Mountaineer 4WD V6-4.0L VIN E (1999)
Aspirator: Customer Interest
A/C - Erratic or Insufficient Temperature Control
Article No.
99-8-8
05/03/99
CLIMATE CONTROL - ERRATIC OR INSUFFICIENT
TEMPERATURE CONTROL - EATC EQUIPPED
VEHICLES - SERVICE TIP
LIGHT TRUCK:
1995-1999 EXPLORER
1997-1999 MOUNTAINEER
ISSUE
Concerns of erratic or insufficient temperature control, where temperature control does not match setpoint, or where temperature gradually wanders away
from setpoint have arisen. These concerns may be caused by various items that are listed in this Service Tip TSB article.
ACTION
Follow Service Tips indicated to aid in normal diagnosis of the Electronic Automatic Temperature Control (EATC) system.
SERVICE TIP
Refer to the following diagnostic procedure according to the symptoms listed if no Diagnostic Trouble Codes (DTCs) are obtained from the EATC
self-test, which should be performed prior to any other diagnosis.
Vehicles with "No/Erratic temperature control," or "System works in Auto, but not in Manual mode" symptoms:
Drive actuator in both directions while visually checking actuator for movement.
1.
If there is movement, remove actuator and visually che6k blend door where the actuator rod inserts for cracks. The instrument panel does not have
to be removed for this operation. If the door is cracked, order a service plenum. Refer to the Service Plenum Tips in this article.
2.
If there is no movement, diagnose system according to pinpoint tests in the appropriate Explorer/Mountaineer Workshop Manual.
Vehicles with "System does not maintain setpoint temperature" or "Setpoint is reached but system gradually cools" symptoms:
Inspect the in-car temperature sensor aspirator tube for proper connection at both ends. Also check to make sure the in-car temperature sensor housing is
attached to AND FIRMLY seated to the dash panel. The sensor is mounted on two (2) pins. It is possible for the sensor to be attached to the pins but not
seated against the dash panel which will cause this symptom.
EATC ASPIRATION TEST
This test will determine if the In-Car Temperature Sensor (ICTS) is receiving enough aspiration. A lack of aspiration can result in an incorrect ICTS
reading and cause the automatic temperature control to act erratically with symptoms like: EATC blowing too cold or too warm.
1.
Cut a piece of toilet paper or tissue paper about 2.5x2.5 cm (1x1") (paper towel will not work).
2.
Turn the key on, turn fan speed to HIGH BLOWER, select PANEL or VENT mode.
3.
Place the piece of tissue paper over the aspirator grille opening, if aspiration (suction) is present, the tissue paper should "stick" to aspirator grille.
4.
Slowly lower the fan speed to LOW BLOWER. The tissue paper should still "stick" to aspirator grille.
5.
Turn fan to HIGH BLOWER, then turn fan OFF. Tissue paper should fall off.
6.
If the tissue paper falls off the aspirator grille when the fan is ON:
a.
Check that the aspirator hose is properly connected at both ends (at plenum case and ICTS).
b.
Check for proper size aspirator hole in heater plenum (19 mm (3/4") 1999 model year only).
c.
Check that the ICTS is properly sealed against dash panel with no gaps.
d.
Check for kinks and cuts in the aspirator hose.
