Ford 2001 Ranger, Manual

Page: 297 / 1218

412-02-3 412-02-3 Heating and Ventilation
•
DTC B1254 Air Temperature External Sensor
DIAGNOSIS AND TESTING
Circuit Failure
Heating/Defrosting/Ventilation System
— The interface adapter assembly (IAA) module
Diagnostic Trouble Code (DTC) Definition
uses the ambient temperature sensor to
The following DTCs relate to the
monitor the temperature of the outside air. If
heating/defrosting/ventilation system:
the ambient temperature sensor reads less than
-40
°
C (-40
°
F) or greater than 90
°
C (194
°
F)
•
DTC B1238 Over Temperature Fault
for 30 seconds, the IAA module sets DTC
— The positive temperature coefficient (PTC)
B1254 and assumes the temperature to be
switching module uses an overtemperature
215
°
C (419
°
F).
switch that is mounted on the heater plenum
•
DTC C1776 Heater System Failure
assembly to monitor the temperature of the
— The positive temperature coefficient (PTC)
PTC heater cores. The PTC overtemperature
heater core consists of two cores (A and B).
switch is a normally closed switch that opens
The PTC switching module drives core A,
when an overtemperature condition occurs.
core B or both core A and core B depending
The switch is set to open at 93
°
C-100
°
C
on ignition key cycling and temperature. The
(199
°
F-212
°
F). If the switch opens, the PTC
PTC switching module switches between core
switching module pulls the overtemperature
A and core B between ignition key cycling
fault line to the interface adapter assembly
and turns on both cores at low temperatures. If
(IAA) module low (0 volts), and the IAA
the core that is turned on by the PTC
module sets DTC B1238.
switching module is open or is in an
•
DTC B1249 Blend Door Failure
overcurrent condition, the PTC switching
— The interface adapter assembly (IAA) module
module must see a time of 45-60 seconds on
monitors the range of blend door position. The
the suspect heater core before a DTC code can
IAA module sets DTC B1249 if it detects the
be set. Afterwards, the PTC Switching Module
blend door is not moving for 30 seconds of
disables that core, switches to the other core,
applied voltage or senses the blend door
and pulls the interface adapter assembly (IAA)
feedback to be less than 0.15 volts or greater
module control line for the faulted core low (0
than 4.85 volts. The IAA module also sets
volts). The IAA module sets DTC C1776
DTC B1249 if the autocalibration routine of
when it detects either control line (core A or
the blend door operation sets the full warm
core B) low. It is possible to see an
position at less than three volts or the full cool
intermittent NO-HEAT condition on one core.
position at more than two volts.
•
DTC C1779 Blower Switch Failure
•
DTC B1250 Air Temperature Internal Sensor
— The interface adapter assembly (IAA) module
Circuit Failure
monitors the blower speed signals from the
— The interface adapter assembly (IAA) module
climate control blower switch. The IAA
uses the in-car temperature sensor to monitor
module sets DTC C1779 if it detects an
the temperature of the passenger compartment.
invalid combination of the blower speed inputs
If the in-car temperature sensor reads less than
for more than 30 seconds.
-40
°
C (-40
°
F) or greater than 90
°
C (194
°
F)
for 30 seconds, the IAA module sets DTC
B1250 and assumes the temperature to be
25
°
C (77
°
F).
2001 Ranger EV, 01/2001