Question: What is the best way to use your defroster to clear a foggy windshield.

Hot air or cold air?

Does it depend on the outside temperature?

What about Florida vs. up north?

Everyone we ask has a different idea.

Answer: Air-conditioned air, the warmer the better!

Believe it or not, virtually all modern vehicles engage the air-conditioning compressor when the defrost mode is selected.

The cold evaporator, a cigar-box-sized heat exchanger deep within the instrument panel, wrings moisture out of the ventilated air and also cools it. This dry air is then heated by the heater core and directed to the defroster ducts.

I remember a few decades back when some cars didn't do this automatically and drivers would complain about wimpy defrosting. After being advised to engage the little blue A/C button along with the defroster, they were pleased as punch.

Humid regions will make both air-conditioning and defrosting more difficult.

Q: My serviceman at Toyota wants to service the throttle body on my 2009 Toyota Venza, which has about 60,000 miles on it.

A friend of mine who is a service manager at a GM dealer says that they don't advise doing that, as it wears off the coating on the fuel injectors.

Who is right, and what do you recommend?

A: It's true that some, if not most, throttle bodies are coated with Teflon, and that a harsh cleaner can damage them. For this reason, it's best to use a product that is compatible with coated throttles.

Your friend is correct that some fuel injectors also have Teflon-coated tips, and these should receive the same consideration.

I'm at a loss to understand how a carefully applied and wiped throttle cleaning process would allow much of the cleaner, if any, to reach the fuel-injector tips.

Q: I have an issue with my 2011 Honda Pilot. The auxiliary ports blow the fuse.

My garage charges $25 to change the fuse, so instead, I, a 65-year-old female, bought a box of 15 fuses for $4 and have been changing the fuses myself.

I want to know why the fuse blows almost, not always, every time I plug in my phone to charge it.

A: Have you tried any other plug-in accessories besides your phone charger in this particular port?

The reason I ask is perhaps your cellphone charging device has a loose or unusual terminal at the tip of its plug, and it is accidentally bridging the very close clearance within the charge port's positive and ground tabs.

Also, does the phone charger work OK in a different vehicle? If the charger has an injured cord, this could also lead to a blown fuse.

If you plug in the charger before turning on the key (outlet is not yet active on the Pilot) and this resolves the problem, I'm thinking it's a socket/plug issue.

If it's OK but you find it blows the fuse while moving the cord around, then the charger cord is defective.

Perhaps you can try another charger?

Send questions to Brad Bergholdt at

under-the-hood@earthlink.net.