Humming From The Dashboard After A Cold Start (99-031)

HUMMING FROM THE DASHBOARD AFTER A COLD START

TECHNICAL SERVICE BULLETIN

SYMPTOM

A humming noise that lasts 2 or 3 seconds comes from the dashboard area immediately after starting a cold engine with the ambient temperature below 60°. The noise may be mistaken for the ABS pump running.

PROBABLE CAUSE

Friction in the A/C evaporator pressure regulator.

CORRECTIVE ACTION

Replace the A/C evaporator pressure regulator.

PARTS INFORMATION

Evaporator Pressure Regulator Assembly: P/N 80800-SZ3-A01

WARRANTY CLAIM INFORMATION

In warranty:  The normal warranty applies.

Operation Number: 615109

Flat rate time: 1.1 hours

Failed part: 80800-SZ3-A01

Defect Code: 042

Contention code: B07

Template ID: 99-031A

Skill level: Repair Technician

Out of warranty:  Any repair performed after warranty expiration may be eligible for goodwill consideration by the District Technical Manager or your Zone Office. You must request consideration, and get a decision, before starting work.

DIAGNOSIS

1. Turn the ignition switch to ON.
2. Turn off the climate control system.
3. Start the engine.
4. After the engine has run for a few seconds, press the A/C button on the climate control system. Let the engine run for two minutes or longer (especially in cold weather) to make sure the A/C comes on.
   • If you hear a humming noise when the A/C comes on, proceed to REPAIR PROCEDURE.
   • If you do not hear a humming noise, troubleshoot other possible causes for the customer's complaint.
     NOTE: The noise can be intermittent. Select A/C and OFF several times to try to duplicate the symptom.

REPAIR PROCEDURE

1. Use an approved recovery/recycling/charging station to recover the refrigerant from the A/C system.
2. Remove the strut brace.
3. Remove the bolt that mounts the capillary tube and low-side suction line to the pressure regulator.
   Fig 1: Evaporator Pressure Regulator Removal

   
4. Carefully separate the capillary tube from the top of the pressure regulator. Do not bend the capillary tube.
5. Separate the low-side suction line from the pressure regulator. Plug the suction line to prevent contamination from getting into the system.
6. Remove the mounting bolt from the pressure regulator clamp.
7. Remove the bolt mounting the pressure regulator suction line to the evaporator.
8. Remove the pressure regulator and suction line from the car. Take care not to damage the capillary tube.
9. Make a mark across the junction of the pressure regulator and the suction line so you can install the suction line on the new regulator in the same position.
   Fig 2: Reinstall Evaporator Pressure Regulator

   
10. Remove the suction line from the pressure regulator.
11. Place the old and new pressure regulators side-by-side, and mark the new regulator in the same position as the mark on the old regulator.
12. Line up the marks, and then install the suction line on the new pressure regulator.
13. Place the new pressure regulator in the car. Take care when placing the clamp around the capillary tube.
14. Install the suction line onto the evaporator. Tighten the mounting bolt to 9.8 N.m (7.2 lb-ft).
15. Install the clamp bolt. Do not pinch the capillary tube in the clamp.
16. Install the low-side suction line on the top of the pressure regulator.
17. Reconnect the capillary tube to the top of the pressure regulator. Tighten the mounting bolt to 9.8 N.m (7.2 lb-ft).
18. Reinstall the strut brace. Torque the mounting nuts and bolts to 22 N.m (16 lb-ft).
19. Evacuate and recharge the A/C system.