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Radiator fan wont turn on without ac + ac problem

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Old 3/15/17, 09:35 PM   #1
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Radiator fan wont turn on without ac + ac problem

Hey guys, most of my threads don't get a lot of replies so hopefully this one will.

My radiator fan won't turn on unless I turn the ac on. Once I turn the ac on, the fan will turn on and stay on even if I turn the ac off. That seems to be my work around for now. I haven't done this when the car is cold, only when it's hot. I'll do any other tests you guys suggest as long as I have the tools/ability to do it.

My second "problem" is with the ac itself. I use my ac literally 3 times a year at the most so it may be completely normal, I don't know. When I turn the ac on, theres like a grinding noise behind the dash or in the engine bay. I THINK it eventually goes away. I don't know why but for some reason it's hard for me to tell. My exhaust is pretty loud so that doesn't help. When I pop the hood I don't hear the grinding noise, but I hear a low pitch whine. When you look at the bottom left of the engine block, I think whats called the tensioner will move back and fourth every few seconds. It isnt wobbling like it's loose, it's like it engages and disengages. When it moves one way, or "engages", it makes the whine. When it "disengages", it goes away and sounds normal. It's not a squeal at all. The belt looks good.

Thanks for reading my wall of text. I looked up the grinding problem and there was only one thread I saw and it didnt get resolved. There were a good amount of fan threads but not specifically like my problem.
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Old 3/16/17, 07:03 AM   #2
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First does the car over heat if you don't turn on the AC?

The grinding noise is it there when you just turn the fan on? if it is, Then it is the blower motor giving out. Easy fix.
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Old 3/16/17, 07:58 AM   #3
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If the temp is below what the fans are set to come on at and you turn the A/C on high the computer will turn the fan on regardless of the temp. I believe the stock settings are around 206 degrees, so if you're below that it maybe why.
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Old 3/16/17, 11:25 AM   #4
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Hey guys, the car hasn't overheated, but I think it's only because I don't let it get past 220. It should definitely kick on by itself.

They grinding noise IS there when I turn the fan on, but it's only when the a/c is on. After I turn the ac off, the fan will stay on and the grinding noise is gone.

I drove home today averaging between 50 and 70 mph and the temp got up to 215 in that time period and went to 220 by the time I got home. It was 45 degrees at the time so I really want to get this fixed before summer. When I put the key in the on position where the electrical stuff is powered, but the engine is not running, there is no grinding noise when I turn the ac on.

Last edited by Left Lane Muscle; 3/16/17 at 11:28 AM.
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Old 3/16/17, 12:06 PM   #5
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You're right at those temps the fan should come on, and since it does come on with the A/C on, then the fan and it's relay aren't bad. So for some reason the computer thinks the temps are to low to turn the fans on, unless the A/C is on and then it doesn't care what the temp is. How are you monitoring these temps, are you using a scan gauge and those are the temps the computer sees? If not and you're using a stand alone gauge, then maybe a bad sensor and the computer isn't seeing the real temp.
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Old 3/16/17, 12:40 PM   #6
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It's a JEGS water temperature gauge. I bought my car used and it came installed. I believe the sensor is located between the top of the radiator and the thermostat. This sounds weird, but I don't really know where my tstat is. Everywhere I've looked on the internet shows it towards the middle right of the front of the engine but mine isn't there. The top radiator hose goes to a upper left part of the front of the engine. It looks like the top of a thermostat housing but I don't know for sure without taking it apart.
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Old 3/16/17, 01:27 PM   #7
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This is what I'm talking about. The red is what I think is the thermostat, and the blue is what I think is the sensor to the Jeggs gauge. When I look down and to the right, there is no thermostat like there seems to usually be. My car has the roush supercharger kit so maybe it was relocated?
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Old 3/16/17, 01:50 PM   #8
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Quote:
Originally Posted by Left Lane Muscle View Post
This is what I'm talking about. The red is what I think is the thermostat, and the blue is what I think is the sensor to the Jeggs gauge. When I look down and to the right, there is no thermostat like there seems to usually be. My car has the roush supercharger kit so maybe it was relocated?
I believe you are correct on both.
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Old 3/16/17, 01:52 PM   #9
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What year is your car? Oh, I see a TVS on top of your motor. It may have moved the thermostat but the thermostat won't have anything to do with your fan turning on and off.

Check all of your wiring. The fan and relay seem like they work properly so the relay is not getting a signal from the computer for some reason.


