Rear Window Defogger - DaimlerChrysler LH New Yorker 1994 Electronic Service Manual

A/C—HEATER—ATC CONTROL SWITCH . . . . . . 1
GENERAL INFORMATION
GENERAL INFORMATION
For proper operation of the Rear Window Defogger
system refer to the Owner's Manual.
Vehicles equipped with an electrically heated rear
window defogger also have a 90 amp generator.
The system consists of a rear glass with two vertical
bus bars and a series of electrically connected grid
lines fired on the inside surface. A control switch and
a timer relay located in the A/C, heater or ATC con-
trol is used on all models (Fig. 1).
Fig. 1 Rear Window Defogger Typical
Circuit protection is provided by a fusible link,
located in the charging circuit, for the heated grid
circuit and by a fuse for the relay control circuit.
When the switch is turned to the ON position,
current is directed to the rear defogger grid lines. The
heated grid lines heat the rear glass to clear the
surface of fog or frost.
CAUTION: Grid lines can be damaged or scraped off
with sharp instruments, care should be taken in clean-
ing glass or removing foreign materials, decals or
stickers. Normal glass cleaning solvents or hot water
used with rags or toweling is recommended.
A/C—HEATER—ATC CONTROL SWITCH
The control switch and timer relay are integrated
into the A/C, heater or ATC controls (Figs. 2 and 3).

REAR WINDOW DEFOGGER

CONTENTS
page
. . . . . . . . . . . . . . . . . . 1
REAR WINDOW DEFOGGER
REPAIR GRID LINES, TERMINALS AND PIGTAILS
SERVICE PROCEDURES
Actuating the switch energizes the circuit allowing
current to flow through the grid lines for ten minutes.
Upon initial actuation, 5 minutes with each subse-
quent actuation or until either the switch or ignition
is turned off. An indicating lamp illuminates a lens
inlaid in the control switch.
Fig. 2 ATC Control Switch
Fig. 3 Heater Control Switch
SERVICE PROCEDURES
Electrically heated rear window defogger operation
can be checked in vehicle in the following manner:
(1) Turn ignition ON.
(2) Make sure defogger OFF.
(3) Using a ammeter on the battery. Turn the De-
fogger control switch ON, a distinct increase in am-
perage draw should be noted.
(4) The rear window defogger operation can be
checked by feeling the glass. A distinct difference in
temperature between the grid lines and adjacent clear
glass can be detected in 3 to 4 minutes of operation.
8N - 1
page
. . . . . . . . . . . . . . . . . . . 1
. 3