REDUCED HEATER SYS. PERFORM. NEW HEATER OUTLET DUCT/PROCED.

VEHICLES AFFECTED: 1988-90 W-CARS

Comments on the above vehicles about heater system performance such as being slow to warm up or inadequate heat may be received from some customers.

If the heater system is operating properly and the engine temperature is in the operating range, the cause of the condition may be reduced air/heat distribution from the heater outlet.

This condition may now be addressed by using the following service parts and procedures.

The parts and procedure for the CHEVROLET LUMINA, OLDSMOBILE CUTLASS and the PONTIAC GRAND PRIX without the performance audio system is as follows:

PARTS

QTY. PART NO. PART NAME ---- -------- ---------- 1 52452131 Heater Outlet Duct 26 in. *06375 3M #4508 Scotchfoam Black Vinyl Foam Tape * Purchase Locally

PROCEDURE:

* Remove the R.H.hush panel, see Fig.3.

* Remove the adapter duct, see Fig. 1.

* Remove the heater outlet duct, see Fig.l.

* Remove the adapter duct, see Fig. 1.

* Remove the two top screws from the module, one on each side. These two screws will be used to mount the new heater outlet duct, see Fig.2.

* Install the 1/8 X 3/4in. foam tape to the grooved mounting surface of the new heater outlet duct, approximately 11 3/4 in. of tape across the top of the outlet duct and 7 in. of tape on each side. Trim off excess tape.

* Install the new heater outlet duct to the module, see Fig.2.

* Install the adapter duct, see Fig.1.

* Cut off a two inch square piece of the R.H. hush panel as indicated in Fig.3. This may be done with a saw blade or a bench grinder.

* Install the R.H.hush panel.

The parts and procedure for the BUICK REGAL is as follow.

PARTS

QTY. PART NO. PART NAME --- --------- ---------

1 52452131 Heater Outlet Duct 26 in. 06375 3M #4508 Scotchfoam Black Vinyl Foam Tape Purchase Locally.

PROCEDURE:

* Remove the R.H hush panel, see Fig.3

* Remove the ash tray retainer, Fig.4, and disconnect the wiring harness from the retainer.

* Remove the adapter duct, see Fig.1.

* Remove the heater outlet duct, see Fig.1.

* Remove the two top screws from the module, one on each side. These two screws will be used to mount the new heater outlet duct, see Fig. 2.

* Install the 1/8 X 3/4in. foam tape to the grooved mounting surface of the new heater outlet duct, approximately 11-3/4 in. across the top of the outlet duct and 7 in. on each side. Trim off the excess tape.

* Install the new heater outlet duct to the module, see Fig.2.

* Install the adapter duct, see Fig. 1.

Using a bench grinder, make a 2 in.long by 3/8 in.deep cutout the front edge of the ash tray retainer, as shown in Fig.4.

* Install the wiring to the retainer and install the ash tray retainer

* Cut off a two inch square piece of the R.H.hush panel as indicated in Fig.3.

* Install the R.H.hush panel.

* Make sure the ash retainer does not interfere with the new heater outlet duct.

The parts and procedure for the PONTIAC GRAND PRIX with the performance audio system is as follow.

PARTS

QTY. PART NO. PART NAME --- --------- ---------- 1 52452131 Heater Outlet Duct 1 20664092 Retainer-Plastic Push In 30 in. 06375 3M Scotchfoam Black Vinyl Foam Tape Purchase Locally

PROCEDURE:

* Remove the R.H.hush panel, see Fig.3.

* Remove the ash tray retainer assembly and the wiring.

* Remove the audio amplifier, see Fig.4.

* Remove the adapter duct, see Fig.1.

* Remove the heater outlet duct, see Fig.1.

* Remove the two top screws from the module, one on each side. These screws will be used to mount the new heater outlet duct, see Fig.2.

* Install the 1/8 X 3/4in. foam tape to the grooved mounting surface of the new heater outlet duct, approximately 11 3/4 in. across the top of the outlet duct and 7 in. on each side. Trim off excess tape.

* Install the new heater outlet duct to the module, see Fig.2.

* Locate the amplifier upper L.H.attachment bracket in the location of the previous R.H. attachment and mark, centerpunch and drill a 1/8 in hole for the new location for the upper R.H.attachment.

* Install the amplifier upper attachments in the new location.

* Bend the lower attachment bracket of the amplifier to the left until the attachment hole is located on the flat surface of the heater outlet duct. Mark and drill a 1/4 in. hole in the outlet duct and secure amplifier attachment to the outlet duct with the plastic push in retainer, see Fig.4.

* The remaining piece of foam tape may be used between the amplifier and the outlet duct to prevent contact and/or rattle.

* Install the adapter duct, see Fig.1.

* Install the ash tray retainer.

NOTICE:

IT MAY BE NECESSARY TO REPOSITION THE WIRING TO ENSURE THAT THE WIRE HARNESS DOES NOT INTERFERE WITH THE AIR FLOW FROM THE HEATER OUTLET.

* Install the R.H.hush panel.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.