Thanks alot,I'll try that,also have a Davies Craig thermo controller that'll be getting installed after some other modifications coming up.

Thanks for all the great advice will be sure to check it out 👌👍😁🍻

EF and EL Thermofans theory of operation.pdf EL Falcon Thermatic Fan Wiring.pdf       Ford BA Falcon, Quick and Easy Modifications The Purpose of this document is to Outline wiring information for the EF/EL/AU/BA and Territory Thermo-fans.
This Document describes fitting and wiring thermo-fans in their respective factory fitted format - (eg, EF fans into EF), and also how to retro-fit thermo-fans designed for different models - (eg, AU Fans into an EF).

The thermo-fan wiring and relay information detailed within this document includes, but is not limited to, EFs 3 Mode (4 Relay) Fan system. ELs 2 Mode (3 Relay) Fan System. AUs 2 Mode (3 Relay) Fan System. BAs 2 Mode (3 Relay) Fan System. EFs 3 Mode (4 Relay Fan System) - Description EF/NF/DF model falcons are fitted with two electric fans controlled by four relays linked to the EEC module.
During Service operations ensure that the fan is not rotated in a direction opposing normal operation as this may damage the motor.
Three operating modes are used (Excluding OFF) depending on the status of the four relays (Determined by the EEC module).
The different operating modes provide different cooling capabilities. Mode FAN SPEED rpm RELAY 1 (N/O) RELAY 2 (N/O) RELAY 3 (N/C) RELAY 4 (N/C) M1 M2 1 Part
1400rpm Part
1400rpm Off Open On Closed Power to M2 Off Closed On Open Diverts Power to M1 2 Full
2300rpm Part
1400rpm Off Open On Closed Power to M2 On Open Power to M1 Off Closed 3 Full
2300rpm Full
2300rpm On Closed Power to M2 On Closed Power to M2 On Open Power to M1 Off Closed EL/AU/BA 2 Mode (3 Relay Fan System) - Description EL/AU/BA model falcons are fitted with two electric fans controlled by three relays linked to the EEC / Visteon Oak module.
During Service operations ensure that the fan is not rotated in a direction opposing normal operation as this may damage the motor.
Two operating modes are used (Excluding OFF) depending on the status of the Three relays (Determined by the EEC /Visteon Oak module).
The different operating modes provide different cooling capabilities.
WARNING - On BA/Territory models, the Fans may start with the ignition in any position !
It is recommended that you disconnect the earth lead on the battery, before servicing the thermo fans! Mode FAN SPEED rpm RELAY 1 (N/O) RELAY 2 (N/O) RELAY 3 (N/C) M1 M2 1 Low Part
1400rpm Part
1400rpm On Off Off 2 Full
2300rpm Full
2300rpm On On On Thermo Fan wiring information
  This section describes the differences in the thermo fan wiring for EF/EL/AU and BA model falcons.
Simply put, the main difference is that the EF model thermo fans have an extra wire (Orange Colour) from the vehicle going to the fan to allow for an extra fan speed for the Right Hand Side Fan.
Because of this, the right hand side fan plug for the EFs (From the fan) has 3 wires going to it (Red, White, and Black).
The Right Hand side plug is the same for all models, and (From the fan) only has 2 wires going to it (Red and Black). Wiring an EF Thermo Fan to an EF
  This information is provided just in case the Fan plugs have been cut or removed, (habib-ed).
The following chart will give you a better description of what wire goes where. Wire Plug Goes to Purpose Black RHs 2 Pin - 2 wires Black Wire on Fan Supplies ground to RHS fan (Permanent) Violet / Yellow Stripe RHs 2 Pin - 2 wires Red Wire on Fan Supplies power to RHS fan via Relay 3 (SPDT) Orange 1 LHs 4 Pin - 3 Wires Red Wire on Fan Supplies power to RHS fan via Relay 1 (SPST) Orange 2 LHs 4 Pin - 3 Wires White Wire on Fan Supplies power to RHS fan via Relay 2 (SPST) Pink / White LHs 4 Pin - 3 Wires Black Wire on Fan Supplies ground to RHS fan via Relay 4 (SPDT)
Or Ground Routed through RHS fan via Relay 3 Wiring an EL/AU/BA Thermo Fan to an EL/AU/BA
  This information is provided just in case the Fan plugs have been cut or removed, (habib-ed).
The following chart will give you a better description of what wire goes where. Wire Plug Goes to Purpose Black RHs 2 Pin - 2 wires Black Wire on Fan Supplies ground to RHS fan (Permanent) Orange RHs 2 Pin - 2 Wires Red Wire on Fan Supplies power to RHS fan via Relay 2 Violet / Yellow Stripe LHs 4 Pin - 2 wires Red Wire on Fan Supplies power to LHS fan via Relay 1 (SPST) Pink / White LHs 4 Pin - 2 Wires Black Wire on Fan Supplies ground to LHS fan via Relay 3 (SPST)
Or Ground Routed through LHS fan via Relay 2 Wiring an EF Thermo Fan to an EL/AU/BA
  The following information is provided, should you only have EF thermo-fans available.
Basically the extra wire on LHS thermo fan (White colour from the fan) is connected to the other power lead (Red Colour from the fan) on the same plug.
You will need to modify the plugs in order for the fans to work.
One way to do this (Not pretty), is to cut the fan plugs off the ends from the vehicle side, and use Female spade connectors, plugging these directly into the fan plugs (on the fan side).
The following chart will give you a better description of what wire goes where. Wire Plug Goes to Purpose Black RHs 2 Pin - 2 wires Black Wire on Fan Supplies ground to RHS fan (Permanent) Orange RHs 2 Pin - 2 Wires Red and White Wire on Fan Supplies power to RHS fan via Relay 2 Violet / Yellow Stripe LHs 4 Pin - 2 wires Red Wire on Fan Supplies power to LHS fan via Relay 1 (SPST) Pink / White LHs 4 Pin - 2 Wires Black Wire on Fan Supplies ground to LHS fan via Relay 3 (SPST)
Or Ground Routed through LHS fan via Relay 2 Wiring an EL/AU/BA Thermo Fan to an EF
  The following information is provided, should you NOT have an EF fan available.
The extra orange wire on for the LHS thermo fan (goes to the White colour on an EF fan) must be connected to the other Orange Fan power lead on the same plug.
This ensures that the fan is powered up regardless of the Fan speed mode required by the EEC. Additionally, you will need to modify the plugs in order for the fans to work.
One way to do this (Not pretty), is to cut the fan plugs off the ends from the vehicle side, and use Female spade connectors, plugging these directly into the fan plugs (on the fan side).
The following chart will give you a better description of what wire goes where. Wire Plug Goes to Purpose Black RHs 2 Pin - 2 wires Black Wire on Fan Supplies ground to RHS fan (Permanent) Violet / Yellow Stripe RHs 2 Pin - 2 wires Red Wire on Fan Supplies power to RHS fan via Relay 3 (SPDT) Orange 1 LHs 4 Pin - 3 Wires Red Wire on Fan Supplies power to RHS fan via Relay 1 (SPST)
2 Orange lines should be connected Orange 2 LHs 4 Pin - 3 Wires Red Wire on Fan Supplies power to RHS fan via Relay 2 (SPST)
2 Orange lines should be connected Pink / White LHs 4 Pin - 3 Wires Black Wire on Fan Supplies ground to RHS fan via Relay 4 (SPDT)
Or Ground Routed through RHS fan via Relay 3 Diagnostic Testing (only EF/EL Models presently) There are 2 methods to diagnose problems with the thermo fan system on EF and EL Model Falcons.
The first method is by far the easiest and trouble free solution, as it does not require diagnostic mode.

