How To

How can we improve our vehicle’s cooling abilities?

John Paul, AAA Northeast's Car Doctor, answers a question from a reader dealing with a less-than-ideal air conditioning system.

The Car Doctor answers a question from a reader dealing with a less-than-ideal air conditioning system. AP Photo/Gene J. Puskar, File

By John Paul

June 17, 2025

4 minutes to read

Q. I have a 2009 Toyota Matrix, and my husband has a 2017 Subaru Crosstrek. Both cars do sit in the sun in our driveway, mostly with windshield/dashboard shades. It is surprising to me that my older Toyota has an air conditioner that works great. The Subaru on the other hand is really not great. I think it might help if my husband also covers the hood in the hot weather. The mechanic said it was normal last year when he looked at it. He is a good, honest mechanic. Do you have any suggestions, or is this just the way this model is?

A. Most likely the difference is the size of the evaporator (the part that removes the heat from the cabin). The Matrix uses a slightly larger evaporator than the Subaru, so more heat removal equals more cool air. Also, in 2009, Toyota was not as concerned about miles per gallon and emissions as it is today. The system probably runs longer and uses more energy. Other than that, they both use the same refrigerant and are somewhat similar. As you noted, a foldup windshield screen can help keep the cabin cooler. On very hot days, start the car, put the air conditioner on the MAX setting, and open the doors. You can even open and close the doors (fan motion) to push the hot air out of the car.

Q. I would like your opinion on the 2022 Subaru Forester Touring model before I go for a test drive. I am considering looking at a vehicle that has 27,907 miles (per the on-line listing of the dealership) at a listed price of $26,295. Is this a reliable year and model as far as used Subarus are concerned? You have given me helpful information in the past and would greatly appreciate your opinion.

A. The only issues I have seen or heard of with the 2022 Subaru Forester are that some were plagued with issues with the navigation screens delaminating and some windshields needed replacement due to stress cracks. Pricewise, it looks like it is right on average with others for sale. I would say overall the 2022 Subaru Forrester is a good choice.

Q. My wife and I are both high-mileage drivers that fully expect to own our vehicles until the end of their useful life. We have clocked over 200,000 miles on our last four vehicles, but her current Mercedes GLS has been somewhat disappointing, looking like it will require replacement before 140,000 miles. Due to the amount of time we spend behind the wheel, we trend toward luxury brands or higher trim levels from most vehicle manufacturers. Which vehicles should we be looking for to replace the GLS while maximizing our opportunity to find another 200,000-mile vehicle?

A. It has been my experience that as good as Audi, BMW, and Mercedes Benz vehicles are to drive, once you get over 100,000 miles, they can be problematic. If I were looking for a luxury SUV with dependability, I would look at the Lexus TX (based on the three-row Highlander), or smaller Lexus RX or RX hybrid, Acura MDX, or Genesis GV80. On paper the Mercedes GLS looks better, but as it ages, dependability is where the problems are. With Lexus and Acura, you have very well engineered vehicles that, from my experience, as well as reader comments, easily last 200,000 miles or more. The Genesis GV 80 is solid, reliable, and, yes, it is a gussied up Hyundai, but they did a very good job.

Q. I have a 2024 Nissan Frontier purchased in March 2024. I recently brought it to the dealer for an oil change after one year of driving. My mileage at the time was 2,100 miles. The technician said that because I don’t drive many miles that I should have the oil changed every 6 months. He also stated that if I do not do this, the warranty could become void. I thought that by using synthetic oil that I could go 5,000-10,000 miles between oil changes. What are your thoughts?

A. To maintain the warranty, you need to change the oil and filter every 7,500 miles or six months, whichever comes first. After the warranty expires, you could stretch the oil changes, but I would only do that if you were vigilant about checking the oil. If this were my new truck, I would change the oil twice a year.

Q. I recently purchased a 2022 Buick Enclave. It is in like-new condition, but seems to have one problem. When I start it cold, there is some black smoke and soot on the tail pipe. I had the computer checked and there were no codes. Any thoughts?

A. This is a normal condition with many GM vehicles. This condition is a result of the fuel injector operation. GM uses a dual-pulse injection strategy during engine cold start to reduce the time required to bring the catalytic converter up to operating temperature. It is possible to see some black smoke, soot, rough idle, or even a minimal misfire, during the first minute of operation, and should be considered normal.

John Paul is AAA Northeast’s Car Doctor. He has over 40 years of experience in the automotive business and is an ASE-certified master technician. E-mail your Car Doctor question to [email protected]. Listen to the Car Doctor podcast at johnfpaul.podbean.com.