Question: I have a 2016 GMC Acadia with LED headlamps and I really like them. I notice a lot of vehicles with one side out and I'm starting to wonder about the reliability and life span. It seems these lights have been offered only the last few years, so I am surprised to see so many out. What is the expected life span and replacement cost?

- A.E., Crystal Lake, Ill.
Answer: What you are most likely seeing are high-intensity discharge and LED conversion kits that are not original equipment. Most of these kits are of poor quality and end up not lasting very long. All conversion kits are illegal, by the way. Recently, we were blinded when a pickup came over a rise with a massive array of LEDs mounted on the front bumper. We beseech better enforcement.

Q: I had a 2006 Ford Fusion and now a 2013 SE model. I've read in several searches that daytime running lights can easily be programmed to be turned on for both model years. However, the Ford dealers that I've checked with say this is not possible. Any suggestions?

- P.F., Chicago
A: If your car is so equipped, you can use the five-way control buttons on the left side of the steering wheel. Enter the information display on the dash and then click through the menu until you get to settings, vehicle, lighting, and then to daytime running lights. Check the box and the DRLs will come on automatically. Or they can be turned on through the headlight switch. This should be covered in your owner's manual.

Q: I own a 2006 Subaru Forester with 70,000 miles. Three years ago I needed a new air conditioner. Now, I am told I need another. The mechanic who installed the second one explained that he sees this problem with cars that are seldom driven. Is this true?

- T.C., Kennett Square
A: It is most likely the air-conditioning compressor is being replaced because its front seal dries out and cracks. It is true that if the A/C is not used regularly, the seal will not get the oil it needs to stay supple. On most vehicles, the compressor runs whenever the driver selects the defroster mode, so it even runs in the winter.

Q: I have a 2004 Saab 9-3 convertible with approximately 66,000 miles on it. Workers at an independent auto chain I go to informed me recently that I do not have to change the timing chain. Over the years I have misplaced my manual and was wondering if they are correct, as I know the consequence of not changing the above mentioned item in a timely fashion. I have deep concern if they are in error.

- B.Y., Chicago
A: The consequences you allude to are damage to the pistons and valves. If the timing belt breaks on what are called interference engines, you are looking at big bucks in repairs. We researched your vehicle on the Gates Corp. timing-belt replacement interval guide. (Gates supplies timing belts to many automobile manufacturers.) Saab 9-3s with a V-6 engine have a belt and the four-bangers have a chain.

Bob Weber is a writer, mechanic, and certified master automobile technician. Send questions along with name and town to Motormouth, Rides, Chicago Tribune, 435 N. Michigan Ave., Fifth Floor, Chicago IL 60611 or