Low Heater Performance - Diagnosis/Repair
NO: 24-05-94 Rev. AGROUP: 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?
B) Verify coolant level and absence of air. Low coolant or trapped air will result in erratic heating characteristics. Add 50/50 coolant/water mix if needed.
C) Using the Mopar Diagnostic System (MDS) or the Scan Tool (DRB II/III), verify that all engine systems are functioning as designed. If Diagnostic Trouble Code (DTC) 17 (engine is cold too long) is present, replace the engine coolant thermostat. If other DTC's are present, record them on the repair order for future reference and repair as necessary.
SYMPTOM B - Poor heater system performance resulting in cooler than expected average cabin temperature.
1. Move the temperature control lever all the way to the right to the full heat position. If the temperature control lever does not spring back or springs back less than .080 in. (2 mm) perform the following repair procedure.
A) Carefully remove the instrument panel center bezel that covers the A/C control assembly. Start by opening the ash tray on 1994 models or the glove box door on 1991-1993 models and pulling at one of the corners of the bezel. The bezel is held in place by a clip at each corner.
B) Remove the A/C control attaching screws and pull the A/C control assembly out about 3 in. (7.5 mm) of the instrument panel so the cable attaching point of the temperature control lever at the rear of the A/C control assembly is visible.
C) Lift the blend air door cable eyelet off the upstanding tang of the temperature control lever.
NOTE:
ON 1991-1993 VEHICLES, IT IS NOT NECESSARY TO DISCONNECT THE BLEND AIR CABLE FROM THE TEMPERATURE CONTROL LEVER.
D) Push the eyelet of the cable toward the right until it stops. This moves the blend air door cable to the full cool position.
E) Now push on the eyelet of the cable with a firm and even pressure until the cable moves 1/8 to 1/4 in. (3 to 6 mm) farther to the right.
F) Re-install the blend air door cable eyelet over the upstanding tang of the temperature control lever.
G) Move the temperature control lever to the full heat position. If the control lever has at least .080 in. (2 mm) of spring back from the end of the slot, the clip has been successfully repositioned. If the lever still has less than .080 in. (2 mm) of spring back, repeat steps "c" through "g" until spring back is .080 in. or more.
H) Re-install the A/C control into the instrument panel and torque the attaching screws to 17 in.lbs. (1.9 N-m).
I) Move the temperature control lever to the full cool position and then back to the full heat position. The lever should spring back a minimum of .080 in. (2 mm) from the end of the slot. If the lever springs back in excess of 1/4 in. (6 mm) the temperature control lever should be forcefully pushed to the full heat position to properly position the clip.
J) Re-install the center bezel being sure that all 4 clips are properly engaged.
2. Verify engine coolant temperature.
A) Does engine temperature gauge read low?
B) Verify coolant level and absence of air. Low coolant or trapped air will result in erratic heating characteristics. Add 50/50 coolant/water mix if needed.
C) Using the Mopar Diagnostic System (MDS) or the Scan Tool (DRB II/III) verify that all engine systems are functioning as designed. If Diagnostic Trouble Code (DTC) 17 (engine is cold too long) is present, replace the engine coolant thermostat. If other DTC's are present, record them on the repair order for future reference, and repair as necessary.
3. CAUTION:
Check for hot heater hoses into and out of BOTH the water valve and heater core. Should either component exhibit a cool temperature at the outlet, that component may be blocked or restricted. If a heater core is suspect, it should be replaced with an approved MOPAR replacement ONLY!
SYMPTOM C - Drivers side floor cold, due to lack of direct heater air flow.
PARTS REQUIRED:
1 3849219 Duct, Heat Distribution (for use on 1993 model vehicles only)
1993 Model Vehicle Repair Procedure:
If the vehicle is not equipped with a lower console, skip to step "i".
A) Remove the center instrument panel bezel by carefully unsnapping it.
B) Remove the two 5/16 in. hex head screws just above the cubby hole.
C) Remove the ash receiver/cupholder assembly by depressing the two latching tabs.
D) Remove the two 5/16 in. hex head screws at the rear of the ash receiver/cupholder assembly cavity.
E) Remove the two 5/16 in. hex head screws at the lower right and left sides of the console.
F) Pull the console loose and remove the three Phillips head screws holding the cubby hole to the console assembly. Two are in the front, one is on the rear.
G) Remove the ash tray light.
H) Remove the console.
I) Remove the three 5/16 in. hex head screws holding the floor air distribution duct to the bottom of the heater/air conditioning housing. Remove the duct and discard it.
J) Install revised duct (P/N 3849219) by reversing the steps above.
1994 Model Vehicle Repair Procedure:
A) If so equipped, remove the two screws at the top and the two screws at the bottom of the premium console. Remove the console.
B) Remove the three screws attaching the center floor air duct to the main floor air distribution duct. Remove the center floor air duct.
C) Disconnect the two 25-way connectors from the body control module.
D) Remove the three screws attaching the main floor duct to the climate control unit. Remove the main floor air duct.
E) Modify the main floor air duct by cutting and taping as shown in the illustration.
F) Reinstall by reversing steps "a" through "d".
POLICY:
Reimbursable within the provisions of the warranty.
TIME ALLOWANCE:
SYMPTOM A
Refer to the appropriate Labor Operation Time Schedule Manual for already existing Labor Operation No. as necessary.
SYMPTOM B
Labor Operation No.
24-50-25-91 0.2 Hrs.
SYMPTOM C
Labor Operation No.
24-65-49-90 1993 model vehicles 0.3 Hrs.
1994 model vehicles 0.5 Hrs.
FAILURE CODE:
SYMPTOM A
Refer to the appropriate Labor Operation Time Schedules Manual for already existing Failure Code as necessary.
SYMPTOM B
50 - Improper Adjustment
SYMPTOM C
1993 model vehicles P8 - New Part
1994 model vehicles XX - Service Adjustment