I have a 1996 Disco sd with 125000 on it. automatic. as the temperature in Tulsa drops so does the operating temperature in my rover. it is practically nothing on a cold day like today (24 degrees). it will warm up at idle and slower speeds but if i am moving above 45 mph it goes lower and lower. I'm talking like it's all the way at the bottom. and my heater works. blows hot air. weird. it worries me a little!

Also, my heater controls are a pain in the rear. if i put in just the right spot, between 2 and 3 somewhere, it will blow but if not it just barely blows. pretty annoying. has anyone else had this problem or know how to fix it?

 

Check thermostat. If one made for land rovers can not be found, use one from a chevy 4..3 v6. Fits in perfectly. I have same problme with my controls, i have to find the sweet spot to get it to blow. I live in tulsa as well by the way.

 

Yup, you need a new thermostat, AutoZone has them, so does your dealer.
$15 and 15 min. Make sure that you get a new gasket also.

 

Thanks for the input. That's what i figured. I'll replace that tomorrow.

 

Got any steps for that thermostat replacement?? Do you have to drain the coolant as well?

 

Madbilly, good to know there are other rover lovers in tulsa! As soon as the weather changes i am going to put that thermostat in, but knowing this wonderful state, it'll be 80 degrees for a week and i won't be able to tell if it changed anything!

 

After replacing the t/stat, make sure to bleed all the air from the coolant system, while the engine is stone cold, then you won't have any over heat issues.
As for your fan switch, common and expensive cause you can't just replace the switch, got to replace the whole thing.

 

With the engine cold remove the upper radiator hose, remove the "goose neck" from the top of the engine, mark the side of the t-stat that is facing out towards you with a paint pen.
Take a straight razor blade and clean the mating surface on the engine and goose neck.
Rough both surfaces up with a fine grit sand paper if you need to.
Make sure that the new t-stat is installed the correct way, make sure that you use a new gasket too.
Tighten the two bolts that hold the goose neck on evenly and CAREFULLY, if you get one side to tight you can break off one of the ears.
Replace upper radiator hose, bleed cooling system and top off with coolant.

 

Driving with a bad thermostat will greatly reduce your MPG and carbon up the cylinders.