I know I have seen information on this while browsing threads before, but now that I need it, I was not able to find it in a search.

The 2 electric fans, the lower, which I assume is controlled by engine temperature, comes on and off just fine. The upper, I guess is for the Air Conditioning, does not come on at all. Warm or Cold, A/C on or off.
I have checked the 2 30 amp fuses on Left front of engine bay, they are good. I could not find any other fuses or relays listed in my Vehicle Care Manual.
I checked the plug on the fan, it is clean and tight.

I do have a spare set to try, but before I remove these, is there any other switches or controls that may affect just the upper fan?

Thanks!

 

The A/C Trinary switch controls a radiator fan (and compressor).

Have you run the climate-control tests? An Error 23 reveals a bad Trinary switch (and/or low refrigerant level).

 

The fans work together. They start in series then transfer to parallel with relays that are on the crush structure on the left side. Engine temperature or AC cause both fans to run. You probably have a bad fan bearing, which causes the other fan to run in high speed even when thay start in series, since the non turning fan's counter emf is zero.

 

OK...the lower fan only comes on with engine heat, not with A/C as it should.
The upper fan never comes on.
The compressor works, the A/C is ice cold, so all is good...except at an extended idle due to the fans not working correctly.

I know which set of relays you referred to, going to go check them, plus see if the upper fan is getting any voltage.
From what you both have said, I am assuming the upper fan is bad either way.
I did not realize they both came on for engine heat.
The water temp stays good even in heavy slow traffic in Florida heat.

Back out to the driveway...Thanks!

 

Thanks!! Your info helped me know what to look for. Upper fan is bad.
All works perfect now.
Thanks again!

 

I just had to add that the circuit diagram for those fans is given on an electrical engineers final exam!! But seriously, those fans are a unique bit of engineering when you can understand the diagram and figure the slow speed and high speed circuits. I would give a copy to all my apprentices and have them figure out slow and high speed circuits. That was all it took to find the good guys versus the ones that needed a different career path. Glad you got it figured out!

 

Glad you got the fans working again.
Just wanted to add that the fan circuit on the X300's should have been modified so the fans always work on low speed unless the engine temp or a/c pressures require high speed. The attached bulletins list fan diagnosis and describe the modification to help prevent blown fan fuses.

Cheers,

 

Here's the wiring diagram for the fans and compressor.