After a year on the market, Chevrolet slightly changed the Trailblazer for the 2003 model year with the addition of a few new goodies. These changes included an optional V-8 in the EXT model, five more horsepower from the 4.2-liter inline-six, two new exterior colors and a 22-gallon fuel tank.
Cabin Air Filter
Per Chevrolet, the 2003 TrailBlazer does not have a cabin air filter. Some owners, however, have found that the TrailBlazer has the same heating and air-conditioning box as the Silverado, which does have a cabin air filter. These owners find that accessing this box -- under the passenger side of the dashboard -- and removing the bolted-on door allows them to install the cabin air filter set from the Silverado.