Condenser Fan not working

J

JRAtkins

New member
I've seen a few posts on this subject, but I haven't found exactly what I'm looking for. I have a 1997 NAS Defender 90 with the V8. The condenser fan, or the fan in front of the radiator quit working. I've replaced the fan, I've checked all the fuses, but as the temp goes up, the fan does not come on. I bought a Fan Temperature Switch (PRC3505) from RoverParts, thinking that might work, but it doesn't go where I thought it would (in the thermostat housing) whatever that sensor is, it is much smaller in diameter. I can not find a diagram, and RoverParts couldn't help me figure out where this Fan Temperature Switch might actually go. Any help would be greatly appreciated. I've also bought a fan relay, but that hasn't come in yet, but looking at other posts, that appears to be the middle relay (in a group of 3) that is on the passenger side, to the right of the A/C. Hopefully that helps. But if anyone can help with the location of this sensor/switch, or has any other ideas.... Thanks,
 
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javelinadave

javelinadave

Administrator
Staff member
There is also a trinary switch, STC3976 that I believe sends a signal for the fan to run. Sucks throwing parts at a problem so hopefully one of our resident experts will chime in.
IMG_1257.jpeg
 
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Z.G

Z.G

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The condenser fan can run without the trinary switch functioning if there's a request from the ECM. That scenario happens at 225F+

If below that, the trinary switch could likely be a culprit. As could the relay unless you've confirmed that's functioning
 
jymmiejamz

jymmiejamz

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Callsign: KN4JHI
If the engine fan is moving enough air at idle, the condenser fan will not run because the high side ac pressure will not get high enough to trip the trinary switch which would turn on the fan
 
J

JRAtkins

New member
But like many of these other scenarios, after it has been running a while, the temp gauge shows to be on the hot side, and the fan still does not come on. Where is this Trinary Switch you speak of? Also, I bought a relay off of RoverParts, but the one on my Defender has a center prong, the replacement does not. Did I get the wrong relay, or is it ok to not have that center prong?
 
M

madcowdungbeetle

0
JRAtkins said:
But like many of these other scenarios, after it has been running a while, the temp gauge shows to be on the hot side, and the fan still does not come on. Where is this Trinary Switch you speak of? Also, I bought a relay off of RoverParts, but the one on my Defender has a center prong, the replacement does not. Did I get the wrong relay, or is it ok to not have that center prong?
Click to expand...
My gut tells me you've got the wrong relay. They should be same as far as the prongs go. Even if the PN# is right, then it was probably mislabeled or defective.
 
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