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Cooling fans

Tiny
HOJCAT
  • MEMBER
  • 2005 SATURN VUE
  • 3.5L
  • V6
  • FWD
  • AUTOMATIC
  • 129,000 MILES
I usually do in town and freeway driving in my car (Redline). Three years in a row, while driving mountainous roads heading from Phoenix AZ to CA and NV in July, the car overheated and it would not shift into overdrive. Twice it  blew out transmission fluid under the hood. The first time it happened in 2015 and the ODB codes were P0741 and P0742. I let it cool off and it drove fine as long as I did not exceed fifty to fifty five mph.
In 2016 I realized what was happening and so I lowered my speed and continued my journey.
July 2017, the same scenario occurred as in 2015. This time I let it cool off, returned home and rented a car. I did not get the ODB code as it reset itself before I reached home.
Sorry about the long background story.
My mechanic drove the heck out of it and could not get it to throw the P0751 or P0752 codes.
I took it to an auto electric shop and was told they could not diagnose the problem unless it threw the code in the repair bay.
As a last resort, I went to the GM dealer. They started telling me that it is most likely my transmission. So I left! It never, ever slips, has any shifting problems or other transmission issues. Only the three aforementioned times on the road trips in July.
I was driving in town this week and now the car overheated, throwing a P2555 code. It was then that I discovered that only one of the two cooling fans is functioning (the main fan on the left side). The fan on the right side does not kick at all, even when the air conditioner is running.
Maybe this has been the problem all along, I do not know.
Finally my question: Are there any tests I can do to determine if the fan motor is burned out before tearing the front of my car apart to replace it? I checked the fuses and they look good.
Thanks in advance!
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Sunday, August 13th, 2017 AT 5:36 PM

9 Replies

Tiny
STEVE W.
  • MECHANIC
  • 13,018 POSTS
Yes they can be tested on the vehicle with a simple test light and jumper wires.
https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

You just need to start at the beginning. First check that both cooling fan fuses are good. For that you connect the test light to ground/battery negative. Then turn the key on and probe the fuses on both sides. If you get a light on one side of a fuse but not the other the fuse is bad.
Next you will need to check the fan relays, The easy way is to start the engine and turn on the AC, one fan should come on. If you look at the fan relays there will be 3, relay 1 and 2 should be the same. Simply swap them and see if the fan stays on with both. If not then the relay that stops the fan is bad.

If both relays work then the next test involves disconnecting the fan that isn't working. Shut off the engine, reach in and remove the connector lock and disconnect the fan connector.
The right side fan (passenger side) has a Gray wire and a Black wire. If you connect a jumper wire from the battery negative terminal to the Black wires terminal on the fan and a wire to the positive side of the battery and touch the other end to the terminal for the Gray wire the fan should come on.
If it doesn't the fan is bad.
If it does then you have a wiring issue or control issue to that fan. Those would require using a scan tool to turn on the fan and using other testing.

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Tuesday, August 15th, 2017 AT 1:09 PM
Tiny
HOJCAT
  • MEMBER
  • 5 POSTS
I checked the fuses and swapped relay #1 and #2. The fuses and the two relays are good.
Then I tried (unsuccessfully) to remove relay #3. I couldn't figure out how to unplug it and gave up. I only had it pulled out about 1/16 inch; just a crack. I pushed it snugly back together. When I started the car and turned the air on, both fans are now working! I've been driving it all week and it hasn't overheated at all. The needle on the gauge stays at the normal temp.
I still think I have an electrical problem because when I start the car it is sluggish turning over. It was doing this before as well.
Thanks for your help! I'll post any further issues related to this.
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Saturday, August 19th, 2017 AT 8:50 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,018 POSTS
Sounds like it has a hot terminal and melted some plastic which is why it won't pull free. Pulling it up and down probably moved it enough that it's making a connection because it cleaned off a contact.
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Saturday, August 19th, 2017 AT 5:16 PM
Tiny
HOJCAT
  • MEMBER
  • 5 POSTS
So by a hot terminal, you mean that there is a short causing the plastic to melt?
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Saturday, August 19th, 2017 AT 9:43 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,018 POSTS
Not a short, those fans draw a lot of current. What happens is that the current flow generates heat. The heat causes the terminal to weaken which makes a loose connection. That in turn causes more heat because of the higher resistance. The terminal socket gets melted by the heat and some of the plastic gets into the terminal and you park the car. The plastic solidifies and suddenly the fan doesn't work.

My normal process is to replace the carrier for the relay, either the fuse box, relay center or whatever. OR it is also possible to go into the box, find the correct wires and wire in a relay outside the box, in many cases you can use a better relay and not have the problem again. It's not as hard as it sounds, BUT it's not something I recommend everyone try. Some shops will do it some won't.
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Saturday, August 19th, 2017 AT 10:41 PM
Tiny
HOJCAT
  • MEMBER
  • 5 POSTS
Thanks Steve,
I haven't had a chance to work on the car yet. However, since getting the fan to work, whenever I turn the steering wheel with the air cond blower on high, the blower cuts out and blows like it is on a lower speed. It has never done this before. Would that hot terminal cause the sluggish starting and blower issue too?
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Friday, August 25th, 2017 AT 3:51 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,018 POSTS
Turning the wheel should not make anything change. The description makes it sound like either a bad ground or power feed rubbing on the steering equipment. Look around the moving parts of the steering for a wire or harness rubbing, both under the hood and under the dash. Check and clean both ends of the battery cables as well, especially the engine ends. These type of issues can be hard to track but if the short is enough it can melt the wiring and cause a fire.
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Friday, August 25th, 2017 AT 8:54 PM
Tiny
HOJCAT
  • MEMBER
  • 5 POSTS
Okay, checked all wiring, installed a new fan relay, coolant sensor and battery.
No issues with battery drain now but it's overheating all the time now. Is the thermostat easy to get to? I'm going to replace it next.
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Monday, September 11th, 2017 AT 11:17 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,018 POSTS
Pull the battery, drain the coolant below the thermostat, remove the two bolts and the thermostat. Reverse to replace it.

BUT before you do that. Get a cooling system pressure test kit and see if the cooling system will hold pressure.
https://www.2carpros.com/articles/radiator-pressure-test
Just in case it's something like a bad head gasket that failed from the stress of the past.
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Monday, September 11th, 2017 AT 6:28 PM

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