thermistor probe, located in the top of the tumbler chamber, and records the minimum temperature.
If the minimum recorded thermistor probe temperature is greater than 120° F (48° C) and the microprocessor
controller (computer) detects a 50° rise in temperature, this will be the trip point and the fire suppression system
routine will activate.
While a drying cycle is in process and the heat has turned on at least once, the microprocessor controller
(computer) monitors the exhaust temperature transducer. If the drying cycle temperature set point is set greater
than 160° F (71° C) and the microprocessor controller (computer) detects an exhaust temperature rise 25° F
greater than set point, this will be the trip point and the fire suppression system routine will activate. If set point
is below 160° F (71° C), the trip point will be 185° F (85° C).
Once the fire suppression system routine is activated, the microprocessor controller (computer) will display
“S.A.F.E. SYSTEM ACTIVATED” and water will be injected into the tumbler chamber. Any time water is
being injected into the tumbler, the tumbler drive will turn the load for 1-second every 15-seconds. This process
will continue for a minimum of 2 minutes. After the 2 minutes have elapsed, the microprocessor controller
(computer) will check if the temperature remained above trip point; if so, the water will remain on. The
microprocessor controller (computer) will continue to check if the temperature is above trip point every 30-
seconds. If the water has been on for a constant 10 minutes, the water will be turned off, regardless of the
temperature, and the microprocessor controller (computer) will display “S.A.F.E. SYSTEM WAS ACTIVATED”.
If the temperature has dropped below trip point, the microprocessor controller (computer) will turn off the water
prior to 10 minutes.
SYSTEM RESET
After the microprocessor controller (computer) determines that the situation is under control and shuts the water
being injected into the basket (tumbler) off, the microprocessor controller (computer) display will read “S.A.F.E.
SYSTEM WAS ACTIVATED”, and the horn/tone will sound until turned off manually. To turn off the horn/tone
press the red “STOP/CLEAR” key on the keyboard (touch pad).
On dryers built before 02-02-2015
Pressing the red “STOP/CLEAR” key on the keyboard (touch pad) to turn off the horn will also reset the
microprocessor controller (computer).
On dryers built after 02-02-2015
Once the microprocessor controller (computer) displays “S.A.F.E. SYSTEM WAS ACTIVATED”, a service
call to your local dealer or Maytag is required to reset the microprocessor controller (computer). Qualified
personnel will inspect the dryer and, if it is found to be safe for operation, reset the control.
FIRE SUPPRESSION SYSTEM WATER VALVE CHECK
The operation of the water solenoid valve can be tested to ensure that the water supply system and valve are
functional. Before attempting a system check, be sure that
ALL water supply shutoff valves to the dryer are in
the OPEN position, the dryer must be in the “READY” Mode with no cycle loaded or in progress.
1. Press and hold the red “STOP/CLEAR” key (while in “READY” Mode and no cycle is in progress).
2. Press and hold the “A” key.
3. Water valve will open and water will be dispensed into tumbler area as long as both keys are held.