Wash Cycle Description; Wash System Components; Water Valve Operation And Checks; Pressure Switch Operation And Checks - Frigidaire FDB2410HIB Servicing

Section 3 Electronic Control And Testing

Wash Cycle Description

All of the wash cycles start with the drain pump running
to evacuate the sump of any water before clean water
enters the unit to start the wash cycle. The control
sends power to the water valve and water enters from
the top of the air gap on the left side of the tub. From
the air gap, water exits through a hose near the bottom
of the air gap to a port on the rear of sump. Water level
in the dishwasher will be just to the sides of the tub at
the completion of the fi ll cycle for a total of slightly less
then one gallon. The water fi ll is a timed event. The
unit uses a pressure switch as a safety to prevent an
over-fi ll condition. This pressure switch is mounted to
the right frame leg. The pressure tube connected to the
pressure switch is mounted to an air bell on the rear of
the sump. After the fi ll, the control starts the wash
motor, pulling water from the sump and into all of the
spray arms simultaneously for the cleaning cycle. The
water entering the wash pump, fi rst passes through the
three fi lters that are mounted in the sump. This removes
food particles from the wash water so only clean water is
sprayed back onto the dish load. At the same time the
wash motor is started throughout the cycle, the control
energizes the heater to maintain and increase water
temperature to improve cleaning and to activate the de-
tergent. The control is continually monitoring the water
temperature with the use of the thermistor. Water in the
tub will be pumped out and the tub refi lled throughout
the cycle to help improve water quality during the wash
cycle. The number of times this occurs depends on the
cycle selected. The last drain out will be at the end of
the dry cycle to insure all of the water has been removed
from the tub as the cycle ends.

Wash System Components

The Wash system is a combination of 5 sub systems:
1. Fill System which includes the water valve, air gap
and safety pressure switch.
2. Water Distribution System which includes the wash
motor and pump assembly, and three spray arms.
3. Filter System is made up of three fi lters.
4. Water Heating System is the heater and the safety
thermostat.
5. Drain System is the drain pump and connecting
hoses.

Water Valve Operation and Checks

The water valve is an electrically operated shut off valve
and is designed to handle incoming water pressure from
20 to 120 psi. There is a built-in fl ow washer to regulate
the rate of water fl ow into the dishwasher.
3-4
To check the water valve:
First select a wash cycle and allow the cycle to come to
the fi ll portion of the cycle, open the door and connect
meter leads to valve close door and check for voltage.
The solenoid can be checked for resistance this should
read 1K ohms. (See Figure 3-3)
Check Screen
Make sure gasket
is in place
Figure 3-3.

Pressure Switch Operation and Checks

Overfl ow protection is accomplished with a pressure
switch mounted to the right side frame behind the junc-
tion box. The pressure switch has a normally closed
contact for the water valve. If water in the tub over fi lls
the contact in the switch opens and disconnects power to
the water valve. A pressure tube from the switch loops
up the right side of the tub to the top of the air gap
then to an air chamber on the front of the sump.
To check the pressure switch:
Check the terminals on the switch for resistance. The
reading should be 0 ohms resistance. (See Figure 3-4)
Wires from Control
To
Water Valve
Figure 3-4.
Electrical
Connection