Heres my problem(s) Hi ambient temps lately. Living in Phoenix so go figure.
At freeway speed with AC on no problem. But after exiting freeway after approx 40 min drive. at slow speeds the engine temp will start to rise eventually boiling the coolant in the radiator..
Here's what I've already tried.
Pressure tested cooling system to 13 psi= good
New T-stat Genune Honda.
Purged cooling sys. No air in there.
I can idle the car all day with air on or off and it wont overheat.
No AC on, 2 fans will kick on and cycle keeping temps normal.
Now heres the kicker.
With the AC on both fans will run.
When AC is off with High water temp indicated(and water puking out of overflow) both cooling fans will run.
Jumper switch A. Key On(at the thermostat housing) both fans run.
Jumper switch B. Key On or Off (under the distributor in the head) Niether fan runs.
So both relays are good since both fans run.
Is it just the timer/controller thats bad? And does anyone have a illustration of it where its located.
TIA
Sweaty in Phoenix

 

So, reading your post, the fans both appear to be working when the engine is overheating? So, that would lead me to believe they are both ok? Youre sure that they are both actually moving the correct amount of air? Ie, spinning fast enough, ive seen these fans where they will run, just not run very efficient. Also, when is the last time the coolant was flushed? How old is the radiator? Did you pressure test you radiator cap?

Also, do you have an OBD2 reader, that shows live data? If so, what is the running temp of the engine...when normal driving, overheating etc?

 

I'll get back with you. Got in it this am and the check engine light was on.
So it stayed at home. I'll get a cap today and check temps thru the OBDII.
I was thinking it could be a fan speed issue.
But will one fan kick on before the other? Or do both fans always run at the same time?
And I don't recall any fan ever running on after engine is off

 

Sounds like either a blockage(possibly radiator) or your water pump fins are worn.

 

H2O pump was changed last winter . Genuine Honda parts used.
Put on a new cap and changed the fan switch as cheap insurance.Drove it in to work today with no issues.
I'll have to drive it over the weekend to see if I cured it.

 

You said your fans are always working, even when overheating so the fan switch shouldn't be an issue unless your observation is wrong. I suppose the cap could be bad but you would normally have issues with your reservoir because of the cap seals not working.

Please update this if your issues have been resolved.

 

Ok updating this after a weekend off.
Replaced Rad cap and as a "since I have it" I replaced the fan switch at the thermostat.
ran a trip of just a few miles.
At speeds of 40+ no cooling issues. Car ran fine and didn't overheat.
But once my speed slowed to 20-25 mph Temp indication started to climb.
Got it home and popped the hood.
AC on, Fans running, Coolant and bubbles being pushed into overflow res. temp indicating hot almost to the red. Turned AC off fans quit running (temp was still indicating hot). switched AC on fans started back up.
Let it idle a bit and needle started to come back down.
Shut it off and parked it in disgust.
Ordered a couple of new fans from Rockauto and will update after they are in.

 

Also get a Denso radiator. I think your radiator fins are blocked or it's blocked internally. Fans are only bad if they stop. If they are running they can't really be the issue. It's possible they can start making noise, but as long as they are moving they aren't the issue.

Edit: Actually, seeing as how your reservoir is filling up, I would bet it's corroded internally.

Also, check if your condenser fins are blocked by debris.

 

Roger that. I'll be draining and inspecting it this weekend
What significant about the Denso radiator? I see Denso's and Valeo Design on Rokauto.

 

Denso is OEM

 

Just me but are you sure there isn't air trapped in the cooling system from the recent work

 

Updating for future searches.
Lost again, system was properly bled,no air in there.

Finally got back to looking at it after having it sit for 2 weeks
The few tubes I could see thru the rad cap opening didnt look too bad, though there was what looks like grains of sand stuck in a few of the tubes.
Ordered a new radiator from RA. and changes the fans today.
I'll update after new rad is in and running