Service Manual

TESTING
18” & 24” ADA Built-In Dishwashers
n
3-17
For Service Technician Use Only
Pressure Switch
The pressure switch is an overll safety device mounted on
the base located on the right front. A clear plasc tube (the
pressure switch hose) runs from the switch to the sump.
As the dishwasher tub lls with water, the air pressure in the
pressure switch hose increases. Normally, the control board
regulates the amount of me the water ll valve remains open.
If the water ll valve remains energized, the overlling of the
tub increases the air pressure in the pressure hose causing the
pressure switch to close and energize the drain pump.
This test will check the wiring to the pressure switch and the
pressure switch itself. The following items are part of the
pressure switch circuit.
n Harness/Connecon
n Pressure Switch
n Pressure Switch Hose
STRIP CIRCUIT - PRESSURE SWITCH
Figure 2 - Pressure Switch Strip Circuit
CONTROL BOARD
DRAIN PUMP
DRAIN PUMP
L1
CON1-2
DRAIN PUMP RELAY
(L)
RD
RD
BR
25 - 35 Ω
RD
RD
THERMAL
CONTROL BOARD
N
CON1-1
CON1-1
(N)(N)
BU
P
CON2-1
(PS)
PRESSURE
SWITCH (120 VAC)
BR
RD
Normally
Open
120 VAC
Test Procedure
1. Unplug dishwasher or disconnect power.
2. Remove access panel. Remove control board cover to
access control board.
3. Lay the dishwasher on its back. Use a small at-blade
screwdriver to unclip snaps around the drip-pan. Remove
drip-pan/oat switch to access under tub components.
4. Check hose connecons between the pressure switch and
sump. Ensure hose is routed correctly and not pinched or
crimped.
5. Verify there is no debris in the hose. Check hose for leaks.
Repair or replace as needed.
6. Check the following harnesses for connuity (refer to the
following chart).
Pressure Switch Continuity Check
Pressure Switch to CON1-2 (Brown Wire)
Pressure Switch to CON2-1 (Red Wire)
Pressure Switch to Drain Pump (Red Wire)
¾ If an open circuit is detected, check connecons
between control board, pressure switch, and drain
pump. Repair or replace as necessary.
¾ If all harness test good, proceed to step 7.
7. Check the pressure switch. Using an ohmmeter, measure
the resistance across the pressure switch terminals (refer
to the following chart).
Pressure Switch Continuity Check
No Pressure Switch Open -
Innite or High Resistance
Apply Pressure
(Blow into hose*)
Switch Closed -
Connuity (less than 3 ohms)
* When you blow into the pressure hose that is connected
to the switch, an audible “click” can be heard indicang
the switch has closed.
¾ If all pressure switch checks pass, connue to step 8.
¾ If the preceding checks did not pass, replace the
Pressure Switch.
8. Reassemble all parts and panels.
9. Plug in dishwasher or reconnect power and retest.
WARNING
Electrical Shock Hazard
Disconnect power before servicing.
Failure to do so can result in death or
electrical shock.
Replace all parts and panels before operating.