Q: My husband and I have an ongoing dispute. Does a car cool off more quickly if one opens the windows while waiting for the A/C to kick in? I say that any breeze or airflow is better than no airflow. (However, I guess there is a little airflow from the vents before the A/C kicks in, but it doesn't seem to cool the car as quickly as fresh air.) Or, as my husband avers, is it better to melt onto the leather seats for the five minutes before the A/C cools us off because opening the windows and letting in the hot outside air will make the A/C less efficient? I'm obviously right, right?
A: Chill. You are not obviously right, but you are partially right. Running the air conditioning draws outside air into the cabin, so opening the windows a crack allows the hot air to be replaced by cooler air. But, better yet, setting the HVAC system to recirculate, or max A/C, re-cools the air that already has been cooled.
Q: My wife has a 2014 Jeep Wrangler (manual transmission) approaching 70,000 miles. She takes good care of it but recently has had some issues. She was driving on the highway and it convulsed into jerky movements. It wouldn't accelerate past 30.
We got it to our mechanic. He scanned the computer for codes and saw that timing readings were reading correctly. He cleared the codes, test drove it multiple times with no problems, and none of the codes have returned. The Jeep seems to be running fine. We're stumped.
A: Stumped? The mechanic can't find anything wrong. Most people are stumped if the technician fails.
Q: I recently bought a 2002 Honda from a service station. They said it was in working condition and would stand behind the transmission and engine for three months. The problem is that the air conditioner works when the car is moving, but when we are idling, it blows hot air. I brought it back and showed them your column about the rubber tube being clogged. They checked it, but the car still is doing the same thing. Am I facing a bigger problem?
A: A clogged drain hose gradually reduces the A/C efficiency, but once the evaporator coil icing condition melts, the A/C is restored. I think the problem is a bit more complicated. The A/C condenser, which sits in front of the radiator, might be restricted from bugs and leaves, or the electric fan could be malfunctioning. In either case, air from driving down the road could be sufficient to cool both the condenser and radiator adequately. Not so when you stop.
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 firstname.lastname@example.org.