I bought a 2002 mcs from a private seller in late August. I took a decent test drive and drove the car 2 1/2 hours home without incident. A few days later my wife and I took a road trip. Afterward, I sat in the car in the drive to program my stations in the radio. With the AC running, the car overheated after a few minutes. It was a warm day.
After finding this site (which is a great place) and reading the sticky about the low-speed fan resistor, I assumed I found my issue. No big deal. Since the car was new to me, I elected to replace the cooling fan rather than splice in a new resistor. This last weekend I installed an aftermarket RockAuto cooling fan. Despite being disappointed with the Bentley manual's instructions, and being thankful for YouTube and this site, the replacement went without issue.
Afterward, I allowed the car to idle in the drive to test the new fan. Since it was a cool day, the engine did not require the cooling fan. The temp gauge never exceeded the normal driving range. Engaging the AC made no difference.
I ordered a bluetooth OBD device to determine the actual temp of the coolant. I installed it today.
I allowed the engine to run as I monitored the temp. The temp never exceeded 150 at idle, so I revved the engine. After a few minutes the temp climbed to 200 or so. Soon afterward the temp exceeded the 221 mark...no low-speed fan. It passed 234...still no fan. I allowed it to reach 240 before shutting it down. Neither the low-speed or high-speed fan kicked-in.
I rechecked the connections and the fuses...

Since the OBD obtained the temp from the ecu, I think I can assume that the temp sensor is ok.

I would appreciate any ideas on what to do next.

btw, there were no fault codes generated or stored.

Thanks in advance.

 

Sounds like a sticking thermostat.

Sent from my Galaxy Nexus using NAMotoring

 

You need to find out if your fan does not work, or if your fan does not get power.

The plug for the fan is on the drivers side (edit: Druvers side of fan shroud, near where you open the hood) There are 3 wires. On the fan-side of the plug, there's a Red wire, a Black wire, and a Thin Red wire.

The red one goes straight to the fan, and this is the power for high speed fan.

The skinny red one goes to a resistor on the fan housing, and this is power for the low speed fan.

Black one is ground.

Jump the fan to 12v power and see if it works.

Another way to do the same thing is to use a test light or 12v meter to determine if power is coming out of the car-side of the plug when you start it and turn on the AC, or warm it up.

If the fan does work, but is not getting power, next I'd check the relay in the car.

BTW, this is worth mention, but I can't comment a lot about it, because I have a later model car,.. Don't know first hand. I read somewhere that in early years the Cooling Fan was dependent on the PowerSteering Fan somehow,.. You loose one, and they both don't work. Again I can't explain it well, but with a google search, I'm sure there's info -also some cars were corrected at dealership by a service bulletin or recall or something.

Also I think there's more than one fuse in the circuit.

Hope that helps

 

Thanks for the responses. I will check for power to the fan after work.

I forgot to mention in my initial post that my mcs was mfg'd in July 2002.

 

Alex is right...power steering fan & its fuse should be your primary suspect.

 

+1
The small PS fan on pre Jan 2005 production cars can get sticky (sand/water gets in the bearings)....results in a 5 amp (if I remember right) fuse blowing..basicly it removes the power to the relay, that provides power to the radiator cooling fan......all PS fans on gen1 cars have this issue... But the wiring was changed...some cars were rewired under a campaign/service bulletin to fix this problem starting in 2005.....odd note/fact...with the new wiring, the backup sensor (if installed) would now be the item that stops working, giving you a warning the fan was now stuck/fuse was blown...
So no low or hi speed fan...and no PS cooling fan (kind of a big thing..the electric pump is about $600)....
The PS pump fan is an easy swap...a couple screws and a plug...if you find the oil drain plug...then look back about a foot...that is the PS cooling pump fan...looks like a computer cooling fan....screwed to a bracket (early ones are rivited)...can be bought on the bracket or bare....
Fuse should be in the drivers side fuse box (I think, some early 2002 cars are not 100% matching even late 2002+ cars)...some were assembled with some preproduction parts...so just know the cars birth date/ production date...located on the drivers side door jamb...some parts you might need will be depandant upon this date....

 

After reading the above responses, I went out to the parking lot to recheck the fuses. To my delight (I hope), fuse F05 was blown. It is a 5 amp fuse that the fuse box lid simply indicates is for the engine. The Bentley manual, to its credit, indicates is for the cooling fan. I cannot specifically recall checking this fuse either before or after replacing the fan. So...hopefully all is good, although I think I will check the PS fan before it gets too cold out just to be safe.
I wonder what made the 5 amp fuse blow? I hope I won't lose too much sleep...

 

Likely that debris in the ps fan, preventing it from turning blew the fuse

 

Still, check the PS fan. Turn your A/C on to activate your high speed. It's supposed to work with it. Here's a primer of our cooling system:

Thermostat begins to open at 89-92° C (192° F - 198° F) and is fully open at 103° C (217° F).

Expansion Tank Cap Cap pressurizes the system to 1.1 bar (16 psi) at which point the cap valve will lift to relieve pressure.

Cooling Fan

Radiator Fan is a nine bladed fan measuring 400mm in diameter, driven by a 350 watt motor controlled by the EMS2000.

Low speed is switched on at 105°C (221° F) coolant temp and off when the temperature drops to 101°C (214° F).

High speed is switched on at 112° C (234° F) and remains on until the system coolant temperature drops by 4° C (7.2° F, so @ around 227F) at which point the system will revert to Low Speed.

The cooling fan will also operate on Low Speed when the Air Conditioning is switched on and system pressure reaches 8 bar (116 psi). Should the Air Conditioning system pressure rise to 18 bar (261 psi), the fan will automatically run on the High Speed.

 

Thanks for all the help guys.

I will check the power steering fan this weekend. I am trying to resolve any issues before the snow flies.

Thanks again.

Bob

 

+1 on whats was said above. They covered very well. If you look at the fan and it stuck very badly , we have the fan options below. Since you are a 2002 you might have the older P/S fan without the grille. If you have the new fan with the grille , we have the fan by itself. I have unbolted them in the past and tried to clean the sand / dirt between the fan blade cap and the housing base with some luck (spinning it then using compressed air in the small space between ). Give it a good try and see if you can get it to spin free again.

Here are the items and pics.

#1 Pump Part # 32416778425

http://www.ecstuning.com/Search/SiteSearch/32416778425/



&

#9 P/S Pump Cooling Fan W/ Grille Part # 32416857718


http://www.ecstuning.com/Search/SiteSearch/32416857718/




And

PS Fan only. Part # 32416781742


http://www.ecstuning.com/Search/SiteSearch/32416781742/ES2627297/



Thanks and hope that helps.