Q: In April I leased a Cadillac ATS. I run the HVAC system in the “Auto” mode with the temperature set the same on both sides. Last winter with an outside temperature of 50 degrees F. and the system set to 72 degrees on both sides, the blower suddenly went to max speed with cold air from the dash and warm air from the floor vents. The dealer found several fault codes from the HVAC and the radio. After reprogramming the system, the same problem occurred halfway home. After the fourth trip to the dealer, their suggestion was “don’t use the ‘Auto’ mode.” But even if I don’t, I still get strange results at times. Help.

A I have a 2009 Corvette that has exhibited a similarly strange issue. After parking the car with the radio off and the HVAC set to low fan and 68 degrees on both sides, the next time I start the car the radio is on full blast and the HVAC system has defaulted to “Auto.” This happens only randomly.

A very talented technician at a Chevy dealership ran all the necessary diagnostics — it’s all wireless now with nothing to plug into the vehicle — and thinks the issue is actually with the radio. Interesting that they pulled radio codes from your Cadillac.

He pointed to some type of communication or voltage issue resulting in the blaring radio and default HVAC settings. The next step is trying the reprogramming route, which has not been done yet.

In your case — after four tries — I’d suggest to the dealer that he ask for technical help from GM. From my ALLDATA database is GM’s service suggestion — plug in the scan tool, turn on the ignition and “verify every applicable scan tool switch parameter changes when pressing the appropriate switch on the A20 Radio/ HVAC Controls.” If any parameter does not change, replace the A20 Radio/HVAC Controls.

 

Q: My 2008 Audi TT has a convertible soft top. When the top is down I often get an alarm and message “Soft top not secure.” I have stopped, put the top up a little, then back down, but it does not seem to help, as it alarms again. What do I need to do?

 

A: The most likely cause is a problem or misadjustment of the latch. The convertible top latch must be adjusted so the top is 4 mm below the front compartment trim. You’re probably best off taking the car to the dealer for that service.

By the way, to maximize the life expectancy of the convertible top fabric, lower it only before driving — don’t leave it down while parked.

 

Q: I have 198,000 miles on my 2003 Subaru Forester. The dealer wants $875 for routine maintenance in addition to about $800 for brakes. I’m wondering if it’s time to think new. Also, would this be a suitable hand-me-down for a 16-year-old if I put the above money into it?

 

A: Subaru’s maintenance schedule does call for a number of routine services at 200K. These include replacing the air filter, cabin filter, brake fluid, engine coolant, oil/filter, fuel filter, spark plugs and timing belt.

Check your records and skip anything that’s been done in the past 50,000 miles. Then, if you’re serious about giving the car to a teenager, have just the essential services done, such as brakes, oil/filter, air and fuel filters. Because of the cost, I’d suggest skipping the timing belt at this stage of the vehicle’s life. Yes, it could fail and effectively kill the car, but at this mileage and age I don’t think it would be worth the investment.

Since entry-level drivers are more prone to “using up” a car in their early driving experiences, I’d hesitate to do much more at this stage — thus your trusty Suby becomes a disposable car.