87 300e aux fan not working right.
Thread Starter
Newbie
Joined: Jun 2007
Posts: 7
Likes: 0
87 300E
87 300e aux fan not working right.
so the electric fan in front of the radiator has recently decided to not come on when its supposed too. its not a big deal until i get stuck in traffic and it doesnt come on and my car starts heating up( past 100c). i rigged it up with a switch strraight to the battery and it works fine but id really like it to work on its own.
could it be the engine temp sensor or a relay or what?
thanks for any help or advice you guys have.
could it be the engine temp sensor or a relay or what?
thanks for any help or advice you guys have.
Super Member
Joined: Feb 2003
Posts: 523
Likes: 1
From: Hollywood North
CLK 55 ///AMG Cabrio, ML63 ///AMG
Hopefully this may help someone who has this problem today:
TO CHECK TO SEE IF BOTH AUXILIARY FANS ARE WORKING DO THIS TEST:
Step 1 - With the car off, insert key and turn ignition to the second position where the lights are lit up on the dash.
Step 2 - Press and hold both "Auto" buttons on the Climate Control unit for approx. 10 seconds and then let go (Try it again at 15 seconds if this test does not work the first time with 10 seconds).
- Both Black Auxiliary Fans should turn on and spin.
If only one fan spins, you may have a problem with the fan itself, the fan relay or a circuit to the fan. The chances that both fans do not spin during this test is very slim as both fans should not break around the same time.
The issue that I had was that the Driver's side Auxiliary Fan was shot and did not spin during the test. The Passenger side auxiliary fan was spinning. So, I swaped out the driver's side fan and viola. Fixed - spins. Comes on at approx. 103 cel and shuts off at 98 cel.
Another tip if your car starts to overheat while driving is to manually turn on the fans by doing Step 2 above while driving - this can save your engine/head gasket. My stealership thought that it was the viscous fan clutch and recommended that I change that, the Fan Relay, Thermostat and flush the coolant and then change the Coolant Sensor if the problem was still there. That easily would have been $600-$800. Morons.
Hope that this helps someone.
TO CHECK TO SEE IF BOTH AUXILIARY FANS ARE WORKING DO THIS TEST:
Step 1 - With the car off, insert key and turn ignition to the second position where the lights are lit up on the dash.
Step 2 - Press and hold both "Auto" buttons on the Climate Control unit for approx. 10 seconds and then let go (Try it again at 15 seconds if this test does not work the first time with 10 seconds).
- Both Black Auxiliary Fans should turn on and spin.
If only one fan spins, you may have a problem with the fan itself, the fan relay or a circuit to the fan. The chances that both fans do not spin during this test is very slim as both fans should not break around the same time.
The issue that I had was that the Driver's side Auxiliary Fan was shot and did not spin during the test. The Passenger side auxiliary fan was spinning. So, I swaped out the driver's side fan and viola. Fixed - spins. Comes on at approx. 103 cel and shuts off at 98 cel.
Another tip if your car starts to overheat while driving is to manually turn on the fans by doing Step 2 above while driving - this can save your engine/head gasket. My stealership thought that it was the viscous fan clutch and recommended that I change that, the Fan Relay, Thermostat and flush the coolant and then change the Coolant Sensor if the problem was still there. That easily would have been $600-$800. Morons.
Hope that this helps someone.
MBWorld Fanatic!
Joined: Feb 2007
Posts: 1,297
Likes: 1
From: Connecticut, New Haven
95' AMG SeeThreeSix
Hopefully this may help someone who has this problem today:
TO CHECK TO SEE IF BOTH AUXILIARY FANS ARE WORKING DO THIS TEST:
Step 1 - With the car off, insert key and turn ignition to the second position where the lights are lit up on the dash.
Step 2 - Press and hold both "Auto" buttons on the Climate Control unit for approx. 10 seconds and then let go (Try it again at 15 seconds if this test does not work the first time with 10 seconds).
- Both Black Auxiliary Fans should turn on and spin.
If only one fan spins, you may have a problem with the fan itself, the fan relay or a circuit to the fan. The chances that both fans do not spin during this test is very slim as both fans should not break around the same time.
The issue that I had was that the Driver's side Auxiliary Fan was shot and did not spin during the test. The Passenger side auxiliary fan was spinning. So, I swaped out the driver's side fan and viola. Fixed - spins. Comes on at approx. 103 cel and shuts off at 98 cel.
Another tip if your car starts to overheat while driving is to manually turn on the fans by doing Step 2 above while driving - this can save your engine/head gasket. My stealership thought that it was the viscous fan clutch and recommended that I change that, the Fan Relay, Thermostat and flush the coolant and then change the Coolant Sensor if the problem was still there. That easily would have been $600-$800. Morons.
Hope that this helps someone.
