Accord (98) overheating problem

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98 Honda Accord EX - 6 cyl
This has happened about three times the past year, two recently, but with summer and traffic jams, anticipate it more often. Car runs fine, but when stopped in traffic jams, after about 10-15 minutes, the car will start to overheat while standing or idling in traffic. Once I get moving and the air flow starts up, the temperature quickly drops. Is this is a minor or major do it yourself fix up. Some have suggested a fan clutch, but it may seem to be the fan motor or sensor from what little I have been able to read on it.

Any suggestions would be helpful. Trying to avoid a dealer fix, currently the car has about 100k on it, and is due to go in for the timing belt replacment, tuneup, and a major maintenance overhaul - spelled $$$$. Just paid it off, and have replaced brakes and front struts the past two months - more $$$$.


posted by  Chuck7701

Hi, sounds like something as simple as a blown fuse, the temp. will obviously drop as you pick up speed as the air is acting as the fan would (although it doesn't work on all cars). I'd check the cooling fan fuse, if not try the switch..trial and error my friend :thumbs:

posted by  Cliffy

Okay, first stay away from the person who told you it was the fan clutch because it doesn't even have one and advice like that you don't need. From your description there is little doubt in my mind that you problem is fan related, because the temp stays normal as long as you are moving and have air flow through the radiator. The first thing I want you to do is start the car and turn on the A/C. If the fans kick on you have eliminated the fans, relay and wiring as the source of your problem and are most likely looking at a coolant tempeature sensor. If they don't kick on then we're back to the fans or power supply.

By the way, before you get too deep into this, have you checked the fuse?

posted by  vwhobo

lol....we must have been typing at the same time vwhobo...Your explanation is better thorough so I dont suppose it matters :thumbs:

posted by  Cliffy

Fuse(s) OK.

Both fans kick on when started, AC on etc. as suggested. Did notice that the fans cycle on and off repeatedly, when it was cold and normal running temp. The kick in for a minute or so, then stop, and 10-15 seconds later, kick back on again. The cycle continues over repeatedly. This seems odd.

Thanks for your help so far.

posted by  Chuck7701

Some cars do, do that Chuck, it's not at all strange

posted by  Cliffy

Good, now that we know this we can eliminate the fans, relay, wiring and power source as your problem. I think if you do the previous test again you'll find you A/C compresser is also cycling just like the fans and I'll assume it's a cool morning so the system won't be working on a 100% duty cycle. That's normal ops.

This pretty much narrows your problem to the coolant temperature sensor or the PCM. There are three things I want you to do now.

1. First and foremost beg, borrow or steal a manual for your car. This will help you to find component locations.
2. With the engine running, find and disconnect the coolant temp sensor. It's very important you have the right sensor for this to work. The temperature sending unit is in close proximity and looks about the same. When you disconnect the CTS the fans should come on within a few seconds. If they don't, replace the CTS and your problem will almost certainly (99% for sure) be cured.
3. If disconecting the CTS makes no difference the next thing you need is a scan by a competent tech who understands what the codes and datastream mean. The reason this step is here is because basically this is about as far as we can go online, and I sure don't want to tell you to swap the PCM.

posted by  vwhobo


Thanks for the great information and resolution to my problem. Did purchase a manual, found the sensor, and the problem was the sensor was NOT CONNECTED for some reason. Recalling the times it overheated, the AC was not on at those times. Manual says that that the fans will automatically cut on anytime the AC is on, regardless of the state of the sensor. That was the confusing part of the diagnosis, why it only happened intermittently.

Thanks again for the advice.

PS, the service rep at Honda commented that someone knew what they were talking about when I inquired about your proposed troubleshooting or resolution.

posted by  Chuck7701

vwhobo is pretty good - he has done this kind of thing for quite a few years.

posted by  tbaxleyjr

I tried all the above also, replaced the CTS. Originally, fan would only run when car was off and key was not inserted. NOw, the fan will turn on only while engine is off. It will also run while key is in ignition, but will turn off when you turn the key to RUN position (With car off). Any help? Your tips were on point.

posted by  awill91594

one fan is controlled by the cts and relay,the other fan by the a/c circuit.
since it is hot out when the a/c is on...second fan works.if you run defrost mode and a/c is on a different cycle,the #2 fan cycles.

posted by  the lobster

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