2003 LS V6 radiator fan doesn't work

[LeedsAL]

My car is a 2003 Lincoln LS with 3.0L V6 engine and automatic transmission, manufactured January 2003, 150K miles. This is the 2nd-generation car. Can any forum member tell me how to test the radiator fan and sensor system?

I bought the car a few months ago and I love it. It’s been running great until recently when it began to overheat. I had to replace the top radiator hose so I drained and refilled the cooling system, bleeding it carefully according to the instructions in the sticky post in this forum. I re-bled it to be certain. The last time I noticed hearing the electric cooling fan running was before the overheating problem started. It doesn’t come on anymore and I suspect that’s the problem. I drive this car daily and the weather has been cool lately, which means the temp needle doesn’t budge off half-dial level unless idling for extended periods, but I have to add small amounts of coolant frequently. I haven’t allowed it to hit max temp on the gauge and there’s no steam in the exhaust, so I don’t suspect blown head gasket or other engine damage. I’m aware of the degas bottle problem these cars have but, because the fan doesn’t come on, I suspect the fan is the problem rather than the bottle.

 

[joegr]

Test 1: Turn the AC on. The fan should come on. If not, you have a problem.

Locate the cooling fan connector(s). If you are lucky, you will have the setup with two, two wire connectors. If not, you have the single four wire connector (harder to troubleshoot).

Test 2: Check for battery power on the large red/yellow wire. If no power, then suspect the 60A in-line fuse. If the fuse is blown, your fan is probably bad too.

Test 3: With the key turned to run, check for 12V power on the small green/yellow wire. If no power, then check fuse F1.05 in the box under the hood.

Test 4: If you have the two, two pin connectors, unplug the one with the two small wires. Jumper +12V to the green/yellow wire (on the fan side, not the car side). Do not connect anything to the white/black wire. The fan should start and run at full speed. If it doesn't, then the fan is bad. If the fan does run, then your PCM is bad.

 

[LeedsAL]

Thanks, joegr, for the test proceedure. Your posts always seem to be concise and informative, this one no different. My car has the two-connector system for the fan but I haven't been able to work on it until today. Here's what I discovered.

1. The fan runs but not at full speed. The last time I noticed it running at noise level loud enough to indicate full speed was a few weeks ago. At that time, I could hear it easily over the idling engine. Today I couldn't hear it at all. With ambient temp outside apprx 78 degrees, I turned the a/c on max and used a flashlight to look at the fan. Although it wasn't running fast enough to hear it, I could see that it was running and cycling on and off.

2. I intentionally tried to make the car overheat and succeeded by running it sitting still at 2500 RPM with a/c on max for 10 min. The fan was running but not fast enough to maintain normal temp.

3. I found the voltage you indicated in tests 2 and 3.

4. Test 4 indicates possible problem. When I attach +12V jumper wire as you indicated, the fan doesn't run at all ... full speed or otherwise. I ran the test with ignition switched to run but car not cranked; I also ran it with ignition off; same result in both cases. Does that mean the fan is faulty despite the fact that I observed it running (see note 1 above)?

Thanks for your help.

 

[joegr]

Yes, that means the fan is bad.

 

[LeedsAL]

Joegr … as always, thanks for your help! I bought a used fan on ebay and installed it. It seems to have fixed the problem.