Heating problem

Hi, I have a Mazda 5 2007 with 145000 Km.
I have a problem with the heating, when driving the car the air that comes out of the vents is warm.
But when the car is on idle, the air that comes out of the vents is cold.
What could be the problem?
 
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Northeast
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2020 CX-5 Tour
My choice would always be to try diagnosing first, before throwing any parts, but this is your vehicle and your choice.

If you decide to try diagnosing, the first thing to do is check the coolant level at both the cap and tank. If the level is ok, then it's really helpful to be able to know the actual coolant temps as the cabin heat changes. OBD ECT temp is the best way to do that, but you can use an IR gun to check the hose temps, if you don't have a live data tool.
 
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Coolant level is fine, as for the IR gun, I don’t have one.
Could the problem come from the heater core or thermostat.
When driving the heat is ok.
 
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:
Northeast
:
2020 CX-5 Tour
.... Could the problem come from the heater core or thermostat. ...
There are quite a few players involved in getting the heat to the cabin, and trying to replace all of the possible suspects gets expensive fast. It could be something as simple as a faulty blend door/actuator, or a number of other things, but it's all guesswork without diagnosis and testing.

I'd start the process by finding out what the actual coolant temps are, but others might try some other testing instead, and another group would just fire the parts cannon. This is your vehicle, so how to proceed is up to you.
 
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There are quite a few players involved in getting the heat to the cabin, and trying to replace all of the possible suspects gets expensive fast. It could be something as simple as a faulty blend door/actuator, or a number of other things, but it's all guesswork without diagnosis and testing.

I'd start the process by finding out what the actual coolant temps are, but others might try some other testing instead, and another group would just fire the parts cannon. This is your vehicle, so how to proceed is up to you.
Thanks for info
 
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2008 Mazda5 GT
Suspect you have a leak in the coolant system that is letting air in. Do you hear sloshing in/around the glove box area?

first thing to do is to burp/bleed the coolant system (easy to do, check youtube). If this being the heat back to norm op temp, then there a leak somewhere. Next run a bottle of coolant dye to find out where the leak is. Given the cars age (in years), it is boarding where a lot of rubber/seals are getting old
 
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Suspect you have a leak in the coolant system that is letting air in. Do you hear sloshing in/around the glove box area?

first thing to do is to burp/bleed the coolant system (easy to do, check youtube). If this being the heat back to norm op temp, then there a leak somewhere. Next run a bottle of coolant dye to find out where the leak is. Given the cars age (in years), it is boarding where a lot of rubber/seals are getting old
Thanks for the info, I’ll try that.
 
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