TO CHECK TO SEE IF BOTH AUXILIARY FANS ARE WORKING DO THIS TEST:
Step 1 - With the car off, insert key and turn ignition to the second position where the lights are lit up on the dash.
Step 2 - Press and hold both "Auto" buttons on the Climate Control unit for approx. 10 seconds and then let go (Try it again at 15 seconds if this test does not work the first time with 10 seconds).
- Both Black Auxiliary Fans should turn on and spin.
If only one fan spins, you may have a problem with the fan itself, the fan relay or a circuit to the fan. The chances that both fans do not spin during this test is very slim as both fans should not break around the same time.
The issue that I had was that the Driver's side Auxiliary Fan was shot and did not spin during the test. The Passenger side auxiliary fan was spinning. So, I swaped out the driver's side fan and viola. Fixed - spins. Comes on at approx. 103 cel and shuts off at 98 cel.
Another tip if your car starts to overheat while driving is to manually turn on the fans by doing Step 2 above while driving - this can save your engine/head gasket. My stealership thought that it was the viscous fan clutch and recommended that I change that, the Fan Relay, Thermostat and flush the coolant and then change the Coolant Sensor if the problem was still there. That easily would have been $600-$800. Morons.
Hope that this helps someone.
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Junior Member
Joined: Jan 2010
Posts: 20
Likes: 0
From: Chile
1993 300D turbo
Auxiliary fan not working
This tip is fantastic!
Thank you much.
Is that tip somewhere in a manual?
OldBeaver
Thank you much.
Is that tip somewhere in a manual?
OldBeaver
Hopefully this may help someone who has this problem today:
TO CHECK TO SEE IF BOTH AUXILIARY FANS ARE WORKING DO THIS TEST:
Step 1 - With the car off, insert key and turn ignition to the second position where the lights are lit up on the dash.
Step 2 - Press and hold both "Auto" buttons on the Climate Control unit for approx. 10 seconds and then let go (Try it again at 15 seconds if this test does not work the first time with 10 seconds).
- Both Black Auxiliary Fans should turn on and spin.
If only one fan spins, you may have a problem with the fan itself, the fan relay or a circuit to the fan. The chances that both fans do not spin during this test is very slim as both fans should not break around the same time.
The issue that I had was that the Driver's side Auxiliary Fan was shot and did not spin during the test. The Passenger side auxiliary fan was spinning. So, I swaped out the driver's side fan and viola. Fixed - spins. Comes on at approx. 103 cel and shuts off at 98 cel.
Another tip if your car starts to overheat while driving is to manually turn on the fans by doing Step 2 above while driving - this can save your engine/head gasket. My stealership thought that it was the viscous fan clutch and recommended that I change that, the Fan Relay, Thermostat and flush the coolant and then change the Coolant Sensor if the problem was still there. That easily would have been $600-$800. Morons.
Hope that this helps someone.
TO CHECK TO SEE IF BOTH AUXILIARY FANS ARE WORKING DO THIS TEST:
Step 1 - With the car off, insert key and turn ignition to the second position where the lights are lit up on the dash.
Step 2 - Press and hold both "Auto" buttons on the Climate Control unit for approx. 10 seconds and then let go (Try it again at 15 seconds if this test does not work the first time with 10 seconds).
- Both Black Auxiliary Fans should turn on and spin.
If only one fan spins, you may have a problem with the fan itself, the fan relay or a circuit to the fan. The chances that both fans do not spin during this test is very slim as both fans should not break around the same time.
The issue that I had was that the Driver's side Auxiliary Fan was shot and did not spin during the test. The Passenger side auxiliary fan was spinning. So, I swaped out the driver's side fan and viola. Fixed - spins. Comes on at approx. 103 cel and shuts off at 98 cel.
Another tip if your car starts to overheat while driving is to manually turn on the fans by doing Step 2 above while driving - this can save your engine/head gasket. My stealership thought that it was the viscous fan clutch and recommended that I change that, the Fan Relay, Thermostat and flush the coolant and then change the Coolant Sensor if the problem was still there. That easily would have been $600-$800. Morons.
Hope that this helps someone.
Junior Member
Joined: Sep 2010
Posts: 20
Likes: 0
From: SF Bay Area
1998 E300 TD
Thank you for this tip, the test worked. My problem is the aux fans have not been going to high speed and the car overheated. The test triggered the fans to cycle ... from stop, start to accelerate, then stop and repeat. The highest speed achieved is better than before though. Any thought ?
Thank you much,
hikingmapa
Thank you much,
hikingmapa
Newbie
Joined: Jun 2013
Posts: 6
Likes: 0
1987 300e
In my '87 300E, there's a .2-ohm resistor just below the left headlight housing. It's a tan, rectangular thing with 2 wires screwed into it (one at each end). It was cracked (and fell apart completely when I removed it.) Replacing this very inexpensive part, if it's worn/defective is a good idea. It was in series with the fan...
