A/C Control - Mode Lever Binds After Use of Defroster
89nissan07Classification: HA 89-006 Section: Heater & Air Conditioner System
Reference: TECHNICAL BULLETIN TS89-100
Models: 1988 Maxima
Date: July 20, 1989
MODE LEVER BINDS AFTER USE OF DEFROSTER
APPLIED MODELS: 1988 Maxima (U11)
SERVICE INFORMATION:
On some 1988 Maximas equipped with manually-operated climate control, the defrost control door may bind after several minutes of defroster operation. This occurs when the center ventilator duct walls are incorrectly molded and have become further distorted by heat. This condition will make it difficult to move the mode lever from the defrost position.
Since other factors may cause this incident, it is necessary to verify the complaint by duplicating the operating conditions. The following inspection procedure will help identify the origin of defrost door interference:
Figure 1:
1. Vehicle must be cold (ambient temperature 65~F or below). Set control panel to HIGH BLOWER, HIGH HEAT, A/C OFF, FRESH AIR AND AIR CONTROL LEVER IN DEFROST POSITION.
NOTE: It may not be possible to select Defrost mode due to control cable damage or improper cable routing. If the cable is in this condition, the Defrost mode must be set from the driver's side of the heater unit. Push side link clockwise to full defrost (Figure 1).
2. Start vehicle and allow to run undisturbed with doors and windows closed until full operating temperature is reached (approx. 5 minutes).
3. Open driver's door and slowly move side link counter-clockwise to Full Vent mode - 1 time only. Additional attempts without re-setting pre-test conditions give invalid results.
NOTE: A properly operating side link will move smoothly to Vent position.
^If the side link does move smoothly and set conditions were correct, STOP. Check other areas for the source of the customer's complaint.
^If the side link does not move smoothly to vent position, additional diagnosis information is needed. Proceed to Step # 4.
Figure 2:
4. With vehicle still running, remove defrost door rod from defrost door lever (Figure 2). Using moderately heavy pressure, push defrost door lever rearward (toward back of the vehicle) to the point where Full Defrost has been reached; then, lightly push the same lever toward the front of the vehicle. The lever should move effortlessly. If resistance is felt during the move toward the front of the vehicle, the defrost door is binding on the defrost duct.
REPAIR PROCEDURE:
Use the following repair procedure to correct a misshapen defrost duct partition wall:
1. Record pre-set radio stations.
2. Disconnect negative battery cable.
3. Remove dash assembly.
NOTE: Do not use excessive force. Dash components are made of plastic. Observe the clearance between the windshield and upper dashboard garnish as it is possible to crack the glass during the removal process.
Refer to Page BF-23 in the 1988 Maxima Repair Manual for detailed dashboard removal instructions.
Figure 3:
4. Separate defroster ventilation ductwork from the main ventilation junction box. Place upside down on a workbench (Figure 3).
Figure 4:
NOTE: The rivets which secure the aluminum frame to the top of the defrost duct must be removed by first center-punching, then drilling out (Figure 4). Do not attempt to remove by any type of grinding method, because the plastic ductwork will become warped by the discharged heat.
Figure 5:
5. Measure from the top of the defrost duct flange to the top of the partition walls (Figure 5). Take measurements at points A, B, C, and D.
SPECIFICATION: 7/8 inch.
Figure 6:
Figure 7:
6. If any measurement taken in Step 5 is less than the specification (7/8 inch), remove the necessary amount of material from the defrost duct partition walls to gain the correct clearance/depth (Figure 6 & 7).
Figure 8:
7. Re-mount the aluminum frame retainer to the defrost duct using rivets. For some of the locations, it may be necessary to drill new holes in the ductwork to compensate for the new frame retainer position (Figure 8).
NOTE: Rivet heads should be installed on the inside edge of the ductwork to insure uniform seating and proper mating clearances.
8. Re-install defrost duct on vehicle.
9. Before installing dash, check for proper operation of the defrost door. Apply moderate downward pressure to the flange area of the defrost duct. Simultaneously, operate the air control lever to verify that there is no interference between the defrost door and the defrost duct.
NOTE: At this time, inspect the mode cable and replace it if bent or kinked.
10. Re-install the dash assembly.
CAUTION: After re-assembly, check operation of all the dash controls, lights, and accessories.
11. As a final operational check; first, ensure that the vehicle is cold. Then, set climate control panel as follows: AIR CONTROL LEVER to "Defrost", HIGH BLOWER, HIGH TEMPERATURE, FRESH AIR, A/C OFF. Start vehicle and allow to run undisturbed, with windows and doors closed, until full operating temperature is achieved. Slowly move air control lever to vent position to verify that there is no binding.