Need cooling system help!

Ryanls

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Ok, so I am a new site member, and I have looked at this site for LS advice for a long time.
I have a 2003 LS, V8.
My cooling fan comes on but it is very slow. I have taken it to the Dealer to be looked at, and I was told that it needs a cooling fan, the cooling fan relay and a temp sensor. The gauge on the dash reads thet it is normal, but when I turn on the A/C, the fan does not speed up and I can tell it is running hot!


Please help!
 
How can you tell?!?!?! whats the temp gauge say?????

+1

I guess its possible for the temp sensor to fail (though if it displays normal and not Cold, I'd be surprised). Are you doing these tests with it idling in park? If you really ran hot for any length of time, the cooling system would boil and dump its contents all over the ground.
 
Ok, so I am a new site member, and I have looked at this site for LS advice for a long time.
I have a 2003 LS, V8.
My cooling fan comes on but it is very slow. I have taken it to the Dealer to be looked at, and I was told that it needs a cooling fan, the cooling fan relay and a temp sensor. The gauge on the dash reads thet it is normal, but when I turn on the A/C, the fan does not speed up and I can tell it is running hot!


Please help!

Okay, either you misunderstood something, the dealer is incompetent, or the dealer is crooked.
There is no fan relay on the LS. The fan power connects straight to the 12V battery bus, with no switches or relays between. (It does have a fuse.) A switched control signal goes to the processor in the fan, as does a PWM speed control signal from the PCM. If the PWM signal fails or is disconnected, the fan goes to maximum speed and stays there as long as the key is on. It is possible that some fault on the fan motor prevents it from turning fast enough, but it is rare. In any event, there is no relay to replace.
 
...
Is there a way to trip out the relay so it runs the fan full speed? This may show that the fan is fine (or confirm its broken), but the relay is toast. Surprised they didn't mention the pump that powers the fan.

There is no relay.
 
Why does it not suprise me that they tried to rip me off?

The gauge reads cold when started in the morning, then rises like it always has.

I bought the car from Carmax and it had 45K on it then, Now it has 110K. I really like the car but it is starting to develop some problems. But what can I expect since I have only had to do regular maint. I guess they just dont make them like they used to.

Is there anyway to test the fan? Is it a simple matter of disconnecting the plugs in the fan and connecting 12v to the large wires (pos and neg)??

Thank you guys so much!!!!
 
Why does it not suprise me that they tried to rip me off?

The gauge reads cold when started in the morning, then rises like it always has.

I bought the car from Carmax and it had 45K on it then, Now it has 110K. I really like the car but it is starting to develop some problems. But what can I expect since I have only had to do regular maint. I guess they just dont make them like they used to.

Is there anyway to test the fan? Is it a simple matter of disconnecting the plugs in the fan and connecting 12v to the large wires (pos and neg)??

Thank you guys so much!!!!

You have an 03, so you should have two two-pin connectors from the cooling fan. One of these has large wires, and the other one has small ones. Leave the large ones connected, that's the 12V power feed and is always hot. Disconnect that one with the small wires. One of the two wires is the switched ignition feed. If you connect it to +12V without the other wire (PWM signal) connected, the fan will go into failsafe high speed mode. I can look up the correct wire color tonight for you.

Edit: It's the green wire that you want to connect to +12V to test high speed operation. Make sure that the small two-pin connector (with the green wire and the white-black wire) is disconnected first.
 
Last edited:
If it is in fact the fan, you can supposedly buy just the motor per this post but I can't tell if he is referencing aftermarket or OE

That's aftermarket.

The OEM fan has the speed controller built-in. You have to buy the whole assembly, AFAIK.
 
haha I just confirmed that and tried to delete my post but you were too damn quick again! My logon gets messed up on my work computer when I use the back button so I had to log on again. Edit option wasn't there when I went back to the thread, and then it was and you quoted in the meantime.
 
G-rell,
Yes I am assuming that it should kick up to a higher speed. At what temp does it go from low-medium to high? I can check it with a laser thermometer on Tuesday. I am just afraid it will cook and pop a head gasket.

Joegr,
So if I connect 12v to the small green wire and it speeds up it means everything is ok? (with the fan)?
 
G-rell,
Yes I am assuming that it should kick up to a higher speed. At what temp does it go from low-medium to high? I can check it with a laser thermometer on Tuesday. I am just afraid it will cook and pop a head gasket.

Joegr,
So if I connect 12v to the small green wire and it speeds up it means everything is ok? (with the fan)?

Yes.

Turn the AC off when you park the car the next time. The next day when you start the car, the fan should stay off for the first little bit. Now turn the AC on, and the fan should come on a medium to medium high speed. (The fan is not a two or three speed fan, it is more like a ten speed fan.) It will not go to maximum (even with the air on) until the engine is hotter than it would like.

You don't have to worry too much about the head-gaskets. The LS has failsafe cooling and will switch to low power mode before it is way too hot. If that still doesn't do it, it will actually shut the engine down.

I am still curious as to what indication you have that it is running too hot? It is normal for the engine and underhood area to be very hot. If you smell anything burning, it is more likely to be because of an oil or coolant leak than due to actual overheating.
 
Does smell a little like burnt plastic when sitting in traffic........ Hmmmmmm..
 
Mine just started overheating yesterday! I changed the thermostat last night. And today it still overheated, something I did notice was that the fan was not kicking in any faster as it got hotter. I searched on here and saw that some people that had the same symptoms changed their cooling fan pump actuator and that did the trick. Only problem I'm having is finding where the hell it is.
 
Mine just started overheating yesterday! I changed the thermostat last night. And today it still overheated, something I did notice was that the fan was not kicking in any faster as it got hotter. I searched on here and saw that some people that had the same symptoms changed their cooling fan pump actuator and that did the trick. Only problem I'm having is finding where the hell it is.
He has a gen 2 with electric. I overlooked that at first as well. It sounds like you have an '00-'02. Follow the fan fluid (that always sounds funny) line from the reservoir up top down to the pump. A quick search yielded this thread that describes where it is and how to replace it
 
I changed the fan on my '03 LS8 a couple of years ago. It was a PITA. I've changed a few fans in my life and this one was the worst. It probably took me about 1.5 hours. I believe the fan cost me about $300 wholesale.
 
i still don't see the problem, do you just want to test the fan to make it go to high, how and why do you think the car is over heating. I have a 04 v8 with 140k now and a 01 v8 with 230k now and the gen 2 fan is pretty good and it seems like the temp gauge is doing its job. a competent mechanic will have a scan tool to measure the temp in real time and it should be around 210 to 224 degrees. if so its the fan is fine. I think you are getting riled up for nothing. you also said that there other issues with the car so what are they so we can help
 
He has a gen 2 with electric. I overlooked that at first as well. It sounds like you have an '00-'02. Follow the fan fluid (that always sounds funny) line from the reservoir up top down to the pump. A quick search yielded this thread that describes where it is and how to replace it

Thank you very much for that. I know what I'll be doing this weekend!
 

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