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Old 06-11-2005, 01:12 PM   #4
Bill Z
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Join Date: Jun 2005
Posts: 3
Default Re: Wolfman's Guide for Diagnosing the Radiator Cooling Fan

My Saturn is a 99 4 door with 2 OHC. The radiator fan turns on with the AC. Without the AC the car over heats at stop lights.

I used a scanning tool and the 2 wire temp sensor seems to be telling the ECM what the temp is. I can see it going from 80 to 193 degrees over about 10 minutes of idling in the garage. The dash temp gauge only shows 1/4 and never more.

I disconnected the 2 wire sending unit and the temp on the ECM went to something like -40. I reconnected and it displayed a temp. I disconnected the one wire sending unit and the temp gague on the dasy went to zero.

Since the AC makes the fan work, the fan doesn't have a problem. The 30 amp fuse is good. The AC relay is working. The fan relay is working. By the way, I swapped the AC and fan relay just to see. No change.

So, what makes the fan turn on with out the AC on? Where do I check next?
What did I miss?


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