: why wont my fans work?

02-04-08, 06:43 PM
I am not sure if im in the right fourms but I have a 99 sls and my fans wont spin and that causes the anti-freeze and water to spill

02-05-08, 04:43 PM
I'd start by checking the fan fuses and relay in the engine compartment box. If they check out OK then you're going to have to begin checking the fan 12V circuits and temperature sensor.

Can you spin the blades by hand? Does the car boil over only while sitting at idle or all the time? Try to find someone with a handheld infrared thermometer so you can see the temperature at the thermostat housing as the car warms up. How full are you trying to keep the surge tank?

Obviously something is not right, but you'll have to do some hands-on detective work.

02-05-08, 05:29 PM
where are the fan 12V circuits and temperature sensor located cant seem to find them?? Im able to spin the fans by hand, Ive check the fuses, it will stay cool for about 10 15 mins at the most while in park, and im just tryin to have enough anti-freeze in surge tank.

02-05-08, 10:06 PM
The fuse locater is on a diagram stuck to the inside of the fuse box top. There are 2 fuses (fan 1 & 2) and 2 relays.....one for on/off and one for series/parallel. There is a very specific procedure for troubleshooting, and it involves use of a Scan II tool (GM dealer or buy your own for $3,800)

The Engine Coolant Temperature (ECT) sensor is in the front (main drive belt) end of the engine, in the left (front) of the block, behind the belt and a pulley or two. You'll have to remove the right front wheel and inner fender liner to get to it.

I'm not sugar-coating any of the coolant fan troubleshooting: it's fairly technical and depends on a lot of conditions to work correctly.

02-05-08, 11:13 PM
Thanks :highfive: I spent 2 hours lookin for that sensor. And I know you didnt sugar coated and thanks alot for the help now gotta wait till the weekend to get that fix and 3,800 is a little to much.

02-06-08, 06:52 PM
thaish......I just finished surfing my subscription to alldatadiy and discovered that there's an ECT (Engine Coolant Temp) sensor shown in the coolant crossover at the throttlebody end of the engine, just below and to the right of the TB casting. That would put it in the rear right of the engine block area.

That's my '02 engine, but look there first because if you get lucky it's a hell of a lot easier than pulling the fenderwell apart!