I have noticed a weird thing happening with the automatic climate control. If I set the climate control at the temperature I want (usually 68-72), I notice that, during winter, the car warms up as it should as the engine warms, but then, after about 10 minutes or so of driving, the temperature falls, and I have to keep steadily turning up the temperature dials to maintain a comfortable cabin temp. For example, if I start it out set at 68, it will warm up, level off, and then cool down until I have to turn the dial to about 78 to keep it relatively warm. Similarly, during summer, I would set the temp at, say, 72, but the AC would continue to cool the cabin unless I either turned up the dial or manually worked the fan (requiring constant adjustment). Any thoughts on what might be causing this?