See if both fans turn on when your engine is running and you turn on the a/c.

 

Take a look at the radiator fins at the bottom(around the cooling fans) if they are missing, gooey, and/or detached from the radiator tubes it is time for a new radiator. The fins work like the fins on an air cooled engine.

 

I checked both suggestion from above and they are all NORMAL working condition..

here is what i notice.
start the car, let it warm up 10mins..go for a drive with a/c on and the needle started to climb slowly to H..but i would have to be driving for about 5-6mins before it happen..

turn off A/C and the needle go back down to normal op. temp..my mechanic said he let the car run with ac on for 25mins and no sign of over heating..then he let it idle at 2k rpm for 15mins with ac on and still no sign of needle rising to hot..

but why does it happen on the road and not at park??

 

One thing that's different is that your engine is making way more power (and more waste heat) when it's actually pulling the load of driving. Probably need very little throttle to hold the engine at 2000 rpm with no load.

Another thing is maybe the motion of the car is doing something to the wiring for the temperature sender. Sender for the temperature gauge has only one wire so it's grounded through the car. Maybe a flaky ground somewhere? Flaky ground made worse when you run AC because the compressor clutch similarly has only one wire...?

Does the engine move excessively (bad engine mounts)?
Can you make the gauge misbehave by wiggling it's wire?

 

Hi hondadriver84,

I am the original poster who had the overheating engine and the fans coming on and staying on after engine shutdown. Like you, I relpaced the thermostat and looked at the radiator fins but didn't see any problems. But the problem was in fact with radiator fins bit I simply didn't look close enough.

How did you actually check the radiator fins on your car? You cannot see if the radiator fins are partially blocked by looking down between the a/c condensor and the radiator (its only about 0.5 inch gap and doesn't allow you to look through fins, only across them. Looking at the back of the radiator through the cooling fans is a waste of time as well. The back of my radiator was very clean but the front was a mess. (see the attached photos).

You need to release the upper radiator guides allowing the radiator, with the fans to be pushed rearward slightly while sitting in lower supports. This should allow you to take an adequate look at the front of the radiator to check to see if the radiator has any discoloured patches on it. If so it will indicate an external blocakge. Its only a 10 minute job.




Regards

Terry

 

Terry,
thanks for the pictures..i will have to check it again when it stop raining..so after you replace the rad. everything is ok again?? no more needle bouncing?

JimBlake,
i will check the ground wire and surround ground wires also..i put in brand new battery and brand new 12V+ and Ground wire, all 4Gauge wire..battery terminal look very clean..will check other surrounding location..i will try to see if i can make the needle jump when wiggle with sender's ground wire..

thanks guys

 

I didn't need to replace the radiator. I just removed it from the car and took it to a radiator specialist who used a combination of washing and compressed air to remove the debris from the fins. If you have access to compressed air you can do this yourself but you must be very careful with the fins. They are very thin aluminium and squash very easily. In my case I placed the radiator in a tub of detergent water (it was actually the bath and boy did I get some grief), and let it soak for a couple of days. I then tried compressed air to blow out the debris (being careful not to blow too close to the fins or else they will be damaged). However, my compressor was pretty useless and that's why I eventually took it to the rad specialist to finish the job properly.

This fixed the problem. Once the engine warms up, the temparature gauge remains rock steady no matter what the drving conditions, engine load or outside air temp. As you can see from the photos, a good 60 or 70 percent of the radiator was blocked, so it was amazing the engine was being cooled at all. So there is obviously an excess of cooling availability in the radiator design which allows for effective cooling when the weather gets hotter, you are towing a heavy trailer and the air con is on! But at some point as the fins get progressively more blocked with insects, dust and debris, the cooling system will become overloaded. In that case, overheating when the aircon is on would be a quite possible outcome, particularly if this is in conjunction with warmer weather or towing a trailer.

Finally, if you have replaced the thermostat, checked that your engine coolant is in good order (no rust or heavy particle contamination) then an internal blockage (or water pump impellor corrosion) is less likely to be the cause. Only after you are completely satisfied that radiator fins are entirely clear, should you then start looking at electrical or electronic problems.

Hope this all helps and best of luck hondadriver84.


Terry

 

UPDATE!!!
problem SOLVED thanks to Terry and everyone on here for all the helps and suggestion on diagnostic..
we end up replacing the radiator, brand new super stat T-stat and t-stat gasket, clean out throttle body with tb cleaner..clean fast air idle valve located under the TB..clean out IACV with carb cleaner..re-clean EGR, soaking it in B12 carb cleaner, this stuff works awesome...used carb cleaner and re-clean EGR port to clear, spray over the port, wipe and let dried...

now everything is PERFECT, better then before..at first start up after refilling coolant, the engine would stall out atleast 5x..turn it on, it'll choke and want to die then it die..after several tried it finally stayed on once the t-stat started to open up..coolant flow very hot and once t-stat fully open the temp needle didn't budge anywhere near 1/2 mark..heat is HOT, a/c is COLD..best part is NO OVERHEATING what so ever...even after an 45mins test drive with a/c on, off..heat on, off..needle sit perfectly where it's suppose to be..

so believe it or not, replacing the radiator fix it all for us..no special radiator shop around this small town to get it clean..so best options is to replace it..new rad. cap, new 50/50 prestone coolant..everything is GOOD now..car drive a lot smoother then before..next come the hard part, oil in spark plug tube..need to change the inner gasket under the camshaft..changed VC gasket kit already and didn't help.

thank you all

 

Glad to hear you got it fixed! Alot of us folks do not realize that the condensor and radiator gets clogged over time,even though it "looks" clean.

These parts need alot of airflow to do their job correctly.Over time,they get blocked with dirt,bugs and etc.

It is almost the same as cleaning the a/c unit outside the house...wash it with a water hose and clean the fins out.Then it starts cooling way better and no overheat!



You can do the same with your cars...if it runs hot,remove the radiator and wash the fins out with a water hose or compressed air.Do the same with the a/c condensor in the car.Dont have to remove that,but wash it and blast the dirt outta there.Makes a world of a difference.