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  1. #1
    Administrator Daox's Avatar
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    HVAC heat blows warm/hot on drivers side, cool/cold passenger side (warranty issue)

    UPDATE: Issue found

    See heater core dissection:
    https://mirageforum.com/forum/showth...ll=1#post77015



    =========================================



    For those of you following my garage thread for Swarthy, you know that I have a bit of a HVAC heat issue. I get warm / hot air out of the driver's side vents, but cool or cold air out of the passenger side vents.

    I noticed the issue on the 2 hour drive home from getting the car. The car simply did not get overly warm in the cabin. On the test drive everything seemed okay. Spork also confirmed this as she went with me to get the car.

    On this morning's trip in to work, I did a bit more testing of this. I found out that it simply does not blow hot air with the fan blasting. It does blow warm, but not hot. This is despite the engine coolant being fully up to temperature (180F+). The driver's side is a lot warmer than the passenger side, but still not as hot as it should be IMO. It is noticeably cooler than any other car I've owned.

    I also tested the temperature out of not only the normal vents, but the defroster vent and also the floor / feet vents. The same thing happens. The driver's side blows much warmer air than the passenger side.

    I had a suggestion from Eggman to check to see if the cabin air filter was at fault. I did this and noticed it had probably never been changed. I cleaned it up as best I could and reinstalled it into the car. It definitely was dirty and needs replacing, but it is not fully clogged at all. Unfortunately, cleaning the filter out did nothing to fix the issue.





    At this point, I am thinking I have a busted flapper door, a bad stepper motor that isn't actuating a flapper door properly, or something is jammed in there stopping a flapper door from shutting correctly. It seems like some or a lot of cold air is coming in and mixing with the heated air from the heater core. I'm not sure why most of the cold air is going to the passenger side, but that seems to be the case. I'll be looking through the service manual to see what needs to be taken apart to start getting to the bottom of this. Any info, tips, or ideas are quite welcome!
    Custom Mirage products: Cruise control kit, Glove box light, MAF sensor housing, Rear sway bar, Upper grill block

    Current project: DIY Nitrous oxide setup for ~$100

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 45.4 mpg (US) ... 19.3 km/L ... 5.2 L/100 km ... 54.6 mpg (Imp)


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    Administrator Daox's Avatar
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    Just talked with my boss at work who does a lot of car work. He said someone he knows with a 2013 Jeep with ~100k miles (somewhat similar to my 2014 with 77k) had the same issue. It ended up being the heater core being plugged. They flushed it and everything went back to normal.

    That also would make sense in this instance. If the inlet is on the driver's side, it gets all the heat. By the time the coolant gets to the passenger side its already cooled off. One more possibility to check!

    Ironically, it wouldn't be the first time I flushed a heater core over Christmas vacation. Two years ago I did the same thing to my Chevy Metro.



    Custom Mirage products: Cruise control kit, Glove box light, MAF sensor housing, Rear sway bar, Upper grill block

    Current project: DIY Nitrous oxide setup for ~$100

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 45.4 mpg (US) ... 19.3 km/L ... 5.2 L/100 km ... 54.6 mpg (Imp)


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    Moderator Eggman's Avatar
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    Quote Originally Posted by Daox View Post
    If you do flush your heater core, perhaps you could route the discharge into a bucket to see what comes out.


    Quote Originally Posted by spork View Post
    It was blowing warm air during the test drive!
    Also, if it blew heat on the test drive as Spork says, why would that change now? Do you think the antifreeze mix if somehow off? Were both driver and passenger sides checked?
    Last edited by Eggman; 12-15-2017 at 07:56 AM.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.8 mpg (US) ... 21.2 km/L ... 4.7 L/100 km ... 59.8 mpg (Imp)


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    Administrator Daox's Avatar
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    Quote Originally Posted by Eggman View Post
    If you do flush your heater core, perhaps you could route the discharge into a bucket to see what comes out.
    That is the plan. I already picked up the stuff necessary for the flush. I should be able to get to it this weekend.


    Also, if it blew heat on the test drive as Spork says, why would that change now? Do you think the antifreeze mix if somehow off? Were both driver and passenger sides checked?
    It does blow warmish on the passenger side as long as you don't blast the heat. More indications that it is a plugged core IMO.

    It'll be interesting to drain and flush the core. Perhaps the previous owner had the coolant replaced with the incorrect type? I'm not sure what I'll find. The overflow tank has blue coolant in it, but that doesn't mean there isn't something else in the block. I'll be draining the whole thing and probably flushing the radiator, block, and heater core depending on what I all find.
    Custom Mirage products: Cruise control kit, Glove box light, MAF sensor housing, Rear sway bar, Upper grill block

    Current project: DIY Nitrous oxide setup for ~$100

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 45.4 mpg (US) ... 19.3 km/L ... 5.2 L/100 km ... 54.6 mpg (Imp)


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    Administrator Daox's Avatar
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    I also went ahead and picked up some CLR.

