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1987 300TD
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11 Posts
Discussion Starter #1
the issue i'm having is that i can't get the fans to come on whenever i cut the ac system on and thus get a mediocre air coming from vents.

i've checked the 15a fuse on the relay right in front of the firewall. i've also checked the relay itself that it does switch on/of and when on has continuity.

is it possible to bench test the air dryer or test it while on the car? the dryer itself does get cold when refrigerant in ac system and functioning

whenever i bypass the drier, the fans till won't come on...suspect resistor( is there is way to test it? any ideat what a resistance value would be?)

the fans do work as when i unplugged the hi temp switch on thermostat housing, they run wide open

any assistance would be greatly appreciated
 

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95" W124/ E220 MasterPiece and 01" W210/ E200 KOMPRESSER
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269 Posts
At fan stage one (low speed), the whole circuit needs to go through this "resistor" right behind your left lamp.
Testing the resistor is easy....simply test the continuity between the two connecting points of the resistor....

If there is no continuity, you got a broken circuit......bridging two opposite sides of the wire connectors brings your circuit back....but....the fan runs at high speed....cause there is no "resistor" which filters / blocks part of your electricity.
The aux fan will run at full speed.
2636715
 

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Registered
1987 300TD
Joined
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11 Posts
Discussion Starter #4
At fan stage one (low speed), the whole circuit needs to go through this "resistor" right behind your left lamp.
Testing the resistor is easy....simply test the continuity between the two connecting points of the resistor....

If there is no continuity, you got a broken circuit......bridging two opposite sides of the wire connectors brings your circuit back....but....the fan runs at high speed....cause there is no "resistor" which filters / blocks part of your electricity.
The aux fan will run at full speed. View attachment 2636715
Thanks a bunch for the response. You've saved me from an attempted "parts throw" at the car. Well, now I know that the resistor's good, I'm suspecting the dryer sensor is bad.
 
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