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Odd Radiator Fan Behavior And Idle Issue

Radiator fan behavior idle problem

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#1
blondgirl921

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This issue is one in the same.

My AC fan (on the radiator) comes on when the AC button is pressed, like it's supposed to. When I drive around or it's a really hot day, when I'm in park or just stopped at a light the car begins to idle roughly. The RPMs drop below 500 and every once in a while the car will shut off. While diagnosing this problem I realized that it's idling rough because the AC fan is turning on and then off again. When the fan is just steady, I don't have any issues with the idle. I can feel when the fan turns on and off while I'm driving, but it's most noticeable when idle. My mechanic just recently repaired the fan terminals and replaced the plug.

My secondary problem (that I feel is related) when the AC button is not pressed, only one fan comes on (normal). BUT when the engine gets too hot (200 degrees or so), the AC fan should come on, correct? The problem is that it doesn't, then the engine will over heat. If I keep the AC button on, both fans are on and keeps the engine at the right temp.....but then we have my initial problem when I'm idling.

This has been an issue for some time and my mechanic is totally stumped. He had the car for a week, worked on it every day to try different things but couldn't figure it out. I'm hoping someone here may have a solution (or a good push in the right direction).

#2
Tiberianx

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Could be a problem with your relays. Not sure if you have 3 fan relays on your car

#3
blondgirl921

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I have 3. should I replace them all? or just the one for the AC fan?

#4
Tiberianx

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It's hard to say because I don't exactly know what kind of fuses/relays you have under your fuse boxes.
I only see 2 fan relays in the Haynes manual for your year

Would it be alright if you take a picture of the fuses and it's locations?

It could be a bad ECT, test the resistance of the sensor, should be about 2200-2700 ohms at 68'F and 290-350 ohms at 180'F. Don't take it out during a hot engine because it'll depressurized and spray hot coolant all over you

#5
blondgirl921

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Ok. Here's a pic of the fuse box and the guide on the inside of the cover....

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#6
Tiberianx

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Looks like somebody's tempering with the 2 fan fuses (pink ones)

Probably gonna need someone's advise here that knows how this works, because I am honestly not sure myself either.

#7
blondgirl921

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My mechanic had it for a week. He said he tested a bunch of things....it's possible he broke them? I don't know.

#8
4thgenceli

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Those pink things are not the fan fuses. The fan fuses are the two 30amp fuses in the middle side by side.

The air con relay under that cover engages/dis-engages the magnetic clutch on the AC compressor.

The 3 relays just outside of that fuse box are the ones you're looking for. I can't recall offhand which is which (I can find out quick once I look at a wiring schematic though).

With the A/C off, the cooling fan (closest to the battery) will turn on and off when the engine coolant reaches a certain temperature. While driving around, the cooling fan shouldn't turn on because the airflow over/through the radiator will keep the coolant at the normal operating temperature. However if you're like me and live in a hot as hell place, the fans will turn on while driving around.

When you turn on the A/C, the cooling fan (towards the battery) will turn on and stay on constantly. The other fan (by the passenger side wheel) will only turn on when the compressor cycles on. Again this may stay on constantly if it's really hot out, but for the most part that's how the fans work.

Easy way to test functionality of your fans. Start the car. Don't turn on the A/C. Unplug the coolant sensor from the water neck (between the valve cover and air filter box). Both fans should turn on. If they don't, you have a problem.

Your problem can be one of the following (troubleshooting steps are follow each situation).

1. Your fan motor(s) are toast. To test this, unplug the connection to the fans. Take jumper wires (a 30a fused wire and a non-fused wire) and connect the fused wire from the B+ terminal to the +12v terminal of the fan. The other wire goes to the B- terminal and ground terminal of the fan (again, I don't have the schematic in front of me so I can't say which is which, if you can wait 12 hours I can get it when I get home). The fan should turn on. If the fan does not turn on, the motor is dead.

If both fans turn on, the problem is either damaged wiring, a bad CTS or blown fuses/bad relay. To rule out the wiring from the relay box to the fans, reconnect the fans to the wiring harness. Remove the relay for the corresponding fan. Visually look at hte relay to check for burn/scorch/other damage. There are 4 terminals (85, 86, 87 and 30). Take note where the 30 terminal is and where the related connection is on the relay socket. Take the 30a fused wire and touch it to the B+ terminal and then to the corresponding terminal you found above. The fan should start spinning. Repeat this with both relay units to test the wiring from the relay box to the fan. If they both spin, you problem is either the relay you removed, the fuse or the coolant temp sensor. If the fans do NOT spin, disconnect the fans from the wiring harness. Take a test light and connect it to the chassis and the +12v terminal. Repeat the test. If the light comes on, your problem is in the physical connection. Repair the connection. If the light does not come on, there is a short or break in the wiring from the relay to the fan. Repair the wiring.

Check the two 30a fuses in the box inside the engine bay. Make sure they're not blown and test within specs. If these fuses are OK, check in the kick-panel in the drivers foot-well. Ensure there are now blown fuses and they're all seated properly.

If you've done all the above and the fans are STILL not turning on when you unplug the CTS, you can either test the CTS to see if it's within spec or just replace it. It's a $15 part.


If after all is said and done, you fans still do not turn on when the motor is running and you unplug the CTS, the testing needs to be repeated or take the car to a competent mechanic.
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#9
Tiberianx

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Good detailed write up 4thgenceli. The final last problem, if all else fails could lead to the PCM

#10
blondgirl921

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I'll have to work on it on the weekend. Thanks for the input. I'll let you know what I (hopefully) find out.





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