Cooling fan always runs full speed

[tmurph05]

Hi,

I'm new to volvos and servicing them. I recently noticed my electric cooling fan (right in front of the motor) is constantly running while I am driving. The a/c is off (at least the light is and the compressor doesn't seem to be engaging) and it is also winter here. What could be causing my electric fan to run all the time and how can I fix it? Thanks!

[dpaton]

Please add your model year (MY) to your signature to get better help to your questions.
Find the wiring diagram for your MY - http://www.volvowiringdiagrams.com/?...ing%20Diagrams
The fan relay is in the fan housing and fed by the thermostat temp sensor if I remember.

[tmurph05]

How do I add my model year as a signature? I can type it in every time, but isn't there a way to make it automatic? In the meantime my model is a 2005 Volvo XC 70.

[tmurph05]

I tried to look up the info I need in the wiring diagram.. It was like trying to read hieroglyphics haha.. Any hints on interpretation of those diagrams?

[ssicarman]

How do I add my model year as a signature? I can type it in every time, but isn't there a way to make it automatic? In the meantime my model is a 2005 Volvo XC 70.

Upper right corner of any page is a link button labeled "settings". Click on it. Left side of the page is a box labeled "My Settings". In it is a link button labeled "Edit Signature". Click it and write in what you want your signature to read. Click on the save signature link button. You should now have your signature.

[dpaton]

See the first two pages (144-145) and page 6 for MY2005 to help understand.


On page 59:
Connection 1 is ground, 2 is fan voltage (from 11A/8 (in Engine Compartment)/Fuse 8), 4 is signal from the ECM (computer) to turn ON (12v).

If voltage at 4, then multiple inputs come to the computer through 7/16 (coolant sensor) and 7/8 (A/C pressure sensor) but the likely one was the thermostat temp but that's used by the gauge too (and you would have mentioned that it read wrong (too high)).

If no voltage at 4 (on 4/71 - cooling fan module) yet fan runs, then circuit is stuck ON and since module is not available as a separate item (it's part of the fan housing) then visit auto-recycler or your local stealer.


Normal operation is when fan is not running and engine is at normal temp and thermostat connector is disconnected, the temp gauge will start to rise (about 20 seconds) and the fan will start to run.

[tmurph05]

The problem turned out to be the air intake temperature sensor. It was reading significantly higher than it should and after clearing all the codes, it was the only one that came back. I have the part on order (80$) and will post back if that isn't the problem. But, by going through all the other typical problem areas and eliminating them as possible answers, this is the one that makes the most sense. Thanks!