Q: Two years ago my 1994 Cadillac Fleetwood lost most of its cabin heat over the course of the year. I took it to the local mechanic who put in a new heater core and a diverter door solenoid [$450.00]. That didn't solve the problem, so I went to the high tech shop in the next town. He decided the plastic heater box was wrapped and it needed a power flush [3 times][$1300.00]. This didn't solve the problem either so I went to the Cadillac dealer, who replaced the thermostat. When that didn't work he did a power flush, which also didn't work. [$300.00] Now he says it's the cylinder heads, at a cost of $1700.00. But I can't imagine how the heads could stop it from heating since it doesn't loose coolant. As a matter a fact I have told all of them that the hoses going to and coming from the heater core maintain a temperature of about 170+ degrees when the car warms up. I suspect that the dash control may have worn out, and have mentioned it to each of these mechanics. My guess is no one knows how to test this so they keep guessing with my money. Is there a way to bypass the dash control and activate the diverter door to see if I've been right all along?

A: You need to get this car to a mechanic who understands how the HVAC system works. I think the suggestion to replace the cylinder heads to get more heat is downright criminal. I would not patronize the shop that suggested this again.

There’s about a hundred things that might be the problem, from a loose or stuck door in the plenum, to a vacuum leak or bad vacuum motor or vacuum valve to electrical issues with the controls. I’d start by poking my head underneath the dash to see if I could verify the proper movement of any doors in or around the plenum. This may not be trivial, and you might need to remove the ashtray or glovebox to be able to poke around. Once you determine if a door isn’t moving, it should be simple to figure out why.

Q: With over 160,000 miles on my Audi and the braking not what is used to be, I decided to perform a brake system overhaul. I replaced the Brake Calipers, rotors, and pads on all four corners. Bled the brake lines of any air bubbles using a fresh bottle of brake fuild and ensured no leaks upon completion. Prior taking the car for a test drive, the brake pedal felt solid. But upon backing the vehicle out of the garage and down the driveway, there exists a soft feel to the pedal prior the brake pads engaging and slowing the vehicle down. I performed the brake bed-in process per the rotor/pad mfg process. The road test confirmed the soft pedal feel at each stop. However, once engaged, the new brakes stopped the vehicle extremely well. What am I missing in regards to the initial inch or two of soft pedal travel before the brakes fully engage? The pads on all four corners slide well on the caliper carriers. I have performed many brake jobs in the past, and this one has me stumped. Is there something unique to the bleeding process on the Audi that is non-typical?

A: If your vehicle has stability control, there's a procedure in the shop manual that calls for a scan tool to be used during bleeding. The scan tool will actuate valves in the ABS hydraulic unit so air can be purged.

A number of vehicles now call for the use of a scan toll to facilitate bleeding. You may have to have the dealer do this, unless you can find a scan tool to borrow. And that probably will be an Audi-specific tool, not a generic (read inexpensive).

Q: I have a "gently" used 2006 Toyota Tundra and the sprayer units spray only as high as where the wipers lay when they are at "rest". The sprayer units have been replaced twice...are non-adjustable...and Toyota continues to "work" on the problem. I personally think the problem lies in the fact that the standard sprayer design doesn't take into account the difference in the "degrees of slant" of the windshields of the many models they offer (using the same type of sprayer unit for all)!

But here is my question...is there an "adjustable" model of sprayer unit that can be installed in my 2006 Tundra that will do the job right. I have contacted other 2006 Tundra owners and they have the same problem (once I point it out to them) and we have "tested" many truck models from other makers and all of those sprayer units spray right at the eye level position. Even spraying where the wipers rest, Toyota says the sprayers "operate" within their field of vision criteria! Any help you might be able to give would be appreciated!

A: Get an adjustable aftermarket spray nozzle at Pep Boys or Auto Zone or just about any auto parts supplier. Install. Aim. Drive. Wash. Easy, no? Actually, I just looked at the service manual for your truck. It says your washer nozzles are adjustable. Have you actually tried to adjust them?

Q: I tuned up my friend's 2000 Ford Escort. Now when she turns on the heat you get a smell of gasoline. I replaced the fuel filter and checked the connections. Could the heater core be bad? When the heat is off and the temperature is switched to cold you don't get any smell.

A: There is nothing that smells like gasoline in the heater core. You've got a leak in a fuel line or in an evaporative emissions system hose, or solenoid valve that's stuck, or a hundred other things. But it's not the heater core. Fuel or fuel vapor is being sucked into the plenum from inside the engine compartment.

Q: I have a 2005 Volvo XC70. When it was approaching 20,000 miles, I thought I should have the tire rotation done. My husband told me his dealership (BMW) warned him that a car with all-wheel drive should NOT have tire rotation done or it will lose AWD function. I wasn't convinced so I got online to research more. However I couldn't find anything indicate that a car with AWD should not have tire rotation.

A: Every industry source I could find says that AWD cars need regular tire rotation, just like any other vehicle. 20K is actually kind of late. I’d rotate every 10K.

Q: I have a 2002 Dodge full size B-350 Maxiwagon, a 15-passenger Van. They also refer to it as a "Bus". I use it mostly for hunting, fishing & camping trips and love it. You never have to pack anything, just throw it in & slam the door. Nice! Except for one small quirk. In colder weather all the windows fog up. I don't mean just the windshield, I mean ALL the windows, unless I turn the defroster on full blast. Just the defroster! Then they stay respectably clear. If I turn on a multiple setting such as the defroster & lower discharge for the feet or any other setting, everything fogs up within a few short minutes.

Not too hard to deal with in the spring & fall here in Wisconsin, but during the winter it's terribly cold on the feet. Any suggestions? Oh, forgot to mention that the vehicle has a rear heater fan for the rear passengers. Turn it on, turn it off; doesn't make any difference.

A: Are you running in fresh-air or recirculate mode? Fresh-air mode will keep the windows dryer. My only suggestion is a couple of aftermarket fans to move some more air around.