Latest Reader Q&A (Oct. 5, 2017)

Here are the latest reader questions, along with my replies:

Jonathan asks: I recently wrecked my Pontiac so now I’m in search of a new car, one preferably under 10,000. Any advice on good used cars?

My Reply: The good news is there are lots of options. The bad news is, there are lots of options! As I get into in my book about car buying (see here) the first step is to narrow down the field to specific types of cars you’re interested in (e.g., sedan or compact crossover SUV?) and then winnow that down some more based on your budget and your preferences as far as brand and so on. If you give me some specifics in re the above, I’d be happy to offer some thoughts.

In general, though: With about $10k to spend, you could probably buy something like a 3-5 year-old Corolla in very good shape, with about 50,000 or so miles on it. Not an exciting car, but a good, solid transportation appliance.

Steve asks: Does the cold setting on the car’s window defroster use the car’s air conditioning system? How does it work? I know very little about HVAC. I have observed that if the defroster is set on cold and runs for a while, if you switch the air flow button to the vent position, cool air continues to come out. It’s not cold the way it would be if the A/C was turned on, but it is noticeably cooler. I notice my gas mileage doesn’t take a hit in the summer time either, so I am inferring that some other method is used. Is this just my imagination about not using the car’s A/C, or is some other cooling method used?

My reply: If you have manual AC (not climate control) the AC compressor will only cycle on when you push the “AC on” button. The temperature setting is irrelevant. Cooler air will still usually flow, though – assuming you turned the knob in that direction vs. hot – and especially if the AC system was on.

The system is just venting more outside air vs. heated (by engine coolant, via the heater core) air into the passenger compartment. And you are getting some residual cooling effect as air passes over the parts of the AC system that cool the incoming air.

If, on the other hand, you have climate control AC, the compressor will automatically cycle on whenever the temperature setting demands it or when the defroster is selected. It tends to come on more often and of course, you have less control (ironic, given the name). The main advantage of climate control is that it maintains a more precise temp setting (e.g., 70 degrees) whereas with manual, you’re simply selecting “warmer” or “cooler” or “cold” or “hot.”

PS: The AC system also dehumidifies the air, which is very useful as far as helping to clear condensation off the windshield.

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Got a question about cars – or anything else? Click on the “ask Eric” link and send ’em in!

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