HVAC heat blows warm/hot on drivers side, cool/cold passenger side (warranty issue)

[Eggman]

I came across some interesting information regarding this corrosion, though from a different angle. Have a look at the attached documents from A.O. Smith on aluminum hydroxide as it pertains to water heaters. The substance is described as similar to what Daox found in his heater core (or matrix) and is caused by water with high PH:

In a few isolated parts of the United States where the water supply has a relatively high pH (8+), water conditions will react with the aluminum anode to form excessive amounts of aluminum hydroxide on the anode and in the bottom of the tank. Aluminum hydroxide looks like “jelly beads” or a green, blue or gray gel like substance in the heater drain or at faucet aerators.

A.O. Smith lists a product to treat this that they call Un-Lime. In their Bulletin 14 (attached) they recommend using Un-Lime heated to remove the aluminum hydroxide.

In another document (also attached) A.O. Smith lists a different procedure for using Un-Lime and in it they stress to not allow the solution to come in contact with the sacrificial aluminum anode rod:

Because deliming compounds dissolve sacrificial-type anodes used in most water heaters, it is important that solution be kept below the level of the anode rod, fig 3. Magnesium and aluminum are typical sacrifial anode materials.

DANGER
KEEP ALL DELIMERS AWAY FROM SACRIFICAL-TYPE ANODE RODS TO PREVENT THE FORMATION OF FLAMMABLE AND EXPLOSIVE GAS.

If most of the Mirage cooling system is composed of aluminum - engine block, heater core, radiator, water pump - it sounds like using an acidic solution could/would be harmful.

In another section of the document A.O. Smith has the following:

TERMS	DESCRIPTION	REMOVED BY	PROBLEM CAN BE REDUCED OR ELIMINATED BY
Water Scale - Lime (Hard Water)	Calcium and Magnesium Carbonate	Deliming with Un-Lime Professional Delimer.	Water softening or feeding glassy phosphates
Water Scale - Other	Silicates, Sulfates, Aluminates, etc.	Manually scraping	Cannot be eliminated but effect can be greatly reduced by periodic deliming with UN-LIME.
Silt	Fine particles of soil or sand suspended in or deposited by water.	Flushing	Clarifier Filter

This suggests that when it comes to what Daox found fouling his heater core, there may be no solvent that can flush it out. Preventing PH levels from getting out of hand may be the best approach to dealing with this.