Heater matrix crud dislodging fluid

Does anybody know of a descent fluid that I can put into a heater matrix to loosen any crud that might be in there?
This is a non Fronty related question as it's my diesel Sedona that is like an ice-berg when I go out in it and typically, didn't find out till I needed the heat.
Took it for a drive out earlier so I could see what was going on regarding heat in the pipes, top rad pipe hot, one of the pipes into the heater is hot so I guess that's the feed and the other which I guess is the return is cold. Wouldn't thought the heater matrix would have dispersed, absorbed the heat in the pipes to that extent, so I'm guessing it's either blocked or there is a air lock in it.
I'm thinking of taking it pipes off and trying to fill the matrix with some sort of cleaning fluid then giving a good it a proper job flushing out to see if that sorts the problem before going to the pain of removing all the dash to get at the heater matrix out.
Short term I'll be using the Fronty because that is lovely and warm.

Forte bio-degreaser for cooling systems is probably the best stuff you can get.....
Read the instructions on the bottle very carefully......It is good stuff.... :axe:

have you just tried a good flush with water ?

Cheers guys for replys - Fogman, no I haven't tried just flushing as I want to give it a clean out with something whilst I'm in amongst it.
On these MPVs there are branch off pipes that feed the rear cabin heater so I want give the whole system a good clean.

Remember to add some antifreeze as temperatures are set to drop below zero this week :wink:

I chucked some in to be safe

Phew

Update on this post - Sedona is a warm as toast

Noticed slight coolant leak on one of the rear heater pipes that I bodged up as a cheap fix when the original metal pipes corroded. The coolant capacity on my Sedona is 9.4 litres and it took 4 litres topping it up after I noticed the leak.
Certainly proved a point to me that if coolant is low, it will effect the heat output required.
I've got a Kia produced workshop manual that the main Kia dealerships use for repair instructions.
The procedure on my model of Sedona for refilling the coolant system is to remove the radiator cap and run the motor until the top hose is hot (I guess this opens the thermostat), then fill with 45% mixture via the radiator cap. I guess the idea is that the coolant runs down to the radiator and back up through the engine to allow the trapped air to be pushed back up to the filler neck. I then have to top the expansion tank up.
Although my Fronty differs in the fact that the expansion tank is the filling point, I wonder if this theory will work on the Fronty as well. As was pointed out to me, only worry would be cold coolant possibly passing through a hot cylinder head.
The other test on the coolant system is to pressure test up to 15PSI and see if the system holds the pressure. Again, I wonder if that could be crossed referenced with the Fronty.

A series is easy enough to refill and bleed.

Engine off, fill through the coolant bottle until at the cold mark, leave cap off and start engine. Keep topping up until thermostat opens and the level stops dropping. take for a drive and keep an eye on the level. Top up if necessary.

That method has never failed to date.

B series are a little more complicated though.