Heater - Slow Warm Up/Inadequate Performance at Idle

FILE IN SECTION: 1 - HVAC

BULLETIN NO.: 43-11-12

DATE: May, 1995

SUBJECT:
Slow Heater Warm-Up or Inadequate Heater Performance During Engine Idle (Replace Floor Air Outlet and Flush Heater Core)

MODELS:
1992-93 Buick Skylark
1992-93 Oldsmobile Achieva
1992-93 Pontiac Grand Am
with 2.3L Engine (VIN D - RPO LD2, VIN 3 - RPO L4O), 3.3L Engine (VIN N - RPO LG7)

This bulletin cancels and supersedes Corporate Bulletin Number 331102
(Group Reference I - HVAC).

CONDITION

Some owners may comment on a condition where the heater air is slow to warm up or the heater outlet air during idle is not warm enough.

CAUSE

Some vehicles may exhibit a condition where the air flow from the floor air outlet does not provide enough circulation to the front of the passenger compartment. A new floor air outlet has been designed to redirect air flow to the front seat and to distribute air more evenly across the floor.

Also, some engine core sand may have accumulated in the heater core, resulting in reduced coolant flow. A backflush of the heater core ONLY will remove this debris.

To further assist vehicles equipped with VIN D and 3 engines, a new 205°F (96°C) thermostat has been developed. For vehicles equipped with VIN D and 3 engines, Federal Emissions ONLY, a new EPROM has been calibrated to increase cold weather idle boost. This elevated idle increases water temperature and flow through the heater core, thus improving performance.

CORRECTION

Vehicles equipped with VIN D and 3 engines with Federal Emissions:

1. Replace thermostat.

2. Replace floor air outlet.

3. Replace EPROM.

4. Flush heater core.

Vehicles equipped with VIN D and 3 engines with California Emissions:

1. Replace floor air outlet.

2. Flush heater core.

Vehicles equipped with VIN N engine, either California or Federal Emissions:

1. Replace floor air outlet.

2. Flush heater core.

SERVICE PROCEDURE

Heater core flush -

1. Disconnect heater hoses from heater core.

2. Backflush heater core.

3. Reconnect heater hoses.

For thermostat, floor air outlet, and EPROM service procedures, refer to the appropriate Service Manual.

PARTS INFORMATION

Important:
The following kit numbers contain the parts needed to perform this procedure. The EPROM numbers are for reference only.

Kit numbers:

1992 L40 Federal Emissions 22646937
1992 LD2 Federal Emissions 22646938
1993 L40 Federal Emissions 22646939
1993 LD2 Federal Emissions 22646940
1992-93 L40/LD2 California Emissions 22646941
1992-93 LG7 All Emissions 22646941

EPROM Part Numbers:

Model/ Trans/ Broadcast Part
Year Division Engine VIN Emission Code Scan I.D. Number

1992 2,3,4 N L40/3AMT Federal BNUP 5563 16215577
1992 2,3,4 N LD2/3AMT Federal BNUR 5573 16215579
1993 2,3,4 N L40/3AMT Federal BNUS 5583 16215581
1993 2,3,4 N LD2/3AMT Federal BNUT 5593 16215584

Parts are currently available from GMSPO.

WARRANTY INFORMATION

For vehicles repaired under warranty, use:

Labor Operation Labor Time

D2813 (Thermostat, floor air outlet, 1.6 hrs (2.3L Engines
EPROM, heater core flush) W/Federal Emissions)

D2813 (Thermostat, floor air outlet, 1.4 hrs (2.3L Engines
heater core flush) W/California Emissions)

D2813 (Floor air outlet, 1.0 hr
heater core flush) (All 3.3L engines)