Non-working radiator fan in 96' Accord.
May 13, 2015 4:41 PM   Subscribe

Are a non-working radiator fan and non-working AC system related? I'll list more in depth what I've checked so far below.

Originally noticed the fan not working while trying to add freon to a non-working AC system(blasts warm air). I noticed that there appears to be enough freon so that made me wonder if the fan not coming on had something to do with it not producing cold air. The A/C condenser fan comes on when the A/C button is pressed but not the radiator fan. The compressor also activates when I press the A/C button. My engine began getting really hot and the radiator fan never came on. The radiator fan fuses are fine and the radiator fan relay is fine because I swapped it and the exact same voltage power window relay and the windows still worked. I also used a code scanner and no codes except for my catalytic converter popped up, which I've known about for a while. Does not having a code for my radiator temperature sensor/switch completely rule out an issue with it? I've read that you can plug the fan motor directly to the battery but I want to hold off on buying the wire for that until I rule out other issues. So if my fuses are fine, the relay is fine, and I'm not getting a code for the sensor, other than the fan motor itself, what else could be the issue? Any advice on the fan/ AC issue and whether or not they're related would be much appreciated. Thanks in advance guys!
posted by to Technology (8 answers total)
Are a non-working radiator fan and non-working AC system related?

No. Well... not related but possibly affecting it a bit to some extent *maybe*. If your car is stationary, then a non-working fan can prevent the air conditioner radiator from receiving enough air over it to cool the charge flow. But if the air con is not cool when you are driving (anything above 30 mph sustained for 2 minutes plus, say) then the fan is irrelevant. It is likely to be completely unrelated, to be honest, as you'd not get warm air (just 'not as cooled' air is the fan was the affecting issue).

So rest assured that there is no real correlation between the two as long as air flow is a given, so driving down the road should give you that answer. The air con has some other issue, and I don't do enough air con things to be able to help you with that, but the fan is a distraction to your A/C issues.

My engine began getting really hot and the radiator fan never came on.
As for the fan, and assuming all your other problem solving is correct, then it is either the coolant sensor that triggers the fan, or the fan itself. I'd jump 12V to the fan and see if it spins to validate the fan motor, and then start looking at the coolant switch (check through your wiring diagram). If 12V spins the fan (just use two wires from the battery + and -, no need to get fancy) then the triggering system is at fault (either the coolant sensor/sender or a wiring issue most likely).
posted by Brockles at 5:11 PM on May 13, 2015 [1 favorite]

I had a '94 accord and replaced both fans and the radiator itself. My memory is not extremely distinct but I know i did all of those things around the same time, for the same reasons. My guess is that, even if the AC fan is working, the radiator isn't getting cooled enough (because the larger radiator fan isn't working) so your AC might feel like it's not working. I'd definitely replace everything at once, if you can, because it's not fun work.
posted by destructive cactus at 5:13 PM on May 13, 2015 [1 favorite]

Thermostat tells the fan to come on, and helps with the AC. Thermostat is a relatively cheap solution, if you catch it in time, if you don't, then you warp the engine head as I did.
posted by Oyéah at 9:16 PM on May 13, 2015 [1 favorite]

Test the impedance on the fan motor to see if the windings are hosed, then disconnect the fan and wire it up to some jumper cables and tap them to the battery and see if it spins.

Last time i dealt with this problem and all the troubleshooting you've done so far was fine, it was actually a bit odd. Heat had destroyed the insulation where the wiring went in to the motor, and it had slowly split away at the strands until there was a tiny enough amount that it just melted off from resistance. This sucked because until a very close visual inspection, i was seriously stumped because the motor itself was fine as well.

(i stripped the wire, shoved it into the motor, and gorilla glued it in place. Don't do this, i was a stupid teenager... that did work for years though)
posted by emptythought at 10:22 PM on May 13, 2015 [1 favorite]

Thermostat tells the fan to come on, and helps with the AC.

The thermostat has nothing at all to do with the fan trigger or the AC. The thermostat just closes the water routing to the radiator partially during warm up of the engine (ie first 5 minutes or so) to allow it to warm up faster. It is completely independent of the AC system. A thermostat that is stuck shut can cause your engine to overheat (because water is not routed to the radiator to cool the engine), but it would have no bearing at all on whether the fan came on or the AC was effective. The issues are unrelated.

The fan trigger is an electrical switch in the coolant system that turns on the fan above a certain level.
posted by Brockles at 7:05 AM on May 14, 2015 [1 favorite]

Response by poster: Thanks for your responses everyone I greatly appreciate it.

Brockles-is there a specific type of wire I need to get to performs the battery-to-fan test? The video made it look like they were miniature jumper cables with little alligator clamps?
posted by at 7:52 AM on May 14, 2015

AC and engine cooling are on separate circuits.

You need a Chilton manual for your car ASAP. It would have the troubleshooting procedures. Follow brockle's advice. He's good, but if you don't have a manual to go along that shows you exactly what's what it's not going to help much as you waste time trying this and that. Chilton manuals are like $30, definitely worth it if you plan to do a lot more self-diagnosis in the future.
posted by kschang at 9:57 AM on May 14, 2015

is there a specific type of wire I need to get to performs the battery-to-fan test?

Nope. It's harder to screw it up and short something out if you have fancy clips and the like but any 12 or 10 gauge wire ($2-4 a small roll? Autozone or similar) is fine. Because it is hard to hold four ends of two wires in the right places (earth to plug plus live to plug), I tend to put the earth wire under the battery terminal to clamp it and hold the free end. Then wedge the end of the live wire into the (in this case) fan plug (maybe using a toothpick). Then I can touch the live wire to the battery and touch the earth end to the fan plug without getting fat fingers in the way (two hands in one plug) and without anything that might short out flapping about anywhere. But I'm usually tall enough with long arms that this is relatively easy for me.

But that's just for a quick bodge to verify the motor. It's ... not exactly best practice. You can just wire to earth and positive and just make sure you don't short out the live end against the other wire or the body, but that's a bit iffier if you're not too handy.
posted by Brockles at 11:27 AM on May 14, 2015

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