Radiator cooling fan still running at high speed

[Ringmaster]

I've been dealing with some other car issues so now I'm back to this. My 03 V8 Sport's radiator fan is still going into high speed mode approx. 10 minutes after hitting the road. Cooling system has been flushed, new thermostat has been installed. Yesterday while at the dealer buying a new battery I asked the guy at the parts counter where the cooling fan's temp. sensor was located. He came up with no less than 4 temp sensors on the engine and he didn't know which one controled the fan. Does anyone know where the sensor is located that turns the fan on and off is located? Others have also mentioned a fan relay. Where is that located? Thanks.

 

[1LoudLS]

i would think if the problem was the fan relay then the fan would either never work or never stop, since it runs for 10 mins before it go into high gear, i would lean against it being the relay. have you checked to make sure the radiator is not clogged with debris and leaves?

 

[Ringmaster]

so if we assume it's not a relay what about a temp sensor that is reading wrong? I did find a small amount of leaf crap in the small space between the condenser and the radiator and I cleaned that ou

 

[joegr]

In theory, the PCM uses all of the engine temperature sensors plus the AC high side pressure sensor to determine the required fan speed. The fan is not just an on/off or even a high/low fan. The PCM can set the fan to any of multiple different speed settings, from off to maximum.

How do you figure out what is going on to solve this? It actually pretty easy, but you need the right equipment. With a Ford specific scan tool, you can read out the values of all of the temperature sensors and the AC pressure sensor and from that determine which one(s) are causing the PCM to call for max fan. Once you locate the sensor, you will have to actually measure temperature or pressure to determine if the sensor is at fault, or if it is just reacting to an engine cooling problem.

My bet, just from your description that it happens after ten minutes of driving is that it is not a sensor problem, but is instead an engine cooling problem.

 

[Ringmaster]

Thanks for the replies. As I stated I did find a small pile of crud between the oil cooler (I guess that's what the thing is between the condenser and the radiator) and the radiator. I can't figure out how leaves etc. get in there with a top and bottom cover. I brushed the stuff to the sides using a radio antenna. Nothing else fits in there. Anyway there is no room in this space to do anything so how do the people who suggest checking/cleaning the radiator fins pull this job off themselves? Pulling the radiator out doesn't look easy.

 

[joegr]

Compressed air or high pressure water hose?

 

[Ringmaster]

I'm not sure compressed air or a water hose would hit the radiator since they would first have to travel thru the condenser and then the oil cooler.

 

[Ringmaster]

I was able to borrow one of those infrared temp readers today. Upper radiator hose gave a reading of 180f. I'm thinking I'm not overheating unless the full tilt fan is holding it that temp.

 

[rt2barbers]

Damn, old age and beer are stealing my short-term memory. Replaced the radiator on my '02 in September because of a leak and, isn't there a support panel under the condenser-oil cooler-radiator that can be dropped after the air deflector is removed that may enable cleaning the leaves and stuff out from the bottom? Joe, a little help.

 

[Ringmaster]

I pulled the plastic pannel off at the bottom and there was another panel behind it blocking me from getting at anything from the bottom. I couldn't see how to get it off.