Background
I've had this car as a project since the head gasket failed. Iv'e been flushing the cooling system a couple times to make sure any residual oil is evacuated and I think I got all I could. After over the head gasket I did NOT change Water Pump as it had just been done 10K miles before w/ timing belt. I also did not change thermostat. I did change the temp sensor and temp sending unit.

Issue
So I've been driving it back and forth to work without issue until the other night I noticed the temp gauge was pushing towards 3/4 the way to H. It normally resides just below 1/2 way. I didn't have time to mess with it until today. I ran the car for a good 15 min with stable temp. Even had the A/C on for a few minutes, and both fans operated to keep temp below danger, but still a little higher than I would like. Turned the A/C off and the temp didn't start dropping. Also the radiator cooling fan does not come on without the A/C on. So that's issue number 1.

After that I stepped on the accelerator to rev up to about 2500rpm, and the temp immediately started dropping quickly. Let off the gas, starts to rise. When driving the car around and moving, no issues with over heating. The problems only arise after driving the car for a bit and then not moving. Unless....I put the car in neutral and rev the motor to higher RPM. It's almost as if at idle RPM water isn't being properly circulated, compounded by the fan not kicking in.
Question
Where should I start? I know the cooling fan works, but only operates when A/C is active. The car overheats when sitting at low idle RPM.

Thanks for any help.

 

Find the fan switch back on the thermostat housing - follow the LOWER radiator hose back towards the firewall. Unplug that fan switch & jumper the wire with a paperclip or something like that.

Key ON, that should make both fans run. This verifies the circuits & relays for the fan.

 

Thanks Jim, I'll try that in the AM.

 

JimBlake,

When wire is jumpered, both fans immediately come on when ignition switched to on. The cooling fan and condenser fan.

 

That would mean the fans/wiring is ok. Since the fans did not turn on, I would look at the temperature switch. When the coolant gets past the half way mark, the switch should read closed. EDIT: Starting in 1998, the accords only had one temperature switch. I would still get this at the dealership.

Here is one other item to check.

When the engine is cold, remove the radiator cap and make sure your radiator is filled to the top with coolant.

Is the thermostat original?

In the future, when your car starts to overheat, turn on the heater full blast to help lower the temperature of the coolant.

 

I have a brand new thermostat and I'm on my way to pick up the switch. I will advise my findings

 

I couldn't get the car to warm up just running in the driveway so I drove a couple miles round trip. When I stopped in the driveway the needle immediately started heading towards Hot. So I plugged in my Scangauge ODB2 reader to watch the temp. Somewhere between 228 and 230 degrees F both fans come on for 5-7 seconds and turn off. This brings temp back between 224-228F, and the cycle repeats.

At those temps the gauge in instrument panel is 3/4 of the way to hot. Does this seem normal? I mean it was about 65 out when I did this. I'm concerned about our coming hot summer with plenty of days pushing 100 degrees.

 

That seems a bit high by the spec's. The switch should close - fans come on - around 196~203F (91~95C).

Did the new switch have any spec's on it? Sometimes the temp spec's are stamped into the brass part of the switch.

These can be a bit of a pain to bleed the air out of the system....can't hurt to double check this and be sure the heat is set to max so the heater core will bleed out.

 

I think the problem was sort of 3 fold. The first, I evidently only ever hand tightened the sensor in the head. Second....there was air in the system. Third, it's not OEM. So now we're turning on between 210 and 213. I can live with that.