(Not sure if this belongs here or in general tech. Let me know if I should move.)

My 2003 Disco seems to have floor heat always on. The only exception is when the A/C is running. Have taken it to dealer multiple times and their opinion is that it's heat coming off the transfer case. That's not it. My RR classic had a lot of transfer case heat - I get that. This is different. I have heat coming out of the floor vents all the time the A/C is not running.

Heat and a/c work fine otherwise. I'm guessing water is flowing through the heater core all the time. Is this possibly a stuck heater core valve?

 

A DII does not have a heater control valve, even when off heat still goes threw the heater core, even in AC heat still goes threw the heater core.
the only way to stop it other than installing a control valve is to turn the temperature setting down to a colder setting.

 

Got it. I still get heat all the time. Thermo is almost always on low setting unless it's very cold out. For example, when it's 70 degrees out and I have everything set to Lo, the only way to not get heat is to turn on the a/c.

 

It's tech question about a Disco II so your in the right place

 

or set it on cool and hit the econo button the will kill the ac compressor.
but without a heater control valve you can not stop it,
if it bothers you that much you could install a universal control valve off ebay for like $30.

 

The issue is that the Econo button = heat in my truck. There doesn't appear to be any way for me to get any venting without the air being heated, regardless of the outside temp or where my thermo is set.

I'll take a look at the universal control valve. Thanks for the tip.

 

you need something like this:
HVAC Heater Control Valve Shut Off Valve 4 Seasons 84707 | eBay