Hello

I have a 2007 Tucson, when you turn on the heater it only blows hot air when your foot is on the gas pedal, the rest of the time it blows cold air. This just started recently, like last Saturday. The temperature dropped to -50 degrees overnight, with a daytime high of -37. Just want to know what it might be and if it would be covered by Warranty. My husband is handy so he may be able to fix. Thanks

 

It's should be still under the 5 year / 60,000 mile bumper to bumper warranty. Take it back to the dealer to have it looked at.

 

I turned on my heater today on way home and it was blowing cold air? I cranked up the heater control up to 89 for nearly 10 minutes and it was blowing cold air? When I got home I shut off the car, and came out and started the car up. The heater was blowing strong then. Has this happened to any of you before? I was wondering why wouldnt it not work the first time on the way home? I appreciate the input.

 

there could be a few reasons as to why these circumstances occur. based upon the limited information on the options, i will list the most common causes first, then through the less likely but still plausable scenarios.

a low coolant level will exhibit the first stated symptoms of no heat/low heat at idle and increased heat at cruise due to an air pocket. if the cooling system has recently been worked on, make sure it has been bled properly. if not, check the coolant level and pressure test for leaks if it is low. do not overlook the radiator cap as a possible source of a leak. if the shop doesn't have the proper adapter to check the cap, then find one that does. (and if they say they do, then show them how it fits....you're allowed to, ok??)

the second set of symptoms could be related to the above listed symptoms, and could have built up heat through the thermal transfer from the hot engine to the cooling system (it's supposed to do this). this would only be temporary, though, as once the coolant gets circulated through the radiator the temperature of the coolant will drop significantly to be able to 'pick up' additional heat from the engine.

another likely cause is a malfunctioning thermostat not allowing the coolant to sit in the passages long enough to develop a sufficient transfer of heat. this can be verified with an infra red temp scanner to check the temp of the hoses from a 'cold start' (stat closed) to a 'full op temp', when the stat opens. this may also be accopmanied by a lower than normal guage reading from the dash.

from there, if these areas all check out, then we are looking at a heater core restriction, or an airbox/blend door (control/setting) issue. again, with the infra red temp scanner you can compare the temps of the inlet and outlet hoses to the heater core. there should be sufficient difference, and, as with the stat, can be most accurately checked from cold to normal op temps to verify if there is a restriction. if the outlet hose does not warm up significantly after the inlet gets hot, and no heat through the vents, then i would say this points to a heater core issue. if the heater core hose temps are both hot, then that indicates coolant flow, but if there is no heated air through the vents that could point to a blend door/control fault. put the settings on defrost (this is the 'default' setting that should still work when all else is going haywire). if there is heat here, then you are looking at a blend door/mix control issue.

blend door/control malfunctions can sometimes be caused by the ambient temp sensor failure or heater control unit (hvac or head unit). they can also be caused by malfunctioning motors, vacuum actuated devices, of aftermarket items installed improperly. (hint, these sorts of repairs can become pricey...)

i hope this helps.


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