To fix the dead Air-conditioning I replaced one of the hoses (which was leaking from the valve) the radiator and drier.
Mobile Aircon guy comes round yesterday and pressure tests the system, which passes: evacuates it and refills.
All good.

(If the dryer had been replaced at some point they must have employed a bodybuilder with a steroid problem to refit it - the nut on the long hose was torqued to the max. Buying a split ring spanner was the best thing I did)

However he notes that the High Pressure side is getting up to 22 bar and only dropping back when the lower cooling fan kicks in. He said that this is probably stressing the system unnecessarily and suggests doing a mod where the lower fan is always switched on when the AC switch is on. Says he has worked on a lot of XJ6s in the past (he's an older guy - actually worked at Jaguar in the past) and this is a common mod using a relay to feed the fan.

I'm sure I remember reading that permanently-on fans became a Jaguar change at some point and shouldn't my 1997 X300 already have it ?
The fan is cycling in and out so it's working fine.
Any thoughts ?

 

BOTH fans run together!!!!!!!!! There is NO normal situation where only one fan runs (unless one fan is inop or the one fan fuse is faulty).

They run in series on LOW and parallel on HIGH.

There was a modification 'back-in-the-day' to run the fans whenever the key was on.

bob

 

Thanks for the reply.

Both fuses are good.
I've been all over page 26 of the X300 1997 Electrical Guide which is "Relay and Fuse Box Identification and Location" - I can't find the Relays for the fans.

I read the Single Pressure switch Modification Bulletin - mine has a wire loop instead of the Single Switch which should mean the fans are permanently on Low - they aren't.
The lower one only is cycling on High presumably when the refrigerant pressure switch is triggered.

 

By coincidence I had exactly the same issue last week. Turned out the relay had died.

I pulled it apart and cleaned contacts but still no good. I had a spare in parts pile and swapped that in. All good again.

Relay is here behind front bumper left hand side. It's a unique relay and can't be swapped with anything else.

 

bloody hell -

COOLING FAN RELAY
X300 XJ6 XJ12 & XJR 1995 to 1997
Part No. LNA6702AB

• £72.36

Still have the puzzle of the single fan operation but will pull the relay off and have a look

 

Your single fan operation with the AC on may be because your car may not have been modified yet . If not it may be fine in the AC mode of operation ( not the coolant Temp mode of operation ) as the TSB wiring mod addresses a low reliability issue with the 4 wire high pressure AC both fan command on switch . As long as your low pressure switch works at this time you are good in a lower cooling demand environment .

To test that the Fans Control Relay Module works along with the 2 fans you would test it in the coolant temperature mode . This test does not test the AC mode of fan operation .

The following paperclip test is a low current control circuit so no high current danger .

Pull the 3 wire connector on the temperature switch on the aft lower left side of the radiator and take a paper clip to jumper one white wire to the black ground wire . This will get you 1 or 2 fan operation . Pull the jumper and go to the other white wire to the black wire and that will get you the other 1 or 2 fan operation .

To test the 2 wire low AC pressure switch just pull the connector and jumper the pins . This will give you 1 or 2 fan operation depending on the status of whether the TSB mod was done .

To use a black X308 Fan Relay Control Module instead of the white X300 you would wire the connector like this . My mom says I need to put the drawing back on her refrigerator because she's very proud of me . The left and right fans will be swapped in how they run but will have the same cooling effect .

My white X300 relay was full of water and damaged beyond repair as I sawed the plastic housing apart so was bad , but don't do that to yours .

 

My ac fan switches look like this.
Is the wire loop replacing the 2 wire low AC pressure switch ?

 

The loop would have the single fan operating at all times . Without looking at the TSB details , this I don't believe this was the Mod , I can be wrong . Mine was never modified . But you are missing the low pressure switch next to the 4 wire high pressure switch . In reality if you have the single fan running in the AC mode you are good up to the point of high AC cooling demand at a stop light .

Verified 2 fan operation in the coolant temp mode ? Easy test .

Cutting grass now .

