96-04 Classic S/T Pickup and Utility Rust in Cooling System, Heater Inoperative, Blows Cold Air, Engine Overheats - kw 4.3 99-06-02-012d contaminated contamination coolant GMT325 GMT330 heat L35 LF6

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Some customers may comment that the heater is inoperative, blows cold air, engine may exhibit an overheat condition or the coolant reservoir has rust in it. Vehicles equipped with DEX-COOL® coolant, which may have been operated for extended periods of time with a low coolant level (usually in excess of 32,000 km (20,000 mi), may be susceptible to the formation of a rust-like material in the cooling system.

Follow the instructions in bulletin 99-06-02-012 Technical - Rust in Cooling System, Heater Inoperative, Blows Cold Air, Engine Overheats (Flush Cooling System).

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

(1996-2004 Chevrolet S/T Classic Blazer and S10 Pickup 4.3L) and (1996-2004 GMC S/T Classic Jimmy and Sonoma 4.3L) and (1996-2001 Oldsmobile Bravada 4.3L)

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