hey everyone

i am having a problem with my thermo fans, they don't seem to be going into high speed mode. i have tried the thermatic fans diagnostic and when i put it into gear, the fans both come on, but, at full speed, instead of low speed as the book says.

i have tried replacing relays, with no luck. i have also checked continuity from ecu module to relays, all is good. have tried bypassing the relays, as specified in the manual, and fans work as they should. have also tried another ecu, and it has the same problem.

Problem is if i put a newspaper infront of the radiator, and get temp to 3/4's, the fans still stay at low speed.

anyone have any ideas how to fix this, or what might be the problem with it not going into high speed.

Did you try new relays or were they from another car? You are correct in that the koeo diagnostic should run in slow speed mode. To check for medium speed operation, undo the screw on the relay block and rotate it 90 degrees so you can see the contacts underneath. Get 2 wires and connect them to the right hand contacts of relays 2 and 3 (see photo medium.jpg). Switch the ingnition on and the fans should run in medium speed mode (one fan high speed and the other half speed). Next get a third wire and ground out the right hand pin on relay 1. This will simulate high speed mode with the ecu inputs to relays 1,2 and 3 all grounded (simulating high speed mode).

I have personally used this method to test low/medium but not high speed mode. I have also included the lowspeed.jpg photo for extra info. See the resources section for the relay info:http://www.fordmods.com/documents.php?d=54

The wires you want to avoid are any thicker wires and also Red/Green trace. Red/Green trace is the 12V supply to each relay and you will blow a fuse (Auto TX fuse)if you ground those wires out (left side of each relay block. see photo). The wires you are looking for are: Relay 1 Yellow/Red trace: Relay 2 Blue: Relay 3 Blue: Relay 4 Blue/white trace.

 

 

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As mentioned many times before fans wont go into high speed until coolant temp is 106*c this is almost to the end of the normal scale on the temp gauge. this is normal operation.

If ford designed the cooling fans to turn on to faster speed at say 95*c there would have been a lot less head gasket problems.

there is a solution, wire up a switch so you can overide fans manualy search it i beleave i posted up a diagram a few years ago, works well even in the most heavy city driving at very hot temps mine never goes past 93*c

also try disconecting temp sensor bellow thermostat cover while the car is runing fans should go into high speed mode.

Thanks guys for all the input, it seems that i had 2 faulty thermostats that were getting stuck open and the temp would all ways sit around the line under L. so thats that thanks for your input guys.

regards fordisgod

Even if you had dud thermostats, thats still a problem. The fans should go high then.

They should also go high when the car is at temp and the aircon is on.

From memory, there is a later revision of EF/NF ECU that fixed this. The original ECU's were a bit conservative as to when the fans were turned on high.