Well, in any vehicle, if the heater core hoses have been removed on the engine side of the firewall and bypassed, that takes the coolant out of the picture. It is possible if heater is still connected that you could have a jammed flap, etc. While not very safe, you may have to have an assistant drive while you feel around under the dash for the source of the air flow, either from heater system or various chassis holes already mentioned.

Rover distributed models to North American Sprecification (NAS) and rest of world, with a number of variations. The 3.9 is covered in the RAVE, you may have to look in other portions of the RAVE (like Defenders) for the heater controls.

If you plan to block off the heater coolant pipes, do so as a loop, don't just dead end each of them.

 

Thanks for all the advice, I think I will post a few picks of my truck for you all to see. Looks like I have a few things to check at the weekend!!!! Unfortunatley it feels like I am correcting the PO's half hearted attempt to restore a cracking example of a Disco. Nevermind, brakes and track rod ends getting done on Monday so its slowly coming together.

Thanks again.

 

You have the "hard dash", it is not like a Defender it is the Range Rover Classic dash.
They didnt go with the "soft dash" until '94.
That dash has rotary ***** for the HVAC unit.
I love the hard dash, looks like a tractor instrument cluster only with a mile odometer instead of a hour meter.

 

Thats clear, never thought of it as a tractor till you made the analagy, being a country boy I am pretty happy with that. I have also noticed that my aircon appears to be a completly seperate system to the main blower, and I'm not sure its been put back together properly......gotta love it!!!

 

FIXED!!!! So, I took out the centre console and most of the dash so I could access the area the heat was coming from. Turns out, in the right hand side of the blower (mine is a right hand drive) there is a plastic vent with two rubber flaps. This leads up to a vent just underneath the windshield in the center underneath the bonnet. One of the rubber flaps had almost completly torn off so, in short, when I accelerated, all the hot air rushing over the engine was coming through that vent, into the drivers foot well. So i have re-sealed it, and now its so much more comfortable. Thanks for all your advice guys. I have a few images to upload of the offending item for reference.

Cheers

 

Glad to hear you got the "old beast" doing better. They were basically a farm vehicle dressed up, what we refer to as a 'pig wearing a dress'. To bad LR went to fancier and fancier dresses instead of maintaining and upgrading the beastly aspects of the machine.