Expert Advice

Smells Like a Bad Switch
Q: I have a 2003 Chevy Silverado. The air-conditioning had a burning smell, and, after I noticed it, I lost the high-speed mode. The smell disappeared after a week or so, but it came back and I lost the next-highest speed. I thought it was the switch, so I replaced the whole control face but it still only has the three speeds left. Is there a relay or something else that's failed? If so, how do I get to it?

A: The 2003 Chevy truck may either have a manual or automatic HVAC (heating, ventilation and air-conditioning) system. The manual system operates blower operation through a control module (which you've already replaced) and a blower-motor resistor assembly. When the highest fan speed is selected, full voltage travels through the blower relay directly to the blower motor. When lower speeds are used, the voltage passes through select resistor coils, which lower the voltage and therefore reduce the speed of the blower motor. The automatic system does basically the same thing with the use of solid-state components. In this case, a blower-motor control processor replaces the blower-motor resistor assembly. Going by the burning odor, I'd guess you have the manual system, and the problem lies in the resistor assembly, which houses the resistor coils, and the blower-motor relay. Also, the blower motor itself may be drawing excessive current and burning these components up, one by one. Have the system diagnosed by a competent technician before replacing any additional parts.

Guarding Against Guards
Q: I am thinking of installing a brush guard or grilleguard on my 2001 Dodge Durango. I don't do any off-roading, but there are large numbers of deer in our area. Would the damage from hitting a deer at highway speed actually be increased by the presence of a brush guard? Also, could it make damage worse from typical auto-to-auto accidents? My concern is specifically with low speed fender-benders, since the front bumpers would no longer be the first point of contact.

A: I'm sure NHTSA or the Insurance Institute for Highway Safety would provide an accurate response if either performed crash testing before and after grilleguard installation. Unfortunately, that's not the case. And forget about the deer-impact analysis. An engineer from a well-known truck-accessory manufacturer confirms there's been no collision testing involved with the development of its various types of grilleguards--it would be hard, therefore, to say they provide added protection. For the most part, these products are cosmetic truck enhancements with limited shielding ability, unless they're mounted directly to the frame and reinforced. If you like the look, go for it; however, if you're looking for vehicle protection, you might have to keep looking.