QUESTION: When I left my car key in the "on" position by mistake overnight, the battery naturally went dead. When a road assistance person jump-started the car, he showed me the terminals. There was enough green/blue substance to fill a small ice cream cone and he said it was the worst he had ever seen. It took me a long time to finally clean it up. Is it routine for this to happen in a 2010 Ford Fusion or any other make of automobile?

ANSWER: Not routine but not uncommon. The "yuck" buildup on the battery terminals is usually lead sulfate caused by the battery electrolyte — sulfuric acid — reacting with the lead battery post. A poor seal between post and plastic case can lead to this buildup, as can overcharging, loose terminal connections, dirt, moisture and salt.

It’s important to recognize that this buildup is toxic — take care to avoid ingesting, inhaling or having any contact with this corrosion. I’ve used carbonated sugar-free soft drinks and a wire brush to remove the corrosion. Then flush thoroughly with water to dilute and remove all the sulfate. Clean, reassemble and solidly tighten the battery terminals. An anticorrosion spray, paste or even petroleum jelly can help prevent this buildup.

In the case of your vehicle, this buildup may have simply accumulated with no routine battery maintenance. But it might be worth having the charging system tested to make sure the battery is not being overcharged.

Q: We bought a used 2005 Chrysler PT Cruiser. We noticed that when we use the air conditioning, it runs cold until we stop for a red light. Then we get warm/hot air until we’re moving again. Is that a quirk with the Cruisers or is it a problem we need to address?

A: Check the simple things, like the refrigerant state of charge, drive belt, cleanliness of the front of the condenser and radiator. It can be normal for the compressor clutch to cycle the A/C compressor on and off at idle, which will affect the outlet temperature. I don’t think this issue is a quirk of the car; it’s more likely a function of age and lack of maintenance.

Q: The passenger power windows on my 2004 Dodge Ram quad-cab operate properly with the driver’s master switches, but the window switches in the passenger doors do not work. All fuses are good and the driver’s master switch module has been replaced, all to no avail. Suggestions?

A: A careful review of this vehicle’s wiring diagrams in my Alldata database confirms that each passenger power window has two sources of 12-volt power to operate the windows up and down, both controlled by the power window control module/switches in the driver’s door. If the "lockout" button is activated in this module, no power will reach the individual passenger window switches, preventing them from being operated independently. In this mode, only the master switches/module on the driver’s door can operate the windows.

Since the module has been replaced, I’d look for an open circuit in the harness from the module, through the door jamb and into the body harness.

Q: My 2004 Jeep Grand Cherokee with 134,568 miles runs fine, but has one scary glitch. When driving at speeds of 60 to 65 miles per hour, if you take your foot off the gas, the entire car lurches suddenly but slightly to the left. When you put your foot back on the gas, the car lurches suddenly back to the right. It seems like it is caused by torque somehow, but my mechanic doesn’t have a clue.

A: I’d be more suspicious of a significant wheel alignment issue or, more seriously, a loose, worn or broken drivetrain mount or suspension/steering component. A careful inspection of the chassis, suspension and steering is the first step, and if nothing is found, perhaps a four-wheel alignment would help.