I have a 2006 convertible base with MT without mods and it recently overheated briefly when i was in idle waiting for someone for about 15 min on a hot day (there was no other load on the car, no AC etc). There was also a brief grinding noise when i started moving (sounded like i was dragging a plastic peice under the car). It took me a minute to figure out the coolant temp was pegged on red and flashing. I turned off the engine and found the engine bay very hot. I let the car sit for about 15 min and it cooled down to the normal operating temperature. The car seem to function fine on the way hoe, and I was able to get home with the temp guage in the middle.

Ive been able to trace it down to a non functioning radiator fan. It seems as if it doesnt go on at all, neither the low speed (which should come on around 105 as far as i understand) nor at the high speed when the temp gets hotter. I had the AC running, but the fan still didnt come on. I had the car hooked up to a bluetooth scan tool to watch the temp. AC ran cold initially, then as the car started runing hotter, no longer blew cold air. The temp started moving up around mid one-teens, so i shut the car off, cooled it off a bit, turned off the AC and drove home. As far as I can tell, the radiator fans never came on.

The fuses all seem OK. The Power steering fan seems to function fine (It was seized/gummed up when I first got it, but I cleaned it up a few years ago when i got the car and functions fine since). The rest of the car all seems to function ok. The radiator fan also seems to spin freely when I poke it with a screwdriver. There has been no work done on the car recently *especially with cooling system). Coolant level slightly above min level in coolant resevoir. No engine codes or lights present. TBH, im not even sure when this problem cropped up - since i rarely sit in extended traffic or drive for any signficant distance. Usually it is a commuter vehicle where I drive maybe 10 miles on the freeway with minimal stop and go. Othertimes we might take it 20 or 30 miles away, all freeway with minimal stops. (these conditions may not have been enough to drive the coolant temp hot enough to budge the temp guage).

My understanding is that the much maligned low speed resistor only affects the low speed, and at higher temps, the fan should come on at high speed?

what is the best way to troubleshoot it next? I have limited experience with the cooling system and testing sensors/electrical relays.
I tried searching, but was unable to make much sense of it as much of it seemed dedicated to the low speed resistor problem.


thanks for any help!

 

you may have lost low speed a while back and fan was always running on high .. and now you've lost that too .... not that unusual .....

 

What is involved with losing the high speed fan? (ie: what usually fails, fuse, relay, etc?)

I am starting the trouble shoot process - im getting 11.7V to 2 of the slots at the fuse box for relay 3 and relay 4 (when the ingition is turned on). So it seems the relays are getting powered.

There is also continuity when I connect one of the leads from the relay socket and the plug that inserts into the radiator fan.

The relays click when I apply 12V into both relays

I haven't been able to get a 12V power source / some aligator clips to test the fan themselves. (what is the right procedure? where do the + and - leads connect into the 3 pins on the fan?) There is a brown wire and one that is for the high/low speed (i thnk can figure out which one by seeing which one has positive continuity with the relay terminal)

Once I get the right clips and if the 12V to fan doesnt turn the fan on when I touch the low speed lead (Im guessing Relay 3, labeled as fan I is for low speed and Relay 4 labeled fan II is for high speed?), does that mean the low speed resistor is out?

Do I just replace the low speed resistor? What makes the high speed fan go on?