1997 GMC Jimmy Owner's Manual - Page 243

Engine FanNoise This vehicle has a clutched engine cooling fan. When the clutch is engaged, the fan spins faster to provide more air to cool the engine. In most everyday driving conditions, the clutch is not engaged. This improves fuel economy and reduces fan noise. Under heavy vehicle loading, trailer towing and/or high outside temperatures, the fan speed increases when the clutch engages. So you may hear an increase i n fan noise. This is normal and should not be mistaken as the transmission slipping or making extra shifts. It is merely the cooling system functioning properly. The fan will slow down when additional cooling is not required and the clutch disengages. You may also hear this fan noise when you start h e engine. It will go away as the fan clutch disengages. If a Tire Goes Flat It's unusual for a tire to "blow out" while you're driving, especially if you maintain your tires properly. If air goes out of a tire, it's muc11 more likely to leak out slowly. But if you should ever have a "blowout." here are a few tips about what to expect and what to do: If a front tire fails, the flat tire will create a drag that pulls the vehicle toward that side. Take your foot off the accelerator pedal and grip the steering wheel firmly. Steer to ~naintain lane position, and then gently brake to a stop well out of the traffic lane. A rear blowout. particularly on a curve, acts much like a skid and may require the same correction you'd use in a skid. I n any rear blowout, remove y o ~ foot from the ~r accelerator pedal. Get the c.ehicle under control by steering the way ~ O Lwant the vehicle to go. It may be I very bumpy and noisy. but you can still steer. Gently brake to a stop -- well off the road if possible. 5-22