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

[Daox]

Just a random tip regarding heater core flushing...

If you can isolate the heater core, drain it and fill it up with a product like CLR. Let it sit overnight...and then flush it. A local shop owner told me he fixes most clogged heater cores with this trick.

For due diligence I checked CLR's website. Their FAQs section specifically says not to use it on aluminum surfaces. I am a bit hesitant to use it after reading their site. I may still use it as I'm sure it will help clean the heater core better. If you google CLR heater core, tons of stuff comes up.

http://www.jelmar.com/CLRbasic.htm

What will CLR do to brass, copper or aluminum?

CLR can not only remove the finish off of brass, aluminum and copper, but can also pit certain grades of brass, copper and aluminum.


What surfaces should I not use CLR on?

DO not use CLR on any natural stone or marble (including cultured marble), terrazzo, colored grout (any other color than white), any painted, coated, sealed or metallic glazed surfaces, plastics, laminates, Formica, Corian, aluminum, galvanized metals, nickel, oil rubbed bronze, brass, copper, steam irons, leaded crystal, refinished tubs or any damaged or cracked surface. CLR may etch older sinks, tubs and tiles. CLR is corrosive. Avoid contact with wood, clothing, wallpaper and carpeting. Some laminated surfaces (counter tops) are coated with a synthetic surface which may be affected by rust removers; clean spills immediately. Always spot test first on an inconspicuous area.