Ok, my 2000 disco 2 just had a serpentine belt and its water pump replaced. Because the belt shredded apparently because of the water pump. So I get it back and I am drving do the road with my air conditioner on sixty and it starts to overf heat. No red light because I shut it off. So I stopped waited ten min and I had to get to work but as I started to drive with the temp just above half the car cooled itself back to half. Mind u I had turned the air off. I get off work and drive it twenty miles home with no air and it ran fine with a normal temp. It did this same thing a week ago with the air seeming to over heat the engine. Now to my last concern my red transmission temp light is coming on. It has done this on and off for about two years. It started one night after driving through a river. And so far it hasn't done anything so from all I have read I feel like it is a short. But I have no clue. So I guess my question is will my air conditioner overheat my engine if certain things occur or do I have a bigger problem. The heads were replaced twenty five thousand miles ago. Thanks for the help. The car has 170000 miles on it. But the engine was replaced with a used one at 130000 miles. Please help guys I just paid 800 to have the belt and the pump replaced. Please help.

 

Are your electric fans working when the a/c is on?
Did they also replace the fan clutch when they did the water pump?

As for the trans temp light, you need a new trans temp sending unit.

 

No they did not replace the fan clutch. What I am wondering is can I drive this thing without the air and not overheat it

 

Just checked the fan is running driving to work right now. No temp problem yet. But the red tyranny temp light just came on.

 

Tranny light is now off.

 

Ouch!!! Are you mechanically inclined? You could have saved about $600 doing that yourself. You could drive it and keep looking at the gauge but something is wrong. I agree with Spike on the fan clutch. Unless you know they replaced that, I'd look into that first.

Eric

 

I mean I have never really worked on cars but I am capable I would think just need some know how

 

They did not replace the fan clutch. I do know that but the fan is running.

 

The clutch fan will "run" as long as the engine is running, it is connected directly to the waterpump BUT what it does is freewheel, meaning is just spins because of the friction between the fan and the waterpump shaft.
But when the engine gets hot the fan clutch locks up and then the fan spins at the same speed as the engine which is faster than when it is freewheeling and then it cools the engine off.
If all it does is freewheel then it wont move enough air to cool the engine.

If there is not enough air moving though the radiator then the fan clutch will not get hot enough to lock up.
So start by washing both sides of your radiator with the garden hose to make sure there is no pollen, dirt, leaves, etc. clogging the fins and restricting air flow.

 

So why is my car only overheating with the air conditioner running.