INSUFFICIENT HEAT TO DRIVER'S FLOOR (INST. NEW DESIGN CABLE)

SUBJECT- LACK OF DRIVER'S FLOOR HEAT

MODELS: 1987-1991 G VANS WITH 4.3L (LB4) ENGINES, AIR CONDITIONING (RPO C60) OR BASE HEAT (RPO C41)

Owners of some 1987-91 G vans with 4.3 (LB4) engines and air conditioning (RPO C60) or base heat (RPO C41) may comment that they experience insufficient heat to the driver's floor area. The condition may occur if the temperature control door does not shut completely. This reduces the heated air to the driver's floor area.

To correct this condition, a temperature control cable with improved retention along with an improved floor outlet heat duct has been released. Also, heater warm up may be improved by routing the heater core outlet hose from the heater core to the lower radiator hose.

SERVICE PROCEDURE:

1. Install a new heater control cable (P/N 15685688). Follow the "CONTROL CABLE REPLACEMENT" instructions in section 1A of the appropriate Service Manual.

2. When installed, check the cable adjustment to make sure the door closes fully when the lever is in the full hot position. Follow the "CABLE ADJUSTMENT" instructions in section 1A of the appropriate Service Manual.

3. Remove the driver's left side heater outlet duct. Install a new outlet duct (P/N 15685617) onto the air distributor. Follow the "DISTRIBUTOR AND DEFROSTER DUCT REPLACEMENT" instructions in section 1A of the appropriate Service Manual.

4. Drain the radiator coolant. Cut the lower radiator hose section and install a "T" connector (P/N 15617959) into the lower radiator hose (Figure 1).

CAUTION:

THE RADIATOR CAP SHOULD BE REMOVED FROM A COOL ENGINE ONLY. IF THE RADIATOR CAP IS REMOVED FROM A HOT COOLING SYSTEM, SERIOUS PERSON AL INJURY MAY RESULT.

5. Remove the heater core outlet hose from the heater core to the radiator sidetank. Install a new 3/4 inch hose from the heater core to the "T" connector installed in step 4. Plug off the radiator side opening with a plug (P/N 15544596). Coolant from the heater will now flow as shown in Figure 1.

6. Refill the radiator coolant. Start and warm up the engine. Check for any coolant leaks.

7. If the vehicle is not performing well after the above fixes, then it is possible that the thermo- stat is not regulating correctly. Refer to the "THERMOSTAT DIAGNOSIS" check in section 6B1 of the appropriate Service Manual.

SERVICE PARTS INFORMATION:

Part Number Description Quantity ------ ----------- -------- 15685688 Heater Control Cable 1

15685617 Outlet Duct 1

15617959 "T" Connector 1

155445961 Cap, Heater Water Outlet 1

Procure 3/4 inch Heater Hose As Locally Required

Parts are currently available from GMSPO.

WARRANTY INFORMATION

For vehicles repaired under warranty use:

Labor Operation Description Labor Time --------------- ----------- ---------- T7466 Hose Reroute 0.5 hrs.

Note: Labor Operation is coded to base vehicle warranty coverage in the Warranty System.

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.