cooling fans - Toyota Nation Forum : Toyota Car and Truck Forums

spaceman · 09-16-2009, 11:44 PM

I have a camry 2.0 liter 3sfe engine. Cooling fans sometimes run the way they are meant to when the ac is on. Sometimes they both shut off. I noticed as soon as I increase engine rpm they start spinning into action. I don't know if it could be the relay. coolant temperature sensor, or something else in the circuit. anyone have this problem?

DM89 · 09-19-2009, 10:09 AM

Is your car overheating? Does the ac work? There is a high pressure ac switch that controls cooling fan operation as well as the coolant temp sensor. It is located under the battery. Check the connector for corrosion. it might be giving a bad reading.

ford_jj · 09-19-2009, 10:58 AM

Quote:

Originally Posted by DM89

Is your car overheating? Does the ac work? There is a high pressure ac switch that controls cooling fan operation as well as the coolant temp sensor. It is located under the battery. Check the connector for corrosion. it might be giving a bad reading.

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white90dx · 09-21-2009, 02:02 PM

The cooling fans should only run while the AC compressor is on (low speed, series operation). The AC compressor does not run constantly while the AC is on. From your description, they seem to be acting exactly as designed.

Are there any other problems with the car that led you down the path to notice the fan operation?

-Charlie

nuron · 09-21-2009, 04:10 PM

Charlie do you know what the readings should be for the fan temp switch thing on top of the thermostat? I'm trying to narrow down why I have a fan running when I first start it in the morning. Shouldn't they stay off to let the engine to to optimal temps first?

spaceman · 09-21-2009, 11:03 PM

Quote:

Originally Posted by white90dx

The cooling fans should only run while the AC compressor is on (low speed, series operation). The AC compressor does not run constantly while the AC is on. From your description, they seem to be acting exactly as designed.

Are there any other problems with the car that led you down the path to notice the fan operation?

-Charlie

yes, there is a problem with the ac. When those fans kick on when I am at idle ie: at a stoplight the ac blows nice cold air! When I drive down the road the fans seem to come on and I get nice cold air. Sometimes when I am at idle those fans come on but when they decide not to spin then is when I get the warmer air.

white90dx · 09-22-2009, 02:47 PM

Quote:

Originally Posted by spaceman

yes, there is a problem with the ac. When those fans kick on when I am at idle ie: at a stoplight the ac blows nice cold air! When I drive down the road the fans seem to come on and I get nice cold air. Sometimes when I am at idle those fans come on but when they decide not to spin then is when I get the warmer air.

Do the fans ever run on the 'slow' speed?

Generally, if the AC compressor clutch is active the fans should be running in series at a low speed. If the coolant temp is high coming out of the radiator or the AC line pressure is too high, the fans run in parallel at a high speed.

If something is wrong, often the fans won't run at the low speed when the AC is on. Check for sticky relays in the engine bay fuse box... There might also be a wiring problem, but its unlikely.

-Charlie

white90dx · 09-22-2009, 02:49 PM

Quote:

Originally Posted by nuron

Charlie do you know what the readings should be for the fan temp switch thing on top of the thermostat? I'm trying to narrow down why I have a fan running when I first start it in the morning. Shouldn't they stay off to let the engine to to optimal temps first?

It should be open to ground unless the coolant coming out of the radiator is over 190*F (or something like that). If the water is hot, it shorts to ground.

Check your relays in the fuse box - one of them might be stuck on. Is it only one fan that's on?

-Charlie

spaceman · 09-24-2009, 07:50 PM

When you say it could be a sticky relay, do you know how to test a five pin relay? I don't subscribe to any software programs to guide me through. I can't figure out how to test this little bugger. I hate to swap parts out even though the relay is not that expensive, about $20.00. Let me know if you have any ideas on this.

white90dx · 09-24-2009, 08:05 PM

Often the relay will have a diagram shown directly on it. I can't remember if the stock relays do though...

You can try tapping on the various relays while things aren't acting as you expect to see if the behavior changes...

Also, you can probably pick up a whole set at a junkyard for cheap/free.

-Charlie

spaceman · 09-24-2009, 11:01 PM

the five pin relay has three pins on the top, with two pins under the first pins on the left . the two pins on the left seem to be the energizer pins with the pins to the right (top and bottom) seem to be the switch pins. With the ground pin being the third pin on top to the right. If i energize these two pins on the left (top and bottom) with a energy source what should the reading be on the switch side?

white90dx · 09-25-2009, 12:18 PM

If you can energize the relay coil, you should hear a click.

In a 5-pin relay, there will be a common connection, a normally open connection (closed when energized) and normally closed connection (open when energized) along with the two coil connections.

It should be easy to test if you have two pieces of wire, some spade connectors and a multimeter.

Find the two pins with resistance between them (but not a short) and apply power across them. If you hear a click, its working. You can verify the other connections are working with the multimeter if you like.

-Charlie

white90dx · 09-25-2009, 12:20 PM

Quote:

Originally Posted by white90dx

It should be open to ground unless the coolant coming out of the radiator is over 190*F (or something like that). If the water is hot, it shorts to ground.

Check your relays in the fuse box - one of them might be stuck on. Is it only one fan that's on?

-Charlie

I just noticed I was backwards here... the coolant temp switch for the fans is shorted to ground unless it is hot. That way, if you unplug the connector, the fans should turn on high.

-Charlie

***88' camry v6 LE*** · 09-26-2009, 12:43 AM

Does anyone have any idea why my fans would be stuck on the whole time? I'm guessing I have a similar problem like Spaceman. My vehicle is the v6 and as soon as I turn my key to the on position the fans turn on and stay on. The only time they shut off is when the car is turned off. I have pulled a fan relay switch under the hood... and of course the fan stayed off. However, I need the fan to kick on so I don't overheat. Should I first start with replacing the relay switch and going from there?

Ok, looks like I was wrong when I said I pulled the relay switch. It's the #1 relay switch under the hood of the car. I'm guessing it's the high speed relay switch. When this switch is pulled the high speed does not kick on or even stay on like it has been. I did notice last night with this relay pulled that the fans still kicked on, but only at a low speed. I check out my local Autozone for a new relay, and found out they are about $50.00 with tax. I think I'll try the junk yard today to try my luck there first on a relay.

Does anyone else have any other ideas on what I should maybe look at?

Thanks, Jon

Mike Gerber · 09-26-2009, 03:57 AM

"Should I first start with replacing the relay switch and going from there?"

See if any of the other relays in the relay box are identical to the one you pulled. If they are, swap it with this one for a test.

Mike