Hi,

I have a 2004 Honda Accord EX (4 cylinder) with automatic transmission.

Lately the car has been running extremely hot; firstly the heat needle is way up at the red H, secondly the air conditioning is not even able to blow cold air, presumably because the engine is so hot.

I checked the coolant two days ago and it was very low so I refilled it with about 50/50 antifreeze/water combination. The car was fine the day after that. The next day, however, it went back to being extremely hot. I checked the coolant levels again- they're still good; it does not seem like any coolant has leaked.

What could be wrong??
Thanks!!

 

Do the radiator fans work?
Crank the car, pop the hood, turn the AC on full blast. Both fans should come on.

 

Ok I tried that, both fans do come on.

 

First thing that comes to my mind is a thermostat sticking closed.
Hmm...I'm not sure how to check a tstat on a 2004....
I'll try looking around to see if I can find a test for you.

 

feel all the hoses to see if they are all the same heat

 

Thermostat is really easy to reach in 2003+ (4-cyl). Lower hose is right there between the engine & radiator, T-stat is right there. If the T-stat is stuck closed, the lower hose would be cool.

I'll try to remember to check the Helm book - see later post...

 

Update on this:

Somehow it seemed that after I left my car overnight, it took almost a gallon of antifreeze. My mechanic told me that it might have had a pocket of air in the coolant tank that went away after the tank fully cooled down (originally I only waited an hour after driving it before filling it). In any case now that the coolant is (truly!) full, it seems to run just fine. Thanks for the advice/help!

 

Wow, that didn't happen when I changed antifreeze in my 2003. Good warning for peope to look for.

After filling, I normally squeeze the hoses & listen. Air pockets make a sloshing sound so then I know I have to do something to deal with it.

 

had you done any work on the car the first time that you checked coolant and it was low ??? if not , you might have a leak somewhere , i can see that when you filled it up there was an air pocket but i keep on wondering why ws it low enough the first time when you checked it to make it overheat ???

 

Yes, check for leakage. Maybe pressurize it cold so you can find the leak easier. For now, when you check your antifreeze levels, check inside the radiator too. Not just the overflow reservoir.

I remembered to look up the fan control stuff.

In 2003 & 2004 the fan switch is in the lower radiator tank, #10. It's to the left side, on the back-side of the radiator.

Check that the wires are OK to that switch. Unplug it & jumper the wires with a paperclip. Key on, that should make both fans run.

Incidentally, in 2005 & 2006, the fan control sensor is in the same location, but it is wired into the ECU. And it seems to be a proportional temperature sensor, not a simple switch. The ECU then controls the fan, so you can't test it by jumpering the wire.