Q.  have a 2018 Acura RDX with 29,000 miles on it. When applying the brakes there is a thumping sound from the right front. I checked the tire and there is no visible damage. The brake rotor also looks okay. I still have a warranty on it since it was a certified pre-owned vehicle, what could be wrong? 

A. A thumping sound is typically a lose component or an out of round brake rotor. The issue could be a lose caliper mount, pad moving or even a suspension part. At this point the only thing to do is take the car back to the dealer and demonstrate the problem to get it fixed. Additionally, Acura did issue a revised brake rotor part for this vehicle due to noise concerns. 

 

Q. I have a 2007 Nissan Sentra and replaced compressor and recharged the A/C system correctly. Now when the weather or vehicle is hot inside the air conditioner will not work. The compressor just cycles on and off.  Otherwise, the AC blows cold at about 40 degrees. What could be the cause?  Could it be A/C pressure transducer sensor?

A. At an 85-degree day all I would expect would be the duct temperature to be 55-60 degrees. Typically, rapid compressor cycling is due to a low refrigerant charge. You didn’t say what the pressures are, but I would expect to see 200-220 on the high side and 35-45 on the low side. If the pressure is normal but the switch is reading a low pressure, then it will cycle the compressor. The switch sends a signal to the ECM (computer), and you would also want to check proper voltage just to make sure there isn’t a wiring harness issue. 

Q. I have a 2021 Honda Pilot with just 7500 miles on it. I’m getting a crackling sound coming from the AC/heat vents periodically. The dealer says it’s a loose connection that requires removing the dashboard to replace. Is it worth going through this process and risking future problems with the dashboard or should I just live with it. Your thoughts please.

A. It is a very time-consuming job to completely remove the instrument panel—almost a full day’s work. Since there are no known issues with this that I am aware of (no tech bulletins) my concern would be that after taking it apart and putting it back together it would be worse. I think just having the dealer note the issue and if it gets worse and a bit easier to identify, then have it repaired. 

Q. I have some issues with my 2009 Lexus RX 350 that I bought certified used in 2014 and have several problems. I use the preset buttons when getting in and out of the car to adjust the seat height. For the last three years, the seat has been making an awful groaning sound when I change the positions.  This only happens when it is warm/hot outside—during the winter there is no noise at all. Also, the driver’s window slows down when it’s warm out and sometimes makes a gritty sound.  The passenger mirror doesn’t stay in position where I have left it. Finally, the radio sometime shuts off when I hit a bump (but it never goes on when hitting bumps). Any insight you can provide will be greatly app reciated since I am very comfortable with the rest of the car.

A. From your description it sounds like four separate issues, The power window motor and seat motors (there are three at about $500 each) may be getting near the end of their useful life. The mirror could be worn, have a faulty controller or motor. The radio could be a poor connection to the radio or internally in the display screen. At 13 years old, it is not unusual to see some electrical issues. It is also possible that there is some sort of rust/coorsion issue bridging some of the problems. It would be best to start with a basic check of the electrical system to rule out any basic problems. 

John Paul is AAA Northeast’s Car Doctor. He has over forty years’ experience and is an ASE-certified master technician. He will answer readers’ questions each week. Email your car questions to [email protected]. Follow John on Twitter @johnfpaul and friend him on Facebook, mrjohnfpaul.