Click and Clack talk cars - By Tom and Ray Magliozzi
AC use fine, even if stopped
Q: My husband and I recently purchased a new car. My husband refuses to run the air conditioning in heavy stop-and-go traffic or if we are sitting in the parked car. When I ask him what the reason is, he says that since the compressor for the air conditioning is belt-driven, if there is no airflow into the engine, the car will overheat. So I'm wondering why I see everyone else sitting in their nice, cool cars with the windows up, but their cars aren't overheating. He has been this way with all of his vehicles. We have a vacation coming up with a 12-hour drive. I'm worried about long, HOT construction delays. Is he right - should I continue to silently melt in 90-degree weather? Or can we turn on the darn AC? Katie
Ray: Katie, we feel for you. We really do. The reason you see everyone else sitting in their nice, cool cars is because they're not married to your stubborn husband.
Tom: He's being overly cautious. Far too cautious. For at least three decades now, all cars have come equipped with electric cooling fans. When the car isn't moving and there's no wind being pushed through the front grille, an electric fan now comes on, independent of the engine, and makes its own breeze for the radiator.
Ray: That's why cars can sit in traffic, even with the AC on, on very hot days, and still not overheat.
Tom: In fact, most cars have a second cooling fan, or a higher speed for the cooling fan, that kicks in automatically whenever the air conditioner is turned on, just to provide extra cooling under hot conditions.
Ray: Now, there is a limit to a cooling fan's effectiveness. It never will provide as much cooling air as you would get when driving 65 mph on the highway. So if you're stuck in traffic for a long time, and it's 120 degrees out, an engine still can overheat. But those are highly unusual conditions.
Tom: So the bottom line is that you're suffering needlessly. Here's what you should do: Suggest that your husband try leaving the AC on during your upcoming vacation.
Ray: Right. Just leave it on, whether you're stopped or moving. As long as the "HOT" warning light on the dashboard doesn't come on, that means the car is fine. And unless you're in bumper-to-bumper traffic in Phoenix during a horrendous heat wave, or the cooling system malfunctions, that light's never going to come on.
Forgotten clamp? $2,800
Q: I took my vehicle in to a local mechanic shop for a timing belt replacement. After the repair, I drove approximately 75 miles, and the transmission burned up. We had the car towed to AAMCO. The AAMCO owner said the cause of the transmission failure was that the previous mechanic had forgotten to remove a clamp from one of the two coolant lines that run to the transmission, resulting in the transmission overheating and then a $2,800 repair bill for a rebuilt transmission. The original mechanic says he never clamped off any lines when he replaced the timing belt. What do you think? Would lines have been clamped? Marilyn
Ray: They certainly could have been.
Tom: For certain cars, you DO have to remove the radiator to change the timing belt. And if you remove the radiator, you would clamp off the transmission cooler lines so you don't spill transmission fluid all over your shoes, or the shop floor.
Ray: Cars with longitudinally mounted engines (mounted the long way, front to back) require you to remove the radiator to get to the timing belt. Those include lots of VWs and Audis, all Subarus, lots of small SUVs and pickups, and many other vehicles.
Tom: So if you have a longitudinally mounted engine, the AAMCO guy is absolutely right. If you clamp off the lines and then forget to remove the clamps when you're done, you prevent the transmission fluid from getting cooled. And within 100 miles, that can raise the temperature of the transmission enough to ruin it.
Ray: You're lucky that you have an eyewitness who will testify that when your car was towed in, the clamp was still there!
Tom: So, start by getting a written statement from the AAMCO guy describing exactly what he found. Take it back to your original mechanic, along with the repair bill, AND his clamp. Ask him if he'd like to write you a check now, or if he'd rather write you one later, with the court costs added in, because small claims court is your next step.
Ray: Keep in mind that if your car has 195,000 miles on it, the court might not make the shop pay the whole cost of a new transmission. But you'll win in court, Marilyn. As long as you don't lose that clamp.
King Features Syndicate