2005 Honda Civic

A friend has a 2005 Honda Civic with approximately 120,000 miles that she just bought the end of 2013. The car was kept immaculate by the previous owner. This week as she was driving, she said the temperature needle suddenly went all the way to H. Earlier in the day, she had noticed the A/C was not consistently cool but didn’t think much of it as there were no other problems with the car. When the temp needle suddenly went to H, she shut off the a/c and before she could pull over the temp needle went back to normal. She checked the coolant level which was very low and she took it to the dealer who ran multiple tests including checking the thermostat, cylinder compression tests, etc but they could find nothing wrong. I keep telling her there is a reason it did that and that coolant doesn’t just disappear and that I think she should take it back. Any suggestions?

Did she see any steam coming out of the engine?

You’re right that coolant doesn’t just disappear. It leaks out of holes in the radiator hoses, or through a bad radiator cap, or through a bad head gasket.

Check the oil. If it’s milky-looking (dark brown to black and opaque) and/or foamy, then you have coolant leaking into the oil and have a bad head gasket.

If the oil looks fine, then it’s time to get it up to temperature and then examine all the hoses while the engine is running. See any steam escaping? Replace whatever it’s escaping from.

I’ll go with the head gasket.

I presume the coolant has been topped off. If not, that’s the first thing to do. You are right, the source of the coolant escaping from the system needs to be found. But it might not be leaking much, so if that’s the case just checking the level every day or every week until the leak is found is a work-a-round. The coolant level has to be checked by removing the radiator cap, not simply looking at the level in the plastic expansion tank. The coolant should be just below the rim of the radiator cap. Safety note: As it says in the owner’s manual probably, only remove the radiator cap when the engine is completely cold.

There are usually some fans in the engine compartment that are supposed to turn on when the AC is on. If those fans didn’t come on it could cause the AC to blow warm and could cause the engine to overheat possibly. Engine fans are supposed to come on when the coolant gets too hot also, AC on or not. Ask the shop to verify that all the engine fan functions are working properly.

A faulty AC compressor that was not spinning freely could contribute to these symptoms so that’s worth checking.

Whenever an engine overheats, in an emergency some engine cooling can be effected by turning the passenger compartment heater to max and the heater fan to max. Open the windows if it gets too hot. That methods uses the mini-radiator under the dashboard to help cool the engine.

Front wheel drive cars are highly dependent on the radiator fan and the condenser fan

They really need them to “keep their cool”

I’ve seen many FWD cars run hot very quickly when one of the fans failed

This happened to my brother’s Mazda and my sister-in-law’s Honda

Both cars ran extremely hot because one of the electric fans failed

In both cases, replacing the faulty fan resolved the issue

My condenser was dirty on my Honda and caused it to overheat. Once I hosed it off it stopped overheating. Try that first and make sure its got coolant. Cheap and easy. Also make sure to get the air bubbles out of the radiator.

My cousin had his Accord overheat sporadically because one of the fans stopped working.
Lucky for him it was just a loose connector.