Had a smell of coolant in the cabin and my local Mits dealer believes this is the reason.
Failing that it would be a cracked heater core.

I've heard that this is a common issue with the heaters in these cars. The KH has nearly 200K's on it now, so if it was going to happen then I guess it's due.
There is a risk of sudden leakage into the control unit, under the dash, so I need to get this fixed.

The plan is to replace the heater O rings, which apparently is possible without removing too much of the dash. Basically just the glove box and some air-con components. (will need re-gassing). If that doesn't work then looking at the bigger job of replacing the heater core which involves pulling out all the dash.

Anyone had this done? Any issues?
[edit], oops, sry, posted in wrong forum. This is on my 2WD KH, not my AWD.

I do this on a regular basis, cost is $350 if you only need seals, $475 if you need core and pipes as well. this is provided you do not have aftermarket parts fitted to the dash that will take extra time to remove

I would recommend against touching the air con, great risk of getting moisture into the system as well as dirt plus the added cost. Dash is not a big deal to remove at all.

If you want to do DIY, I have some time ago made up a step through which a search should locate for you on how to get the dash out

...
I would recommend against touching the air con, great risk of getting moisture into the system as well as dirt plus the added cost. Dash is not a big deal to remove at all...
Hi MadMagna, do u mean you're recommending removing the whole dash to gain access rather than just the glove box and whatever air-con components are in the way?

Yes I certainly am suggesting this, this way is the correct way, does not risk your aircon (plus the cost of the aircon degas and regas) and allows good access to do the heater properly

Removing the dash is not such a big deal either lol

Update: The cars in the workshop tomorrow (with our own Madmagna) to have this sorted out.
Fingers crossed its just the seals...

I forgot to update you, all: Job done and all is well. :)
MadMagna said something about the new rings probably lasting longer than the originals.