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Q: I have a 2002 V8 Dodge Durango. For the past five years we have been having issues with the HVAC four-speed blower control. We've replaced the blower motor resistor module five times. Two years ago we did some research and found that maybe the blower motor was bad and was causing the resistor module failures. My dad replaced the motor and put in a new resistor module. Everything ran good for about a year, then the high speed stopped working. Last week all of a sudden none of the speeds worked. I went to an auto parts store and picked up another resistor module and was on my way home when all of a sudden the heat started blowing again. I made another stop but when I started it again no air was coming out. I switched from low to medium and it kicked on. Can you help identify the problem?

A: The repeated resistor module failure and now the intermittent action of the blower motor point to a poor quality, high resistance connection somewhere in the circuit. Start with a careful visual inspection of the connector for the resistor module. Any oxidation, discoloration or evidence of electrical arcing could indicate a poor connection. Make sure the electrical ground connections for the blower circuit are clean and solid.

Next, with the battery disconnected, check continuity to ground for each of the positions of the blower motor switch. Again, a poor contact in the switch could cause this problem. And finally, it's possible the problem is associated with the HVAC control module itself. It might be worth looking for fault codes with a scan tool.

Q: My 2004 V6 Ford Escape has a couple of issues. At times it hesitates to accelerate. I notice it most when I am on an on-ramp and trying to speed up to merge with traffic. The other issue is that the Engine Management Light will turn on sometimes and be on for 5-10 minutes and then go off. At other times it will flash for a while and the engine runs really rough. Also, when I am stopped at a light, sometimes the battery light will flicker faintly. When that happens it runs rougher. Are these problems inter-related?

A: Perhaps. The most serious symptom is the flashing check engine light. This indicates a serious engine management issue that needs service immediately. There should be DTC fault codes stored in the ECM that identify the cause.

– just to name a few.

Q: Your recent article on tire rotation said, "The amount of tire wear 'wastage' due to failure to rotate tires is staggering. In my opinion the method of rotation isn't nearly as important as the need for tire rotation every 6,000-7,500 miles, period." I have a 2006 Cadillac SRX AWD. The front and rear tires are different sizes. How do you rotate them? Or, just leave them alone?

A: Fair question. I should have included information on tire rotation for vehicles with different sized or directional tires.

In your case, the only rotation option would be side to side on the same end of the vehicle. However, if the tires are directional and are designed to rotate only in one direction, you would have to dismount, flip over and remount and rebalance the tires on the wheels in order to rotate them to the opposite side. That would be expensive, time-consuming and could lead to slow rim leaks from the repeated mounting/dismounting.

Cadillac says that "Due to dissimilar front and rear tire sizes, the tire and wheel assemblies cannot be rotated."

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