This is not a big issue and it's something I can easily live with but I figured i'd throw it out there in case there is an easy fix.

My heater/AC is always on. Basically when you turn the vent system off it will continue to blow air It blows whatever setting the system was on when it was turned off. It only seems to blow heavy when on the hwy, when driving around town it blows but very little.

Any ideas.

 

Sounds like your driver transistor is shorted closed.
Probably an open collector PNP type.

 

My 02 has the same problem but I never bother to look into it.I figure if a disco is not overheating and its liners are staying put....its running perfect!

 

So, are you saying the fans never turn off or do you still get air flow when off that might vary based on your vehicles speed?

 

Don't know about op but when My fans are off I still get air flow with vehicle speed.

 

X2, volume dependent on speed, and temp dependent on outdoor temp.

 

If you pull fuse 7 under dash that should stop main HVAC fan. Then you can decide if you have a fried relay or power transistor module.

 

D Mike, it blows depending on the speed of my truck. On hwy it's blowing pretty strong when vent is off, when in city it's minimal. Is there a way to set the vent so it's just blowing air from outside instead of always setting temp involving heat and AC? I could live with that.