Caravan AWD V6-201 3.3L (1991)
Air Duct: Customer Interest
Low Heater Performance - Diagnosis/Repair
NO: 24-05-94 Rev. A
GROUP: Heater & A/C
DATE: Dec. 23, 1994
SUBJECT:
Low Heater Performance Diagnosis/Repair
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 24-05-94, DATED MAR. 11, 1994 WHICH SHOULD BE REMOVED
FROM YOUR FILES. REVISIONS ADD 1995 AND ES VEHICLES, AND ARE HIGHLIGHTED WITH **ASTERISKS**.
MODELS:
1991 - **1995**
(AS) Town & Country/Caravan/Voyager
**1992 - 1995
(ES) Chrysler Voyager**
SYMPTOM/CONDITION:
Poor heater system performance at low ambient temperatures consisting of one or more of the following symptoms:
A)
Heater discharge duct temperature drops off at engine idle speed.
B)
Poor heater system performance resulting in cooler than expected average cabin temperature.
C)
Driver's side floor cold due to lack of direct heater air flow (1993 or 1994 models).
Low heater performance may be caused by many factors within the heater and A/C system, the engine cooling system and/or the engine electronic
management system. Proper diagnosis is essential to avoid additional customer inconvenience and needless component changes. It is very important for
the Service Advisor/Technician to FIRST determine the specific customer complaint, and then match it to the three descriptions listed above.
DIAGNOSIS/REPAIR PROCEDURE:
If the customer complaint is SYMPTOM A or SYMPTOM B, perform the heater output test first. If the customer complaint is SYMPTOM C, go
directly to the SYMPTOM C repair procedure.
HEATER OUTPUT TEST
With the engine idling at normal operating temperature, set the temperature control lever to the maximum heat position, the mode button to the floor
position, and the blower switch to high. Using a thermometer, check the air temperature coming from the center floor outlets (Refer to the Temperature
Reference Chart).
If the vehicle meets the minimum floor outlet temperature specification, the vehicle is performing as designed and no further action should be taken. If
the vehicle does not meet the minimum floor outlet temperature specification, continue to the appropriate
Diagnosis/Repair Procedure.
SYMPTOM A - Heater discharge duct temperature drops off at idle engine speeds.
NOTE:
A DROP IN OUTLET AIR TEMPERATURE AT IDLE IS NORMAL. THE FOLLOWING STEPS ARE TO ENSURE THE OUTLET
TEMPERATURE IS AS HIGH AS POSSIBLE.
1.
Verify with the Mopar Diagnostic System (MDS) Scan Tool (DRB II/III) that the engine idle is within specification.
Specifications for vehicles with 1000 miles or more:
2.5L 800 - 1200 RPM
3.0L 610 - 900 RPM
3.3L 575 - 875 RPM
3.8L 575 - 875 RPM
2.
Verify engine coolant temperature.
A)
Does engine temperature gauge read low?
