LOW HEATER OUTPUT 6.2 DIESEL

A low heater output condition may be experienced on diesel equipped vehicles.

With the new 6.2L diesel, and as is true with other diesels, heater temperature is not as high as with a gasoline engine. This is especially true at idle due to the lean fuel mixture. A more rapid cool down occurs in the diesel from high speeds to idle speed.

A low radiator coolant level will also cause a "no heat from heater" condition. Should a customer comment be received of a "no or low heater output" the following should be performed prior to any major diagnostic checks.

1. Check the coolant level in the radiator (check when cool) to assure adequate coolant. Top off if necessary. Check overflow bottle also.

2. Check the routings of the heater hoses to assure free flow of coolant (no kinks, not pinched under jack handle, etc.).

3. Advise the owner that during extended idle a forced idle of 1,000 RPM (approximate) will result in a higher heater output.

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.