While I'm driving with the Air conditioning system off the vents blow heated air. Why?

 

Late model D1 and all the D2 always circulate coolant through the heater core. If the doors don't close all the way in the blower box, a lot of heat will leak through. Something might need adjusted or repaired, but try turning the temp all the way down to LO on both controls before turning off the climate control and see if that helps.

 

We all have this issue! Just crack the window and smile its a disco thing!

 

I have also found that if you run the a/c first for a minute the hot air will be less noticiable.

 

Same issue...not like it is BLOWING hot air, but it comes through the vents.
I live with it and understand how the heater core continues to circulate, but I wonder if the Discoverys right out of the factory did this?
Is there is something in the system... a "flap" that does not close 100% in the dash after the LR ages.
If I wanted this issue resolved, could it?

 

Yes, they all do it. Way back when people started complaining about it Rover switched a number of parts including the control panel, didn't fix a thing.

 

Disco Mike, This problem sounds like something that will be an issue for me in about 4 months. Can I put a shut off valve in the heater core supply line and close off or regulate the hot water supply when not needed? Would this cause any big problems with the cooling system flow?
Thanks for you thoughts.
P.S. Working through your high mileage maintenance list.

 

Heater cores are frquently bypassed in very warm areas. Make sure you arrange valve to bridge the unit, rather than just dead ending.

 

Thanks!!