Q. There is a problem with the heat in my 1999 Ford Crown Victoria. When driving to Florida this year the heater stopped working. I stopped at a Ford dealer and they thought it was a motor in the heater. At that time I chose not to repair the problem. Now the heater blows full blast out of the dash vents. What is wrong? By the way, I consider this car to be the best car I have ever owned.

A. The heater and air conditioner system on your car is controlled by a series of vacuum motors. As these cars start to age, the vacuum lines begin to leak and the vacuum motors can wear out. A technician will need to spend some time under the dash looking for vacuum leaks or binding/stuck vent doors.

What’s a safe car?

Q. I’m in the market for a new car. My biggest concern is safety; what should I buy?

A. With over 350 cars on the market today, and a car being such a personal decision, this a very difficult question to answer. A car that I like and that fits my lifestyle may not be a good match for you. Most people need to consider a budget, fuel economy, comfort and style. Since safety is a priority, start with looking at cars rated five stars by National Highway Safety Administration. Their Web site, www.safercar.gov, will provide a good start to your search. Also look at the Insurance Institute for Highway Safety’s Web site, www.iihs.org. Both of these Web sites will allow you to choose the safest car in a specific class. Once you have a list of cars, you’ll need to go on a sufficiently long road test to see if you like driving the vehicle. I hear too often from readers who buy a car based on recommendations from well-meaning friends and end up living with a car they hate.

No cabin air filter

Q. I have a 1998 Lincoln Town Car and my wife has a 1999 Mercury Grand Marquis. Is there a cabin air filter that needs to be changed on either one? If so, where is it located? I’d like to change the air filter myself.

— Bob M., Cranston

A. The cabin air filter is one of the most overlooked filters in cars today. One of the reasons is that not every vehicle has one, as is the case of your two cars, neither has one. Using my car as an example, the filter is $22.95 and it is located behind the glove compartment and can be installed in under 15 minutes.

Check the coolant sensor

Q. When my ’97 Cadillac Seville sits overnight it will take four to five attempts at cranking before it will start. Once started, the car runs and starts throughout the day without delay problems. There are no codes that are showing. Furthermore, the engine has relatively new spark plugs. The fuel pump pressure is fine. In trying to isolate the problem, I recently tried hand choking at the throttle after overnight. In each instance the engine starts immediately. Is it possible that the coolant sensor is faulty? If so, is it difficult to get at to replace?

A. It certainly makes sense to check the coolant sensor. The sensor is located on the right cylinder head on the flywheel-end of the engine. The part is about $30.00, and with draining the coolant, it will take about two hours to replace. I would also be very critical of the fuel pressure. You need to see 48 to 55 pounds of pressure for the car to start properly.

Is old spare tire safe?

Q. I have a 2002 Jeep Grand Cherokee Laredo and need to buy new tires. I have a full-size spare that came new with the car and has never been used. Although it has never been used, it is really seven years old. Is it safe to buy three tires and use this as a fourth, or should I just spring for the whole set?

A. Although some major tire manufacturers as well as the Rubber Manufacturers Association don’t acknowledge age as a reason not to put a tire in service, there are a couple of other considerations. Although there is little scientific evidence to suggest tires age, consider that the tire design has been changed just enough for the spare not match the latest design. In addition, the British Rubber Manufacturers Association suggests replacing tires once they are five years old. My experience is that one never gets a flat tire at a convenient time! If it were my Jeep, I would buy four new tires and keep the never-used spare where it is.

projocars@projo.com