Car blowing air while set to heat ?

I’ve noticed my coolant keeps disappearing out of the tank but I see no visible leaks also it just started getting cold in my city so it’s time for heat but my car blows out air instead of heat until I start driving then it kind of switches from heat and cold back and forth taking it to the shop this week but anyone knows what is causing this?? It’s an 09 mailbu

18 Answers

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  • zipper
    Lv 6
    1 month ago

    You have a leak some were, take it to a mechanic and have it checked out. The hot and cold is there is air in the system and the air does not give off much heat. Check the oil for water, and the exhaust if it is leaking under pressure it will be blowing out the tail pipe when running in a white cloud.

  • Anonymous
    1 month ago

    Worst case scenario is a cracked head blowing coolant out the exhaust manifold. That's usually where the mystery coolant is disappearing to if you have no leaks and are constantly topping the coolant level.

    The plastic intake plenum may be cracked by the EGR valve port, this is common on the GM V6 engine. Pull the spark plug closest to the EGR valve and check it for coolant residue on the spark plug electrode.

  • Anonymous
    1 month ago

    THE "COOLENT" leak could be condensation from the air conditioning unit.

    And as for your car not being warm if your only traveling short distances it does not have enough time for the engine to heat up the water in the engine cooling system to proved heat!

  • 1 month ago

    You either have a coolant leak or bad head gaskets. Your symptoms with the heat is a dead give away you have an air pocket in the heater core.

    Source(s): Mitsubishi Master Tech
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  • Ray
    Lv 7
    1 month ago

    You could be burning coolant and be low on coolant. I would make sure that the intake or head gaskets are not leaking. GM is prone to leaking intakes.

    • M.
      Lv 7
      1 month agoReport

      Ethylene glycol DOES burn. 232° F is its "flash point".

      The water part of "coolant" does not burn. It turns to steam from the heat of combustion and may escape the exhaust system unnoticed, unless the volume of the leak is great enough. Then it's a white cloud.

  • 1 month ago

    The air blown through the cabin is heated by coolant circulating through a small radiator, know as a heater core, that is usually located near the top of the engine. If your coolant/antifreeze is low, it may not circulate through the heater coil and the air isn't heated. The reason you get heat when the engine is hot is that the coolant expands as it heats.

    You need to have someone more qualified find out what is happening to the coolant and fix whatever that is.

  • Anonymous
    1 month ago

    You first asked about low coolant/overheating 2 months ago . . . . what did you do at that time that apparently didn't work. Tell us what's been done so far and we can eliminate some of our guesses.

    • M.
      Lv 7
      1 month agoReport

      Two months! Ouch!!
      This is bad.

      Could be an initial intake manifold gasket leak which happened on those V6 Chevrolet engines.
      Then long-term overheating warps the aluminum cylinder head which causes a second coolant leak.

      Then you're chasing 2 different causes of the same symptom.

  • 1 month ago

    Low coolant is causing your heater to blow cold air.

    As you say the car keeps losing coolant you need to trace the leak and fix it.

  • 1 month ago

    maybe you should have a mechanic check it out

  • arther
    Lv 4
    1 month ago

    low coolant level is the cause of the heater not blowing hot air if your topping it up regularly, GM alloytec V6=POS

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