Having my first technical issue with my 3,5 years old Hyundai Accent.

During past years the engine coolant temperature gauge was - after warming up - always pointing to the middle of the scale (inbetween the two small dots). This was not depending on vehicle speed or outside temperature.

Since a few weeks I experience following problem:

The gauge is showing higher temperatures, between the middle of the scale and the red zone, but never reaches red zone.

This happens only at higher speeds, over 100 km/h (60 mph). When the problem happened, the temperature was about 30 degrees C (86 degrees F).

It only happens, when AC is switched on!

Even with AC ON, the gauge is pointing to the middle when the speed is at about or below 90km/h (50 mph), so I only experience this on highway.

While having AC off, the coolant is not heating at all = gauge pointing to middle at very high sppeds and uphill - 140 km/h (82 mph). :)


I did following troubleshooting/checks already:
- cleaned the both radiators from insecpts, washed.
- both fans works OK.
- fan belt of coolant pump is OK.
- coolant level is full, and NOT loosing any coolant.
- oil level also OK.

Could you please advice two things please:
- what can be causing above issue?
- how critical is it to run engine with slightly high coolant temperature (over middle of scale, but below red zone)?

Thanks, Attila

you could try flushing and adding new cooland....could also be a couple of other things.

-Air Trapped in the system
-Water pump or one of the passages could be slightly clogged
-belt on the pump or maybe the pumps pully is slipping
-could be a bad thermostat

and maybe a couple other things.

I would not constantly run above normaltemperature....the reason why my wife got a accent was because we were driving in her old car and her temp kept going up...we kept shutting down the engine and it never went in red....but there was a crack in the block which ruined the whole engine. it was a bad water pump.

Years ago that was a symptom of a lower coolant hose, suction, collapsing do to high speed. That hose had metal spring in it to prevent it from happening.

-tr

A quick way to remove air from the system to to jack up the front of the car or park on an inclined driveway and run the car with the radiator cap off. Don't take the cap off if you have driven the car recently because you will get burned by steam. After the car has been warmed up fill the radiator up to the top with distilled water or a coolant mixture.

If that doesn't help you might have a bad water pump that can't flow enough at higher speeds. Also check your radiator hoses for pressure.

Thanks for the tips and ideas - I decided to have it checked at hyundai official service, rather than dealing with it by my own. This wednesday I will know more:)

Kind wishes, attila

Try looking at the engine coolant temp senor. May be defective. Ac is turning on fans but is the actual cooling system (coolant) is turning on the fans at correct temperature.