Hi all. First post and first time owner. I'm trying to debug an issue with my cooling fans. They do not come on. I have done a lot of reading through the various threads finding all the good nuggets I believe.

• This car has the pig tail mod so my understanding is the fans should come on when the car is started, but currently they do not.
• I have checked both 30 A fuses (11 & 17) and they are good.
• I disconnected both fans and jumped them with a spare 12 v battery and both spun when given the juice so the fans are good.
• I disconnected the top connector and I have voltage on the purple wire. When I tested ground with the ignition on it showed open.
• I found the earth ground on the left side under the air filter, disconnected the three connections cleaned them and the stud and reassembled. They were just dusty, but cleaned them anyways. I then retested ground and it was still open.

So after all this, is the next logical thing that fan relay has went bad? I'm not sure how the grounding is or is not effected by the fan relay. I did locate the relay, disconnected it and reconnected it but still no success.

• Is there anyway to test the relay?
  • If not, I have part # LNA6702AA (white one), do you know if LNA6702AB can be used as a substitute?
  • I haven't been able to find a decent AA version that didn't have the casing all cracked up but found what looks like a decent AB version.

Last tidbit, my AC does not work currently I have made the assumption that shouldn't matter for low speed fan operation that should be on with the ignition switch.

Thank You All in advance.
John

 

There is one smaller fuse that is the control power to the fan control relay module

Stand by for me to look deeper into your observations

If the fan control module is mounted upside down water can enter messing up the power contacts inside

Connector should be on the bottem

The white version of module is the one that is needed

 

To test the relay as installed remove the 3 wire coolant temp switch connector on the rear lower aft car's left on the radiator

jumper with a paper clip between one white wire and the black

Remove and jumper the other white wire to the same black

Low current so no arcing hazard

On the 4 wire connector on the freon high pressure switch ..................

White / Blue to Black

 

So on the high speed I jumpered the white to black and both fans came on high speed as a pair. It did not matter which black wire I jumpered it to. When jumpered the blue to the black nothing happened. I tried with the key on and off.

I have a question on the temp sensor connector. I am super paranoid about breaking something so I am gonna ask the novice question. How does it come off? Do I pull the metal band on the side to release it?


Does the clip on the left slide?

 

So after a nap ........................

On the 3 wire connector in your pic , you would press in on the metal bar and it will release , if that fails you can just pluck the metal bar off

On the high pressure freon switch you have one set of contacts that controls the compressor clutch

The fan control contacts are the White wire with Blue stripes , there are 2 black wires that both will work as they both go to car frame ground

This High pressure switch will not give you low fan mode

 

So duh on my part for the connector removal. You get something stuck in your head and can't see the obvious which was to squeeze the metal retainer clip. Anyways, jumped the outside white to black and both fans came on (seemed like same speed as the when I jumped the 4 pin one), but got no fans when I jumped the middle white to black. If I'm reading the electrical diagrams correct Pins 1 and 3 are the 100 degrees C switch which matches the high speed fans that I got, and my failed connection pins 1+2 is the 86 degrees C which would be low speed fan. I did measure there is the same voltage on both white pins. So what conclusion can we draw or what would be the next logical check? My guess is the fan control relay is shot, that is if they can half fail. But if there is some other easy things to check I am game, would prefer not buying used parts (they may or may not be good) for the sake of a guess.

 

Do the same test with your replacement fan control module

What is the part # of your replacement module ?

Quick note before Dr. appointment

 

I haven't purchased a replacement yet, was hoping I didn't need to. Currently installed is the original part LNA6702AA, was going to buy part number LNA6702AB if it is compatible and I needed it. The part looks identical other than it being AB and not AA in the part number. Otherwise I need to locate a suitable AA replacement still. John

 

Your voltage on the 2 white wires of the 3 wire coolant temp switch is correct

The voltage is coming through the fan module as the pulling coils that would separately close the power contacts on the other wires to the fans

The relays inside the fan module .............

Siesta Monster attacked me so waking back up

 

The black fan control module for the later V8 powered X308 is

LJA6702AA

This one operates a little bit different so not to be used

I'll be on dialysis chair for 3.5 hours tomorrow morning so will regroup then

 

Starting look into

Before we start , on M' Lady Penelope the fan control relay module was hanging upside down so water got in it ruining it , you could shake it and hear water in it

After finding a replacement at the salvage yard and coming up with a test what I observed was that left fan only for low mode and both fans for high mode

This is different than Motorcarman ( Bob ) who certainly has more experience than me stating both fans at low speed for low mode and both fans high for high mode

This may be the difference between an AA and AB white fan control relay module

It may have something to do with the TSB that you have the jumper plug on the 2 wire low freon pressure switch ( not the 4 wire under pressure freon switch

In the end we are trying to get your low coolant temp mode ( actually the 86 C which is medium temp) or the jumperd freon low pressure mode

Researching

 

I did buy the AB version today, wasn't able to a locate an internal electrical drawing to confirm it is the "same" as the AA version. Seen some write ups that it was a direct replacement. It won't arrive for a few days. The original was oriented the correct direction hanging by the metal bracket and a pain to get to. The relay's plug was on the bottom.i shook it and couldn't hear any evidence of water. The replacement I bought came out of a 1997 XJ6.

I appreciate the help so far, been fun learning how this stuff works. I anticipate there will be many more things to learn.

 

Wifi back ,

Since you have the shorting plug on the 2 wire connector , this from the TSB

The switch has been replaced by a shorting plug. The cooling fans will now operate continuously at slow speed when the ignition switch is in position II (normal engine running position). This means the 86ºC contacts on the radiator thermostatic switch are now redundant.

 

On the wiring guide the inside of the fan control relay module may not be updated ( if it was changed ) if you can follow that bowl of spaghetti

 

So is the pig tail connection that is tied to the ignition independent of the fan relay then? Any measurements or tests that I can do on the pig tail plug or related wiring? This is what started the adventure because I noticed the fans were not coming on when I started the car.

 

The AB version will be fine. It's a superseded part no.


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Hi All,
A quick update on my cooling fan issue. I received the replacement fan relay switch LNA6702AB and installed it. Initially things didn't appear good until I realized somehow I had drained my battery in this process. I am suspecting I didn't have the trunk fully latched and the trunk lights drained the battery but not certain. But regardless and more pertinent to this conversation once I recharged the battery I flipped the switch "winner winner chicken dinner" I had both low speed fans come on! Thanks to Parker7 for stepping me through all the things to check before buying the replacement relay. I took her for a run and all was well. I also jumped the 4 wire high pressure plug to see the fans transition to high speed and then back to low speed as expected.