2005 Jetta (older, like 2004), 90,000 miles... large radiator fan (driver's side) isn't coming on anymore - overheating. Probably just the switch off the radiator? Where's the "module" I've read about... is that likely? Are the motors known to go bad?Thanks
The fan motors are a common failure. A quick way to check them is to tap on the motor when they should be running (such as with the A/C on). If it comes to life you know the motor is bad.The module is located below the battery as seen from underneath the car. I doubt it is the cause of a single fan motor not working.Depending on the severity of the overheating problem the fan may or may not be the cause. Water pumps are a common failure that cause severe overheating.Here is an easy check to see if the water pump is pumping.At the overflow tank remove the cap and disconnect the small hose at the top and hold it over the opening of the tank. Have a second person start the engine and hold the rpms around 2k. You should have a strong steady flow otherwise you probably have a bad water pump.
Thanks,Yeah, I already went though the whole water pump problem at 53,000 miles... replaced it with one that had a METAL impeller that wouldn't fall apart! (Really frustrating... 3,000 miles after the warranty expired, nearly destroyed the engine when the timing belt went slack because the plastic impeller disintegrated.)We can only drive it a few miles (from cold) before the temp. is up to the red.So, your order of most likely to fail is 1) motor, 2) switch, 3) module (not likely)Anything else? Thanks.
That sounds about right so far.If it is overheating while the car is moving this can not be caused by the fans. The fans don't make any difference when the car is moving.I would perform the water pump check even though your water pump is probably working. Sometimes the remaining bits of the old plastic impeller can block the coolant passages.Check if there is excessive pressure in the cooling system. Check this by removing the cap (releasing the pressure), then reinstalling the cap, start and run the engine for 30 seconds, remove the cap again. If there was significant pressure released you may have a blown head gasket.Also check the thermostat. If it is stuck closed it could cause the car to overheat. This can be done by monitoring the temperature of the radiator hoses. The thermostat is on the front of the block near the water pump.
Okay, one more thing (thanks for your time!):I should have said, I figured it was the fan because the large one isn't running even when the engine temp. is really getting up there. The small fan is running. Just wondering, too; I assume that they are set for different temperatures, and one comes on before the other? If so, which one first?
They have 2 speeds and they both should be on at the same time.
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