2000 Buick Century. Started out with a blown 25 amp fuse in main fuse box under hood. Replaced fuse and still had no cooling fans.Replaced temp switch and bleed both 8mm bleeders after topping off antifreeze. Ran car till engine got hot and still no cooling fans. Turned key to on position and unplugged wire to temp switch and both cooling fans run. So I know the fuses are good, the relays must be working, both fans are good. What next ??? How do I test the temp sensor ? This is a 3 wire plug sensor. Every thing I find on the internet is on how to test a 2 wire sensor. Anyone here that has had this problem or know how to fix it I could use some help. Even if you can tell me which color wire from the sensor goes where and does what. Also AC has not worked all summer if this may be part of the problem, cooling fans do not come on when switched to AC. Winters here and wife need car running or no pay check.

 

Tough question(s). Can understand about needing car to get to work. Getting cold out, I'd run a separate toggle switch (to inside car) off the battery (w/inline fuse) to power the fans (disconnect existing harness). Not to be done as permanent, only until problem is found. When motor starts running warm switch on fans.

May never even get warm enough to run fans in winter, up in ME anyways. People stick cardboard in front of their radiators. Maybe look for rodent damage, sounds if something chewed wiring and shorted. They love the taste of tape and insulation.

Couldn't be any worse than driving wife's '66 VW and only had the emergency brake handle to stop with when I'd lose brakes lol (early 70's)...... Oh too, look in air filter compartment for food hoarding of mice.

Is it possible also that sensor runs direct from the PCM or engine control module to operate fans? Now those can be costly, check for corrosive or intermittent connections. Ten year or more old car can be putting more money into than it's worth.