SL/R129: 93 500SL (R129) Auxiliary Fans Problem
12-04-2018, 06:04 PM
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Mercedes 500SL 1993
93 500SL (R129) Auxiliary Fans Problem
Hello All!
I’m having trouble with my auxiliary fans. My R129 runs “HOT” after a while, above 100 temp mark. I noticed that my aux fans don’t stay on as long as they should to reduce temp down to normal operating temperatures. I replaced fan clutch 3 times (just to make sure they weren’t faulty), replaced radiator, water pump, thermostat & did a coolant flush. I tested whether I had a blown head gasket or a clogged cat converter. I also made sure no air got into the cooling system when I did the coolant flush. So, I know that the issue that I’m having is due to aux fans.
I replaced the aux fan “resistor” located underneath the drivers side head lamp, I replaced both temp sensors & the aux fan “K9” relay. I noticed that my aux fans turn on for about 3 seconds & then turn off. They continue to do this from time to time, but eventually they stay completely off. They work fine when I turn on A/C. I did notice however that they don’t hit that second stage of operation when they tend to sound very loud when car is beginning to overheat & if it does it only stays on for about 3 seconds. I also read on another forum that they can hit a 3rd stage of fan speed? But I’m not sure if this is true or not. I’m beginning to think aux fans need “re-programming”
Before this heating issue, my car would always stay between 85-95 operating temps, no matter how hot the summer day weather was & I would hear those aux fans working fine. I know that the aux fans aren’t suppose to stay on “ALL THE TIME” but I also know that they bring down operating temps back to normal when the car is close to reaching above 100 temp.
I was going to replace the aux fan “module” or ESG module located inside drivers side fender well, but I noticed that my car doesn’t have it. Unless, I haven’t found it yet or maybe my car just doesn’t have it. I read on another forum that the aux fan module was introduced in 97, also not sure if this is correct.
Can someone please help me with finding out why my aux fans are behaving this way? Do I have to program the aux fans? Do I have to change a part out? Do I have to replace computer? I appreciate all advice! Thank you!
I’m having trouble with my auxiliary fans. My R129 runs “HOT” after a while, above 100 temp mark. I noticed that my aux fans don’t stay on as long as they should to reduce temp down to normal operating temperatures. I replaced fan clutch 3 times (just to make sure they weren’t faulty), replaced radiator, water pump, thermostat & did a coolant flush. I tested whether I had a blown head gasket or a clogged cat converter. I also made sure no air got into the cooling system when I did the coolant flush. So, I know that the issue that I’m having is due to aux fans.
I replaced the aux fan “resistor” located underneath the drivers side head lamp, I replaced both temp sensors & the aux fan “K9” relay. I noticed that my aux fans turn on for about 3 seconds & then turn off. They continue to do this from time to time, but eventually they stay completely off. They work fine when I turn on A/C. I did notice however that they don’t hit that second stage of operation when they tend to sound very loud when car is beginning to overheat & if it does it only stays on for about 3 seconds. I also read on another forum that they can hit a 3rd stage of fan speed? But I’m not sure if this is true or not. I’m beginning to think aux fans need “re-programming”
Before this heating issue, my car would always stay between 85-95 operating temps, no matter how hot the summer day weather was & I would hear those aux fans working fine. I know that the aux fans aren’t suppose to stay on “ALL THE TIME” but I also know that they bring down operating temps back to normal when the car is close to reaching above 100 temp.
I was going to replace the aux fan “module” or ESG module located inside drivers side fender well, but I noticed that my car doesn’t have it. Unless, I haven’t found it yet or maybe my car just doesn’t have it. I read on another forum that the aux fan module was introduced in 97, also not sure if this is correct.
Can someone please help me with finding out why my aux fans are behaving this way? Do I have to program the aux fans? Do I have to change a part out? Do I have to replace computer? I appreciate all advice! Thank you!
