Hi guys, I am new to this forum but not with working on cars. I friend of mine has an 02 MCS and last Saturday the coolant fan started running all the time, even with the ignition off. It would have run until the battery was dead if she had not unplugged the battery. So her boyfriend and I started looking online and we came to the conclusion that the whole fan/shroud assembly must be replaced, because several people have had this problem.

Jump to last night, I replaced the fan and as soon as we plugged the new unit in the fan started running again, just like the old fan. So my question is, what else controls the operation of the fan. A coolant temp sensor? What else should I be looking at? And where is it located?

It seems that this is a common enough problem and that everybody has resolved it by replacing the fan, is it possible that the new fan was faulty from the get-go? Any other thoughts would be appreciated.

Edit* Forgot to add, after I reassembled everything I topped off with coolant/distilled water and bled the whole system so it is definitely not low on coolant.

Thanks.

 

Might be a bad relay... On the '02's it was on the fan....so check to be sure you got the right fan...I think the relay was moved off the fan, resulting in a new part number in '03. If you have the correct fan, and the new fan does the same thing as the old fan....bad news... Time to look elsewhere. The fans are a weak spot and replacing it was a good idea...but it must be something else. Might be time to get some professional advise and pay for an hour of trouble shooting.....maybe some else has had the same problem.. Try the search function, I'm sure you will find a weath of info, both to act as a well informed consumer, and you might read a thread and find an answer before you get a good reply!! Either way, keep your thread updated!!

 

Update....another user had a similar problem, it turned out that a preasure switch was not connected or bad on the ac compressor....do a quick search....I think it was sockerbum or something that found the solution.

 

Thanks, I haven't looked at the car in a week, but I believe I am going to spend some time tomorrow going over it again. I'll check out this pressure switch. Thanks.

 

Found the link. This problem doesn't sound the same, but I will definitely check into it.

I think we may have received the wrong fan last week, the one we got only has 1 connector, but the original one has 2. We are getting a new one tomorrow and I will hook it up and see what happens. Hopefully the correct fan fixes the problem.

I'll keep this thread updated.

https://www.northamericanmotoring.co...all-wierd.html