I have a 2005 Honda Civic DX. I drove my car for about 10 minutes, with the air conditioning on the highest/coolest level. I then parked my car in direct sunlight for another 10 minutes, and kept the air conditioning on. After about 10 minutes, the front of my car started steaming and coolant started leaking out. I live in California and the temperature was about 85 degrees.

I was a little surprised that it overheated so quickly. Does it sound like there's a possible problem with my car, or is this expected behavior?

2 Answers 2


Yes there is a problem with your cooling system. A car should now overheat in 85 degrees while parked. You will have to inspect your cooling system. Some things to check in order of most likely culprits:

  1. Your cooling fan. (Easy to check this one, once the car gets hot do you see the fan(s) on the back of the radiator turn on.)
  2. If your fluid low or do you have a leak in your system. (Check it everyday and make sure you are not losing fluid)
  3. Is your coolant mixed correctly. (Make sure you aren't filling up the system with just water or just antifreeze. Buy pre-mixed or mix it yourself to the right proportions).
  4. Replace your thermostat. (This is normally a very cheap replacement and most likely need to be replaced).
  5. Check your radiator cap (Make sure it holds pressure, if in doubt they are cheap to replace).
  6. Check the Water Pump, Radiator, Hoses (The hose that brings coolant from the engine to the radiator should be hot)
  • 1
    I had number 2, a leak, as my issue in my Subaru Impreza last year. I also noticed the issue first with air conditioning. Jun 23, 2011 at 3:22
  • Thanks for your detailed response. I took it to the Honda dealership for service, and they said there was a leak in my radiator. They replaced my radiator and it now seems to work fine.
    – Alec
    Jun 24, 2011 at 2:21
  • I will mention that the Hondas I've seen use some tiny little radiators. Not much margin for error, if you've got anything wrong at all with the cooling system, you're probably headed for overheating pretty quick. Can't be neglected the same way one might be able to get away with in some other cars. Jun 18, 2012 at 13:45

If the car only overheats at idle the most likely cause is the cooling fan is not working. Crank up the car and let it get to operating temperature. The cooling fan should turn on somewhere between 185 - 200 degrees. Turning on the AC should make the fan (at least one of them if you have more than one) turn on immediately.

All of the other things jzd mentioned in his answer are valid as well, but I would add to check to make sure nothing (leaves, grass, etc.) is blocking airflow through the radiator.

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