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Q: Do I have to use the dealer for repairs and maintenance to keep my warranty in effect?

A: No. As long as you keep records, an independent mechanic, retail chain shop or even you can do routine maintenance and repairs on your vehicle. In fact, the Magnuson-Moss Warranty Act, which is enforced by the Federal Trade Commission, makes it illegal for manufacturers or dealers to claim that your warranty is void or to deny coverage under your warranty simply because someone other than the dealer did the work.

But the law doesn't cover errors. If you or your mechanic replaced a belt improperly and your engine was damaged as a result, the manufacturer or dealer can deny responsibility for fixing the engine under the warranty. However, according to the FTC, the manufacturer or dealer must be able to demonstrate that it was the improper belt replacement — rather than some other defect — that caused the damage to your engine. Either way, the warranty would still be in effect for other parts of your car.

Keep your cool

Q: I have a 2011 minivan. I place a thermometer in the A/C outlet vent in the summer to see how much it's cooling the air. So far, the system has been working great; today the outside temperature was 93 and the thermometer in the A/C vent read 58. But is there a mechanic's rule of thumb that says if/when the temperature difference between inside and outside reaches a certain number, it is time to add a can of refrigerant?

A: There is no such rule of thumb. A tech needs to connect a set of gauges to read the high pressure and low pressure sides of the system to establish the need for more refrigerant. Modern vehicles seldom leak refrigerant unless something was damaged. Keep in mind that outside temperature and humidity do affect the air conditioning performance.

Shifting trends

Q: Do all vehicles (domestic and foreign) come only with floor shifts these days? If not, can one still order a vehicle with a shift on the steering column?

A: Ah, the old "three on the tree" (three-speed transmission with the gear shift lever mounted on the steering column). We have not seen one in years. They were a complex of rods, joints and bell-cranks connected to the two shifter cranks on the side of the tranny. Putting the shifter right into the transmission is way simpler.

Avoiding burnout

Q: With all the high-tech equipment on automobiles' dashboards today, could they not put something in the dashboard to tell us when a brake light is burned out? We have been in that predicament until someone let us know about ours being out.

A: A warning light to alert you that a light bulb is out does exist, but it's available only on higher-end cars.

Bob Weber is a writer, mechanic and ASE-certified Master Automobile Technician. His writing has appeared in automotive trade publications, Consumer Guide and Consumers Digest. Send automotive questions along with name and town to