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7 Series - E38 (1995 - 2001)

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  #1  
Old 06-23-2014, 09:37 AM
doug powell doug powell is offline
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1995 e38 cooling fan not turning on

Hello all... What's the best way to diagnose what is truly not functioning on a '95 e38 aux cooling fan? the fan will not turn on at all even with a/c on. I heard if refrigerant was low it wouldn't work what has been the experience of those that have had this issue,
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  #2  
Old 06-23-2014, 09:30 PM
Mayorchuck Mayorchuck is offline
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Is your outside (ambient) temp correct on the dash or does it read -40? Checked Fuse 9?
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  #3  
Old 06-24-2014, 05:36 AM
doug powell doug powell is offline
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ambient temp

yes ambient temp is correct
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  #4  
Old 06-24-2014, 05:45 AM
doug powell doug powell is offline
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#9 fuse

fuses are good.
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  #5  
Old 06-24-2014, 01:22 PM
miguel740i miguel740i is offline
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Resistor or the relay is fried
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  #6  
Old 06-24-2014, 01:32 PM
chrisn7 chrisn7 is offline
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Extract from the WDS:

"Auxiliary fan stage 1
The air conditioning system cuts in stage 1 of the auxiliary fan by means of relays when the compressor clutch is active and the outside temperature is greater than 10 o C. The auxiliary fan cuts out when the compressor clutch has switched off or the outside temperature is less than 8 o C.

For safety reasons, a thermostat switch also causes stage 1 to cut in at a temperature of 91 o C irrespective of the instruction given by the air conditioning control unit."

So are you certain the A/C compressor is kicking in? For example, another extract:

"Pressure switch
The triple pressure switch opens the power circuit to the electromagnetic clutch when the refrigerant pressure drops below the value set for low pressure or exceeds the value set for high pressure."

So if the system is low on gas, pressure switch doesn't close; compressor doesn't operate; aux fan won't kick in..
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  #7  
Old 06-24-2014, 05:18 PM
doug powell doug powell is offline
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Quote:
Originally Posted by miguel740i View Post
Resistor or the relay is fried
relay and resistor are you referring to the interior blower motor or to the electric radiator cooling fan.
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  #8  
Old 06-24-2014, 05:23 PM
doug powell doug powell is offline
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Quote:
Originally Posted by chrisn7 View Post
Extract from the WDS:

"Auxiliary fan stage 1
The air conditioning system cuts in stage 1 of the auxiliary fan by means of relays when the compressor clutch is active and the outside temperature is greater than 10 o C. The auxiliary fan cuts out when the compressor clutch has switched off or the outside temperature is less than 8 o C.

For safety reasons, a thermostat switch also causes stage 1 to cut in at a temperature of 91 o C irrespective of the instruction given by the air conditioning control unit."

So are you certain the A/C compressor is kicking in? For example, another extract:

"Pressure switch
The triple pressure switch opens the power circuit to the electromagnetic clutch when the refrigerant pressure drops below the value set for low pressure or exceeds the value set for high pressure."

So if the system is low on gas, pressure switch doesn't close; compressor doesn't operate; aux fan won't kick in..
do you know the part number or location of the relay, or pressure switch. i have a feeling it has no refrigerant in it at all
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  #9  
Old 06-24-2014, 05:26 PM
doug powell doug powell is offline
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the compressor is turning on
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  #10  
Old 06-24-2014, 05:39 PM
doug powell doug powell is offline
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on the .95 e38 the fan switch is on the passenger side of the radiator tank correct. (anyone know)
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  #11  
Old 06-24-2014, 06:00 PM
Mayorchuck Mayorchuck is offline
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Looks to be on your car, yes. Dual temp switch with 3 pin connector. Here is the WDS if you want to dig around a little. Requires JAVA and I had to add an exception for the site in the Java control panel.

http://www.bmw-planet.com/diagrams/r...8old/index.htm
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  #12  
Old 06-25-2014, 11:26 AM
miguel740i miguel740i is offline
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Quote:
Originally Posted by doug powell View Post
relay and resistor are you referring to the interior blower motor or to the electric radiator cooling fan.
The one to the cooling fan
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  #13  
Old 06-25-2014, 11:51 AM
doug powell doug powell is offline
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ive found the relays behind the glove box the switch on the radiator and the temp sensor on lower hose where is the resistor? have you had cooling fan issues? if so what was your cure?
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  #14  
Old 06-25-2014, 01:24 PM
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BMWFatherFigure BMWFatherFigure is offline
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Resistor is on the fan frame (IFRC). To test it: Link out the plug with a short piece of wire. If it refuses to start check if the motor is siezed and the relays etc. If it runs its the switch...
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  #15  
Old 08-29-2014, 08:48 AM
injuhneer injuhneer is offline
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I have a been reading about the E38 aux fan failure.

My 04/1998 car has he 4 pin, 3 speed fan but all the info I have found indicates that fan was not used until 08/1998.

Is this the same 4 min 3 speed aux fan used on the E39?

Any idea how often the fan failure is a case of spent brushes in the motor rather than other failure?

More importantly, are there still replacement motors available for less than value of the car?

I have also read about a replacement using a Volvo 850/960/V70 fan.

-Mike O
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Last edited by injuhneer; 08-29-2014 at 09:12 AM.
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  #16  
Old 08-31-2014, 08:13 AM
injuhneer injuhneer is offline
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So after lots and lots and lots of reading on this subject here is my proposed solution:

Graft a better (commonly available known brand, less expensive) fan onto the BMW mount. Possibly two smaller fans if they will fit with a custom mount.

Add two resistors and 3 steering diodes to produce L-M-H fan speeds.

Install.

Never pay for another fan.

:-)

-Mike O
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Last edited by injuhneer; 08-31-2014 at 08:17 AM.
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