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    Before going ahead and dumping it into my heater core, I figured I would give it a test run. I recently cut up some 6061 aluminum sheet. This is probably the most common aluminum alloy and likely what the heater core is made out of. So, I grabbed some scrap strips of aluminum from the project that I was working on, and setup a test.

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    I poured some CLR into the glass bottle this morning before work and stuck the aluminum strips in it. This is full strength CLR, not watered down at all.

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    Here is how the aluminum looked when I first put it into the CLR.

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    I had to leave for work about 15 minutes later. But, this is how it looked then.

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    From those pictures, I can't see any etching like the CLR FAQ page claims. So, I am going to assume that at the very least, using it for 15 minutes is perfectly safe. I plan to do this test again, but with something rusty to see how fast it eats away at the rust, and if 15 minutes will dissolve it to the point that it will wash off easily with running water (not scrubbing) to simulate the water flushing it out.
    Custom Mirage products: Cruise control kit, Glove box light, MAF sensor housing, Rear sway bar, Upper grill block

    Current project: DIY Nitrous oxide setup for ~$100

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 45.4 mpg (US) ... 19.3 km/L ... 5.2 L/100 km ... 54.6 mpg (Imp)


  6. The Following 2 Users Say Thank You to Daox For This Useful Post:

    Top_Fuel (12-15-2017),Wayne (12-29-2017)

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    Senior Member Top_Fuel's Avatar
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    Quote Originally Posted by Daox View Post
    ...I also went ahead and picked up some CLR...
    ...I am going to assume that at the very least, using it for 15 minutes is perfectly safe.
    Awesome experiment! Thanks for taking the time to do it. I don't think I'd have any reservations about using it for a limited time period like that...especially if you flush it all out completely. My experience is that products like "Prestone Super-Flush" are just way too mild for serious corrosion problems.

    There are some good Youtube videos showing how guys did this. HERE is one where it doesn't look like the guy's heater core was that bad...but just flushing with water made a significant improvement.


    Quote Originally Posted by Wallythacker View Post
    ...What if your car previously had a cooling leak, real or imagined, and the prior owner decided on a DIY fix with whatever goop he could pour into the rad to seal the leak?
    Hopefully if the heater core is full of something like "Bar's Leak" it will all flush out! Wouldn't be the first time that's happened. Have you ever looked inside a can of that stuff?!? Lol...
    Last edited by Top_Fuel; 12-15-2017 at 02:09 PM.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 51.5 mpg (US) ... 21.9 km/L ... 4.6 L/100 km ... 61.8 mpg (Imp)


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    Quote Originally Posted by Top_Fuel View Post
    Awesome experiment! Thanks for taking the time to do it. I don't think I'd have any reservations about using it for a limited time period like that...especially if you flush it all out completely. My experience is that products like "Prestone Super-Flush" are just way too mild for serious corrosion problems.
    I thought it was an interesting idea just to see how badly it actually will attack the aluminum. Chances are, overnight will barely do anything to it. It will probably dull a polished surface though, and that is why they have the warning in their FAQ.

    There are some good Youtube videos showing how guys did this. HERE is one where it doesn't look like the guy's heater core was that bad...but just flushing with water made a significant improvement.
    Yeah, thats what I've done in the past. It has worked quite well.
    Custom Mirage products: Cruise control kit, Glove box light, MAF sensor housing, Rear sway bar, Upper grill block

    Current project: DIY Nitrous oxide setup for ~$100

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 45.4 mpg (US) ... 19.3 km/L ... 5.2 L/100 km ... 54.6 mpg (Imp)


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    Senior Member MightyMirageMpg's Avatar
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    Have you Check to see the heater core is actually getting hot? There's a vacuum valve inside the car that i don't think is monitored.

    The flapper actuators all have positional feedback, so 9/10 you Would Have a code unless the doors itself is messed up

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    Daox (12-13-2017)

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    Senior Member Top_Fuel's Avatar
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    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.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 51.5 mpg (US) ... 21.9 km/L ... 4.6 L/100 km ... 61.8 mpg (Imp)


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  14. #10
    Administrator Daox's Avatar
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    Quote Originally Posted by Top_Fuel View Post
    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.
    Custom Mirage products: Cruise control kit, Glove box light, MAF sensor housing, Rear sway bar, Upper grill block

    Current project: DIY Nitrous oxide setup for ~$100

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 45.4 mpg (US) ... 19.3 km/L ... 5.2 L/100 km ... 54.6 mpg (Imp)


  15. The Following 2 Users Say Thank You to Daox For This Useful Post:

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