Q. Have you ever heard of a mechanic being able to charge a "shop supply fee"? Is this legal? A local chain store replaced the brakes on my car, and there was a strange $39 fee on my bill. I questioned the charge and was told that by law they are allowed to charge an 8 percent fee (up to $39) for shop supplies. When I asked what supplies, I didn’t get much of an answer. I have never had this fee charged by any other garage. Is it fair and legal?

A. Some garages will charge a “shop supply” fee as a percentage of the total bill. This fee, is in theory to cover aerosol cleaners, lubricants, hardware and other day-to-day supplies to perform car repairs. Some shops look at these costs as traditional overhead and others prefer to add it to the invoice as a percentage of the repair. In any case, if shop supplies are itemized or not, you the customer are paying for them. These are the costs associated with doing business. In New York, repair shops must charge a $2.50 fee to dispose of tires, they can also charge a reasonable fee to dispose of hazardous waste. Dealers as well as general repair shops may charge for shop supplies (nuts, bolts, solvents, cleaners, etc.) if they itemize the cost of the supplies, charge separately for them on all estimates and repair orders, and disclose the charges in advertisements. As with waste disposal fees, DMV does not approve of pre-printed fees or percentage based fees.

Q. We have a 2006 Pacifica that has gone through three driver’s side low beam headlamps in relatively quick succession. All of the other bulbs in the vehicle are original. The first lasted six months, the next lasted five months, and the most recent lasted three weeks! All the replacement bulbs were Heliolite brand standard halogen bulbs; size H7, purchased from a local shop. The most recent one failed spectacularly, exploding in the headlight enclosure and sending shards of hot glass and strings of plastic (looks like spider web) throughout the enclosure. I am scrupulously careful not to touch the glass of these bulbs with anything during the installation process. Any idea what may be causing this?  I have since replaced the last bulb with a Sylvania bulb and so far so good but it has only been a couple of days.

A. I am not personally familiar with the Heliote brand, however, based on doing a little research on the web, it appears this company manufacturers bulbs from several outside sources in Korea. My experience in the past is that some import bulbs have very poor life (although more than three weeks). You are correct the most common cause of bulb failure is contamination from oil transferred from your skin during installation. Although, in this case, it may not necessarily you, but it also could be a contamination during the assembly process. The second most common problem is poor electrical connections or a problem with the charging system. The computer control module acts as the voltage regulator for the charging system. A technician with a volt-meter should be able to determine if the charging system is operating properly. If everything is okay, it is possible the Sylvania bulb may solve the problem.

Q. I have a 1999 VW Passat. After disconnecting the battery a couple of times to charge it, the check engine light came on, and I started having a problem with a lack of power. I took it to a shop, and they couldn't figure out what the problem is. Can you help me? I found out later that VW recommends not disconnecting the battery.

A. At this point, you need to start with a “scan” of the cars computer system to see what triggered the check engine light. Once you have an engine code it should help with the diagnosis. If you followed Volkswagens procedures for disconnecting the battery, there shouldn’t be a problem. Although, if you are disconnecting the battery to charge it on a regular basis, the vehicle’s charging system, as well as the battery, should be checked.

Q. My Volvo has had a problem with the air conditioner. All the parts seem to work okay, but the air coming out of the dash is warm. I have had two people look at it, and neither can find a problem. One thing that I have noticed is the outside temperature indicator always reads minus 10 degrees. No one I have talked to thinks this temperature indicator is related to the air conditioner not working. Do you think there is a connection?

A. In most cars, there is no connection between the outside temperature indicator and the climate control system. Although in certain model Volvo’s, this is not the case. Recently, I came across a Volvo Cross Country that the climate control would not work until the ambient air temperature sensor was replaced. Once the sensor was replaced, the climate control functioned normally.