With the AC not working and the tensioner jumping when it is engaged leads me to believe that there is something wrong with the compressor. A grinding noise may be indicative of a bearing failure.
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Old 3/17/17, 09:39 PM   #10
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Today I was doing a lot of running around and had the chance to do some testing. I'd start the car, it was of course up to temp because it was only off for a few minutes, turn the a/c on and check to see if the fan was running. It was. One test I turned the ac off and checked the fan before turning off the car once I got to my next stop and the fan was no longer on. The next time I did the same but left the ac on. It also was not running. I really don't want to take it somewhere but I know nothing about how the a/c works. I don't know if the problems I'm having are related or they just compliment eachother.
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Old 3/17/17, 09:49 PM   #11
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Wiring problems can be hard to diagnose. The A/C shouldn't have anything to do with the engine fan I don't think. You have access to a wiring diagram? At this point I would start chasing wires and looking for something out of place, shorted, or crossed.
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Old 3/17/17, 10:57 PM   #12
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I don't but I'd assume a simple google search would find it for me? I'll try it out
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Old 3/18/17, 09:49 AM   #13
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You can get one from the factory service manual or a Haynes/Chilton book from you local auto parts store. Your car is an 06, right? I have copies of some of the sections of the FSM, including wiring diagrams. Try this out (attachment)
Attached Files
File Type: pdf WIRING.pdf (1.78 MB, 17 views)
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Old 3/18/17, 10:28 AM   #14
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Wiring problems can be hard to diagnose. The A/C shouldn't have anything to do with the engine fan I don't think. You have access to a wiring diagram? At this point I would start chasing wires and looking for something out of place, shorted, or crossed.
When you turn on the AC the fan is supposed to come on.
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Old 3/18/17, 01:42 PM   #15
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When you turn on the AC the fan is supposed to come on.
It does that on your car? I've never seen it behave like that on my '06, fan only comes on/off with temperature. Just double checked by warming the car up to operating temp to give it a test run. My A/C has no change on the cooling fan. Engine running/not, warm/cold
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Old 3/18/17, 09:22 PM   #16
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I'm going to keep trying to figure it out. I'm on spring break right now and will be back home Monday so. Everything I could come up with now is just theory anyway. I just looked at the pdf you put up and wow. I don't have the first clue how to read that. I'll look at it a bit tonight. Thank you for the post

Last edited by Left Lane Muscle; 3/18/17 at 09:27 PM.
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Old 3/19/17, 02:31 PM   #17
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It does that on your car? I've never seen it behave like that on my '06, fan only comes on/off with temperature. Just double checked by warming the car up to operating temp to give it a test run. My A/C has no change on the cooling fan. Engine running/not, warm/cold
You have something wrong then. The high speed fan should always come on with the A/C unless you have a separate fan for the condenser. The fan needs to come on to draw air over the condenser or the freon boils and you get a high pressure situation and the AC will cut out, or should at least. And yes my fan turns on with the AC even when the motor is cold.
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Old 3/19/17, 02:41 PM   #18
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I'm going to keep trying to figure it out. I'm on spring break right now and will be back home Monday so. Everything I could come up with now is just theory anyway. I just looked at the pdf you put up and wow. I don't have the first clue how to read that. I'll look at it a bit tonight. Thank you for the post
I had an epiphany last night when I was thinking about your situation. The fan coming on with the AC is the high speed fan. Normally as your motor gets warmer the low speed fan is supposed to kick on at a certain temp and then if the temp continues to rise the high speed mode kicks in. What may be happening is the fan is coming on with the AC as it is supposed to and maybe keeps running because you are in that zone where the high speed fan kicks in and not down to the temp where it kicks off. which is at a lower point than when it turns on. If the resistor for the low speed fan is out it may explain why it seems like the fan is not kicking on when it is supposed to.

The low speed resistor may explain why you start the car and wait and the fan doesn't kick on until you run the AC. Then when you turn the AC off the fan should continue to run for a while or maybe the car got up to temp while the AC was on and the high speed fan stays on. Either way it may explain why it seems like the fan works sometimes and not other times.
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Old 3/19/17, 04:51 PM   #19
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You have something wrong then. The high speed fan should always come on with the A/C unless you have a separate fan for the condenser. The fan needs to come on to draw air over the condenser or the freon boils and you get a high pressure situation and the AC will cut out, or should at least. And yes my fan turns on with the AC even when the motor is cold.
That makes a lot of sense.

Cold but running, right? I did a datalog and when I hit the A/C button and the compressor's clutch is commanded, the fan is commanded on. What I'm seeing though is for me its the low speed fan being commanded on. Maybe hit had to deal with it only being 45 deg out? The high speed did come on at one point because the car got up to temperature and was idling for a while. The other thing I saw was the A/C clutch won't command on unless the engine's running.

Either case, I definitely have something wrong with the low speed fan because even when its commanded it isn't spinning. I can hear the relay clicking away, but its not actually coming on.

Going to have to look into this more, may be the same reason why Left Lane's low speed fan isn't coming on.

Last edited by Cavero; 3/19/17 at 04:57 PM. Reason: added temperature outside
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Old 3/19/17, 04:55 PM   #20
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I had an epiphany last night when I was thinking about your situation. The fan coming on with the AC is the high speed fan. Normally as your motor gets warmer the low speed fan is supposed to kick on at a certain temp and then if the temp continues to rise the high speed mode kicks in. What may be happening is the fan is coming on with the AC as it is supposed to and maybe keeps running because you are in that zone where the high speed fan kicks in and not down to the temp where it kicks off. which is at a lower point than when it turns on. If the resistor for the low speed fan is out it may explain why it seems like the fan is not kicking on when it is supposed to.

The low speed resistor may explain why you start the car and wait and the fan doesn't kick on until you run the AC. Then when you turn the AC off the fan should continue to run for a while or maybe the car got up to temp while the AC was on and the high speed fan stays on. Either way it may explain why it seems like the fan works sometimes and not other times.

I definitely noticed during my datalog that the fan (low speed in my case) is still commanded on for a while after turning the A/C off.
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