Testing the Thermo Fan operation - Easy method 1. Ensure that it is safe to start the engine on the vehicle to be tested. (I.E. no tools in engine bay, etc). 2. Start the engine of the vehicle. 3. For non climate control cars - Turn the Air-conditioning to MAX, and the Fan speed to MAX. 3. For auto climate control cars - Press AUTO, and set the temperature to the lowest possible setting.
Once this has been carried out, the Thermo fans should be running at their High Speed setting.

Testing the Thermo Fan operation - Using the EEC Diagnostic mode. 1. With the Ignition Switch Off, Connect the Engine STI Input to ground, (The STI Input is the First pin from the left, upper row, connect this to the Pin directly below it) 2. Place the gear selector into DRIVE to turn the Thermo Fans On, then Place the Transmission into NEUTRAL to stop Fan operation. For EL Falcons, repeating the Drive to Neutral operation, cycles through the various fan speeds 3. If both fans do not operate, then you may have trouble codes logged within the EEC-V memory. You must clear these codes for the Thermo fan test to work !

EL/AU/BA thermo-fans are two stage - Both Low, or both High In factory format, A/C ON, should force both fans to full speed   See this thread for tech info -   Also see these documents - EL Falcon Thermatic Fan Wiring.pdf EF and EL Thermofans theory of operation.pdf  

I'm not familiar with the fan issues other than I've read that being 20+ years old they can be dead from age/wear now. so testing them individually or checking the wiring would be an easy starting point.   water leaks can be tricky to track down, a tip i was told decades ago was to puff flour around suspect places and it will be washed off if there is a leak. 
don't rule out water doing the capillary action of running down a wire, bonnet cable, etc if the grommet is cracked or just running down the firewall into the brake pedal hole etc (shouldn't but things like that are possible)
also the door seals can be surprising for a leak source, as with windscreen seals. 
the flour test is probably worth doing if you have a suspect spot for leaks.
the air vent is pretty tall, there'd need to be a lot of water in the plenum if it was to overflow that, and if it's been repaired in the plenum they should have seam sealed it otherwise. 
check the plenum isn't full of water due to blocked drains first, that's an easy test also  

@deankxf or @SPArKy_Dave might be able to help with this. I recall one fan came on with A/C and the other was temp sender.??  

Sadly I just hosed the car down & it still leaks, wounder if the water found it's way through top of the vent.  Another simple fix you may be able to help with my Twin AU fans only one was working, perhaps just relay or wiring you think 🤔 

from my understanding the difference between the 94ab and the 94dt (ef xr6 head) was the valve size, pretty sure they had the same port size, but I could be wrong.   I'd assume that fitting the larger 94dt sized valves to the 94ab head would bring it up to the xr6 heads flow rate.   Does any one know what the exact specs of the EA Falcon's cam is?

@Thom any thoughts on VCT heads, AU tickford heads and the XG head above?
  is the head even a restriction with a stock ish cam?

I don't have any proof other than being told that the AU heads flow better than the earlier heads