Noise or Vibration in Passenger Compartment with A/C On Between 2000-2400 RPM (Replace Heater Outlet Hose)

This bulletin is being revised to add additional procedures and graphics. Please discard Corporate Bulletin Number 01-01-39-005 (Section 01 -- HVAC).

Some customers may comment on a resonating noise or vibration in the passenger compartment with the A/C on between 2000-2400 RPM.

The resonating noise or vibration may be transferred from the water pump through the heater outlet hose into the passenger compartment.

Follow the service procedure below to correct this condition.

1. Disconnect the negative battery cable. Refer to the Battery Negative Cable Disconnect/Connect procedure in the Engine Electrical sub-section of the Service Manual (SI2000 Document ID #527201).
2. Remove the generator cable from the generator and perform the following steps:

•	Reposition the boot in order to expose the stud.

•	Remove the generator cable nut.

•	Remove the generator cable from the stud and position the cable out of the way of the heater outlet hose.

3. Partially drain the cooling system. Refer to the Draining and Filling Cooling System procedure in the Engine Cooling sub-section of the Service Manual (SI2000 Document ID #523104).



4. Using the J 43181, disconnect the heater hoses from the heater core outlet.

•	Install the J 43181 to the heater core pipes.

•	Close the tool around the heater core pipes.

•	Firmly pull the tool into the quick-connect end of the heater hose.

•	Firmly grasp the heater hose. Pull the heater hose forward in order to disengage the hose from the heater core.




5. Remove and discard the heater outlet hose mounting bolt.
6. Remove the heater outlet hose from the water pump.
7. Remove and discard the outlet heater hose.




Important: When installing the convoluted conduit over the new outlet heater hose, position the opening of the conduit so that it faces the front of the vehicle away from the inlet heater hose clamp.

8. Install an approximate 203 mm (8 in) long section of 25 mm (1 in) diameter convoluted conduit (1), P/N 12013948, to the new outlet heater hose, P/N 15079495, and secure the conduit (1) to the hose with two plastic ties (2), P/N 12337820, as shown above.
9. Install the push-on heater hose retainer, P/N 15709297, onto the thermostat stud.
10. Install the new outlet heater hose onto the water pump fitting and the heater core fitting.



11. Route the heater hose behind the generator so that the front of the conduit (3) fits flush against the push on retaining clip (1) and the opening of the conduit (3) faces the front of the vehicle away from the inlet heater hose clamp (2).
12. Install the generator cable to the generator and perform the following steps:

•	Install the generator cable to the stud.

Tighten
Tighten the generator cable nut to 9 N·m (80 lb in).

•	Position the boot to cover the stud.




13. Install a retaining bracket (1), P/N 15045464, to the rear of the generator with a bolt (2), P/N 11515764, as shown above.

Tighten
Tighten the bolt to 50 N·m (37 lb ft).

14. Install a retaining clip (3), P/N 15613086, to the retaining bracket and secure the hoses as shown above.
15. Connect the negative battery cable. Refer to the Battery Negative Cable Disconnect/Connect procedure in the Engine Electrical subsection of the Service Manual (SI2000 Document ID #527201).
16. Fill the cooling system. Refer to the Draining and Filling Cooling System procedure in the Engine Cooling subsection of the Service Manual (SI2000 Document ID #523104).

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: