PolkaSauce

Not sure if this is posted elsewhere, so my apologies if it is, looking for a little insight.
I've got a 2003 Crv Rt4wd that I purchased back in February. Recently, I discovered that the cooling fan fuse was blown when my V overheated in a parking lot in a hot day. Later on(in a cooler climate) I put in a new fuse, got the engine back up to operating temps, and nothing switched on. Turned on the AC and the entire front end started shaking, and the fuse blew again. Turns out the cooling fan had a large chunk of blade missing. I'm guessing the PO never cared to fix it, and the car never got hot enough for me to notice. Ok, I replaced the cooling fan, and the fuse. Back up to operating temps. Reving engine(1500rpms intermittently, nothing crazy), for at least half an hour, gets to just under half, nothing switches on, but temp never goes over half. Switch the AC on and both fans spin up just fine. I've poked around the internet, and most answers I see say check the ects. But I've seen diagrams that note there is a radiator fan switch located towards the bottom of the radiator somewhere (can't find an explanation, just crude diagrams), only no one seems to mention it when this issue is brought up on forums or youtube or anywhere else I've looked. The only reason I don't suspect the ects is because the day the V overheated, when the engine got really hot, and the condenser fan was running, without the AC on. I believe I've read somewhere that when the car reaches a high enough temp, the condenser fan will also kick in as a back up to assist the cooling fan in less than favorable conditions. All the relays and fuses are good. Both fans work. Just the cooling fan is not kicking in when it should. As of now I'm resorting to running the AC intermittently to cool the engine in stop and go traffic on hot days. The ram air force while driving at almost any speed that isn't dead stop seems to take care of the rest. The engine never really gets hotter than just below or at half, with the exception of the one overheating incident.

Am I crazy, or are there two switches controlling the engine cooling fan? Just looking for some insight before I tear the plastics off and the air box out trying to find the issue. Thanks in advance!

Also, I've seen lots of posts about similar issues, so if and when I resolve mine, I will be sure to post it up for anyone else experiencing the same thing.

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tech8

See this other thread regarding the operation of the fans:

https://honda-tech.com/forums/honda-...g-fan-3308694/

PolkaSauce

I'll try the paper clip trick when I get home tonight. Figers crossed that's all it is, or maybe even just a loose connection altogether. Thanks!

PolkaSauce

Jumped the wire harness, and both fans did turn on. Gonna try and throw a new switch in there tomorrow and see if that does the trick. Thanks again!

PolkaSauce

UPDATE:
So I went and bought another cooling fan switch. Swapped it in, burped the coolant system as per Honda owners manual. Fans still didn't turn on. Jumped the ects, fans still didn't turn on. Left the ects jumped, and jumped the cooling fan switch, fans turned on. At this point I'm thinking I bought a defective switch. But out of curiosity, I plugged the old switch into the harness and heated it up with a lighter(ects still jumped) after about a minute of flame, the fans turned on. So I plugged back in the ects, tried it again. Guess what, fans turned on. So I know all relays, fuses, and switches are good as the system turned on with no jumping. Only heating up the old cooling fan switch. Both hoses on the radiator get hot so I know the coolant is flowing (the switch also gets hot to the touch where it mates to the radiator). AC blows cold. Heater blows hot, so I don't suspect the thermostat. Is there something I'm missing here?

Ca-Renegade

I Was having the same issue recently, I kept having to drive with the heater on blast when it was hot out. I did all the same steps as you, end result I finally killed my laziness and removed plastic covers. Radiator was cracked up in driver side top. Couple notes- The K series engines are reverse flow for the coolant, which is why thermostat is on the bottom hose. OEM thermostat is a must- the aftermarket tolerances for temp aren't the same. Also i bought a Lyles funnel to bleed out system ( these engines are known to get air locked.) Good luck bud!

PolkaSauce

Thanks for the info Renegade. I took off all the plastics, checked the radiator, and found no cracks or leaks. Got fed up and bought an OEM cooling fan switch, tossed it on, burped the radiator again. Still. Not. Turning. On. Only when the AC is on. I went through all the relays and fuses again, just to double check. They're all good. I know the fan is supposed to come on around 280° or something like that, and then engine is plenty hot Not overheating, but a little under half way on the gauge. Tested the old(newish) switch by applying heat to it while plugged into the harness, and the system turns on just like the other one. I'm at my wit's end here. I'll try swapping out the etc just to be sure, but I really don't feel that's the case if the system comes on with no jumping of the harness. Getting ready to just ghetto rig a switch on the dash to activate the fan at this point.

PolkaSauce

Okay, forget that last post. Out of sheer desperation, I unplugged the battery for 10 minutes to reset the pcm, thinking maybe the computer was having an issue with the temperature reading, as jumping the harness would set off engine codes. Plugged the battery back in, ran the car for about 10 mins, and voila! The fans kicked on. So lesson learned. Buy OEM parts, and reset the computer.