 

"The loop would have the single fan operating at all times"

Not correct - see Bob's post #2



"this I don't believe this was the Mod"

Yes that is the mod.

 

Fuses :

Right fan and relay control , # 11 / 30 amp green LH engine fuse box

Left fan , # 17 / 30 amp green LH engine fuse box

 

Update

Took the complete fan shroud out to test them - surprisingly simple.
Using an old spare motorcycle battery I could make both fans spin when 12V is supplied.
So I have now ordered a new (used) relay.

 

So there I waaaaaaaaaas .

Had my fan control relay installed but hanging upside down by the wires . Felt warm to the touch so in investigating would shake it and was full of water on the inside of the relay itself . My original relay was also full of water and damaged beyond repair as I cut the plastic housing off .

Make sure you install it in the proper orientation and have the square seal in place .

 

I am struggling to solve this.

The original relay was bad - the low speed/serial magnetic switch didn't work but the high speed/parallel did.
The new (used) relay tests OK on both switches.
But I still get the same symptoms:

1. NO fan running with engine on until (presumably) the high pressure switch trips and then the LH fan ONLY comes on.
2. Take the fans out of the car and apply 12V and both fans spin easily .
3. Both fuses good

There is 12V getting to the purple wire attached to the RH fan (using the earth point on the bulkhead behind the refrigerant switch)


With reference to fig 7.1 of the 1997 Electrical Guide I removed the relay and tested the sockets on the relay connector.
Pin 2 goes to the local earth so I tested voltages against this.
Fuse 11 feeds Connectors 73 and 74
Fuse 17 feeds Connector 76

The connector 76 from the fuse feeds Pin 5 - I got 12V.
At pin 6 from connector 74 (feeds the two switches in the relay) - 12V.
At pin 3 from connector 73 but through the RH fan I got 4V but I guess the load of the fan distorts this ??

Tested continuity from pin 2 (local earth) to pin 8 (low pressure switch or in my case wire loop) - switched ignition on and zero ohms.
As this feeds a switched earth - this is what you would expect - so the earths in the engine bay seem to be connected.

The replacement relay is LNA6702AA rather than the original LNA6702AB but I don't think this relevant.

Did an extra test - pulled the radiator 3 pin plug and connected the black in turn to the 2 white wires - same result, no slow running, fast running on LH fan only.

What have I missed ?

 

The relay part # is important and I'll verify your numbers . A same looking X308 relay will plug in but not work in a X300 .

 

Think I've found a smoking gun.
Tested for resistance between the black and white wire on the RH fan and pin 3 on the relay socket.
Got no continuity so I will pull the connector above the relay - I think it passes through this.

 

LJA 6707 AA will not work unless the harness is rewired .

Let me know your results .

 

I get continuity from the fan to the intermediate connector above the relay.
But not from the other side of that connector to the relay socket.
I noticed some electrical tape covering this:

 

There are some factory wire splices that have heat shrink covering them .

The only wire on mine with a factory splice at the 4 wire connector is the Black / White wire .

Let us look over your previous post findings . How bout that bowl of spaghetti inside the relay !

Bring the right fan connector over to the left fan and do the radiator switch black to one of the white wires one at a time . This verifies the right fan does not work and your relay circuits are good .

 

If it's not the relay, the fans or the fuses then it has to be the wiring.
And so it proves.

I've fixed it.
Replaced a section of the Black and White wire leading from the RH fan to Pin 3 of the relay. Bypassed the 2 connectors and all is well.

Both fans on low when I turn the ignition on and if I use a wire on the radiator 3 pin connector I can make both fans spin fast.
I'm going to have a large ice cold beer.

 

There is no low or high speed fans on the X300 as the fans are either on or off . The low cooling demand fan is the left one and when high cooling demand is required it adds the right fan . The X308 is opposite .

Inside the relay there are 3 relay contacts and one or more may be compromised by pitted power contacts .

You may also be seeing the difference in voltage spinning them up faster between only using the battery as a power source and the higher voltage coming from a spinning alternator .

Not time yet .