1997 Honda Civic Engine Overheats unless Cabin Heater is on

WDAWG08

MEMBER
1997 HONDA CIVIC
4 CYL
2WD
AUTOMATIC
197,500 MILES

My engine sensor indicates overheating if I do not have the cabin temperature guage set to warm/hot. It's not necessary for the heat (fan) to actually be on, just that the cold/hot slide selection is toward the hot side. If I move it towards the middle or cold, then the engine heating sensor starts to climb fast.

I had radiator and AC problems fixed at ~175K miles: AC compressor, dryer and expansion valve replaced; New radiator, thermostat & gasket; new AC condensor fan.

3 Replies

KHLOW2008

MECHANIC
41,814 POSTS

Hi wdawg08,

Did you check the coolant level in the radiator?
Did you check if the radiator cooling fans are coming on?

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Friday, January 29th, 2010 AT 1:46 PM

WDAWG08

MEMBER
2 POSTS

Thanks KHLow2008

Did you check the coolant level in the radiator? Yes. Radiator levels were fine; however, the overflow was bone dry. I filled that half way but problem persists.

Did you check if the radiator cooling fans are coming on? Yes, as far as I can tell the fan is working. How can I be sure, will the fan turn on if idling and if so, how long usually?

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Thursday, February 4th, 2010 AT 9:05 AM

KHLOW2008

MECHANIC
41,814 POSTS

If the recovery tank is dry, there must be a leakage somewhere causing the coolant to deplete and air could be trapped in the system. A pressure test would be able to determine where the leak is coming

Remove the radiator cap and run engine with heater turned to maximum. If coolant level drops top up and run till the level does not drop and close the radiator cap. Retest if the overheating occors.

If the AC is not turned on, the cooling fan would only come on when the temperature increases to activate the the fan switch. How long the fan stays on would depend on how fast the radiator cools the coolant to deactive the fan switch.

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Friday, February 5th, 2010 AT 7:07 AM