1994 Prelude always had a problem with overheating sometimes. Few months ago at idle the temp would go up then the fans came on. It only overheats at idle or going really slow like in a parking lot. Never overheats when driving. Waterpump started leaking so I replaced it and it doesn't overheat as much anymore. Only after driving for about 30 min in a hot day at a stop light it would climb then go to normal about 10-20 sec later. Then stay at normal for a while, sometimes random. Engine had a stop leak put in before drained most of it out tho. Compression is solid 170 across. I'm gonna flush it, put im new honda thermostat, fresh coolant, and bleed the air with my spill free funnel. But back then when it overheated then the fans came on suspects something is wrong. Coolant temp sensor? Any advice?

 

So u need to test ur fans?

 

Because u are asking slot of questions and have so many variables to ur problem

I'm guessing it's ur radiator. It's clogged or u have a clogg in the line somewhere

 

I just wanted to see if there was anything I can test since the car overheats then the fans come on. I believe there is a fan switch or something like that? I will flush my system and clean it out, new thermo, bleed the air and see if it stops. I can see dried up coolant spots on the top of the rad where the aluminum connects to the plastic but it's not leaking. Maybe it is my rad ;(

 

If the fans not coming on its the sensor, the fan motor, or the fuse.

If you think the motor itself is shot just disconect the clip from the harness. Then jump the fan strait to the battery, it should work then. If it does its a fuse or sensor, if it doesnt its the fan.

I wired a switch to my buddies fan when the sensor went out. Its easy to do, but id suggest trying to fix it first. He has a old saturn and only cost like $10 bucks or so to throw a switch in there with a inline fuse.

 

Sounds like your thermo A switch is bad if the fans comes on only after it starts overheating. Get it from Honda only and it might be a good idea to get a thermostat too if never replaced before. Again its really important to only buy Honda cooling system parts.

 

Where is it located ?

 

Idk If this can be related but before the rad fan use to turn on after the car was shut off now I doesn't even turn on anymore after it's shut off

 

After some poking around the fans work and turn on at the right time. It still overheats at idle even if the fans are on. I had a shop do a water pump and timing belt. It had issues with overheating in the past. When I first got it it had no thermostat, put one in I got at autozone for like 10 bucks. It began to overheat again at idle but cooled once moving. I took out the thermostat and it didn't overheat but then again I never bled the air out of the system properly. After driving with no t stat for a while I decided to buy another aftermarket one but more expensive, It didn't seem to overheat for a while. I'm gonna flush my rad tomorrow since I had my spill free funnel and I squeezed one of my hoses and like dirt came out to the top, I'm like wtf. My cooling system is probably dirty and maybe clogged causing my overheating. Also, my radiator has some dried white stuff where the aluminum meets the plastic on the top, Idk if it's coolant, no loss of coolant tho. I ordered a OEM T Stat. I;m gonna flush again, put new coolant, and bleed the air, if I still get a overheat condition I'm gonna probably replace the radiator. Btw compression test came out 170 PSI on all 4.