My coolant fan only comes on when my ac is on. Whether the car is off or off the fan wont come on unless i press the button for the ac. I checked the fan relay, and it was bad so I replaced it. I checked the ect switch and it tested bad so I replaced it...and yet i'm still having the same issue. And now for some reason my temp gauge is acting all nuts. It'll go full cold all of a sudden and then go right back to normal, or it will go full cold and slowly come back up, or it'll just sit really low. I replaced my thermostat about a year ago so i'm not sure that is bad again or if that would be causing my fan to do this. I tapped the thermostat and didn't notice any difference so I don't think it's sticking. One other thing, is the lower radiator hose supposed to get hot like the top one? Cause mine feels the same way it does when the car isn't on. Any help guys? Thanks!

 

Just tested the thermostat and it's working fine. I'm out of ideas

 

your t-stat is probably stuck open. coolant temp needs to reach a specified temp in order to engage fan operation. if it can't be met, it won't come on.
replace the t-stat with oem..OEM

edit:how did you test the t-stat?

 

I tested it suspended in a thing of water heated by my stove. It started opening right around 160 and was fully open by about 185. It's working properly. I had a thermostat stuck open in the passed and my engine would get warm when i stopped but cool down when i started moving. My car isn't doing that right now. It never seems to overheat until I try and get it inspected and they do the high idle speed test. It's overheated twice during an inspection. I don't know what to check at this point

 

aside from the t-stat, the only other culprit would be an incorrect reading. if it reads cold irratically, it's probably an intermittent open circuit. since i believe honda senders are high resistance cold, low when hot. i think. check the connection at the sender. because of location, they're prone to having oil get in the connector, and/or damage to the wire/insulation.

for your fan issue, try disconnecting the fan switch and jumping across the 2 pin connector. if the fan engages, problem is the switch. if not, check switch ground, and wiring between switch and relay

 

i know this isnt fan related but could cause for temp fluctuations. air in the system. bleed it. i beliive the only thing responsible for fan operation is the ect switch and the fan relay and associated wiring.

 

I know there is no oil in there, I pulled my motor last year and fixed every leak and my motor is still spotless. I'll jump that connector and see what happens. Like I said I bought a new switch and relay yesterday and still nothing.
When it overheated yesterday in the inspection place I might of lost some coolant so having air in there might be why my gauge is reading funny. I'll bleed the system and make sure there isn't any air in there. I'll get back later with the results. Thanks guys

 

I jumped the connecter for the ect switch and the fan came on. If that means the switch is bad that doesn't make any sense, I just got a new one last night. That lower coolant hose that goes to the thermostat is still cool. It's not heating up like the top one, so what i'm thinking is that switch isn't getting hot enough because the thermostat isn't opening and letting hot coolant through it. Now yes I tested the thermostat on my stove last night and it worked, but i don't see why it wouldn't be working in my car. Unless my water pump isn't pumping....

 

Remove the thermostat, remove the rad cap, start car, is coolant moving, if so install a new thermostat, make sure your installing it in the correct direction.

If you do not see coolant moving, replace the water pump.

I can't see it as a water pump problem, you would think you would be overheating all the time. 94

 

well, it wouldn't be crazy to consider a defect out of the box. if the pump weren't pumping you'd be overheating and the fan would be coming on.
the thermostat is also not going to be the problem, since even when it overheats, the fan doesn't engage

 

Coolant is moving I know that. The lower hose got hot this time so I know the coolant is circulating. I just started it and held it at 2500 for about 2 minutes like the inspection places do and it seemed to be all good. The fan never came on, but it wasn't overheating. My gauge sat right below half like it normally does.
Yea since I jumped that connecter and the fan works, that tells me all the wiring for it is good including the grounds. So something about that switch still isn't right. I'm gonna pull it and test it. I know it's brand new but i didn't test it when i put it in last night. I just assumed it would be good, but i'll test it and find out real quick. If it's good then I don't know what to do. I might just leave the connecter jumped and run a switch to the fan so I can turn it on and off whenever I want...I hate to do that, but I'm getting to the point where I don't see any other option

 

Weird its like we have the same car. I have been having the exact same issues it seems.

 

^sucks for both of us then. Welcome to the club.
Ok so I tested the switch and it's good. I'm just gonna go buy a new thermostat and if that doesn't fix it, i'm gonna leave the jumper and wire in a ghetto switch

 

Replaced the thermostat, fan still isn't coming on. It doesn't seen to be overheating though so i'm just gonna leave it as is for now and if I see it wanting to overheat then i'm adding that switch

 

I wonder if the contacts on the plug are spread out too far or something. Did you jump yours with a paper clip or thick wire?

 

If jumping the switch turns on the rad fan then the problem must be the switch, or engine temp. is not reaching "trigger point" or possibly, as mentioned, a plug to switch connection problem.

How did you test the ECT switch?
Did you bleed the coolant system? 94

 

I used a paperclip to jump it and the connecter looks fine. I tested the switch by having it sit right on the top of a pot full of coolant i heated on my stove. I heard a click and then used a volt meter set to that setting that beeps and it beeped, once the switch cooled down it clicked again and then the volt meter didn't beep. So it's working properly. I'm just gonna drive it as is and see what happens

 

something tells me some of you guys just aren't reaching the trigger temp. could be the sender is reading inaccurate even. you did say it was jumping. you have a dvom, check resistance of the sender. first cold. then hot. see if it falls within spec

 

Maybe. I figured out why my temp gauge was acting up. The connector on the sender was loose. I just squeezed it with some pliers and it's fine now. I drove around a lot tonight and the fan never came on, but I didn't see any over heating either. I think i'm just gonna run a switch and turn it on and off when I want. I hate being ghetto like that, and if you guys saw my car you'd see that nothing else is rigged up like that, but I think it's a must this time

 

i had this problem with a TL i used to have. the motor just never got hot enough for the fan to come on. sounds like same for your motor.

 

But when the motor overheats and the needle is almost up to the H...the motor should be hot enough for the fan. I'm gonna wire a switch later today. Thanks for the help guys I appreciate it

 

if thats the case you have a bad ground somewhere.

 

if it were a bad ground, jumping the switch would do nothing.
i would check that sender. confirm that it's actually reading correct

 

Exactly. I trust the sender though cause when it says it's overheating my radiator cap is spraying **** out and I felt my motor so I know it really did overheat.

 

Which brings us back to the coolant isn't flowing well or at all. I don't see how it could be.