[pizza71]

After driving for 30-40 minutes the air flow from vents goes from high velocity then down to a trickle. I can hear the fan motor running but very little air flow coming out of vents. The air flow is always fine when I first start the car, but diminishes after driving for awhile. Mechanic can not find anything wrong since he can never duplicate the problem in the shop. Doing a bunch of google research it sounds like a bad evaporator sensor. Has anyone had to replace this, and is it a DIY job? Thanks!

 

[Zechariah936]

Are you using it on auto or manual airflow settings? Is it on cooling or heating? Does the HVAC do the job of heating and cooling in the 40mins?

 

[SlyCoopers]

^ thats a really good question if auto or not. I haven't touched the ac system of the mazda but on other cars historically the fan is separate from the ac component. You could have a broken condenser or cut ac line etc and all the sensors would do is make sure the compressor doesnt turn on so you wouldn't get cold air but air would still blow.

The blower fan is just like a fan that only changes speed. My experience with nissans on this issue had some sort of electrical component resistor type part (cant remember for the life of me what its called) that would control fan power and if there was an issue with blower not working it was either this part or the blower itself.

Cx3 wise there's another phenomenon ive had happen occasionally. I would leave the fan control on the lowest speed or one notch above lowest (not auto) and it would randomly decide to just go full speed. Idk if this is slippage related to the hvac controls on the dash but anytime this happened id move speed up and down a notch and it would work as it should have. Im gonna swap out the dash controls if this happens more frequently in the future but at this rate it's like once maybe every 3or 4months so its been weird.

Also check your cabin air filter behind the glovebox. I discovered the joys of mice using engine cover insulation and stored it above the filter recently which was unpleasant and blocked most air flow.


Couple of things to check out and report back including the above post:

Does fan speed issue change if you turn air recirculation on and off?
Does changing fan speed up and down back to what it was when the speed drops fix the problem?
Is ac on while this happens?
Is heat on while this happens?


Also for the sake of ruling out the obvious, are you driving when fan is blowing more then stopping when its blowing less?

 

[DazMan]

How bizare ths is, as this exact same issue happened to me yesterday. Air con worked perfectly on first initial driving, the as describded, it just gave up as such, even not blowing cold air as well, No chnage in fan speed would work either, even tried on Auto to with no luck.
Parked car for about 20 mins, hopped back in and all worked perfectly, fan blowing cold air, fan worked on all speeds, yay happy days....... Well for about 20 mins then back to same issues not blowing cold, fan not working.
Checked Cabin filter, all clean, where does these cars actually pull the outside air from, but today.... Car is working as normal....
Frustrating .
Hoping that someone can help or suggest what is happening.

 

[Laran70]

I have the same problem. Try look under the hood next time it happens. You probably will see the AC line covered in ice due to the temperature of the coolant is below zero degrees Celsius.
My theory is that the condensation water freeze to ice preventing the flow of air. Once the ice has melted the air can flow freely again.

 

[DazMan]

I have the same problem. Try look under the hood next time it happens. You probably will see the AC line covered in ice due to the temperature of the coolant is below zero degrees Celsius.
My theory is that the condensation water freeze to ice preventing the flow of air. Once the ice has melted the air can flow freely again.

Had my car looked at and it seems the Evaporator Temperature Sensor needs replacing........ Parts are cheap........ Apparently the whole dash has to come out to change this little thing that pushes into the Evaporator, that then tells the Compressor to turn off and on...... Hoping there is a work around this as I do not want to remove the whole dash out of me car, plus quoted some huge as "F" price to do it as well

 

[Zechariah936]

Had my car looked at and it seems the Evaporator Temperature Sensor needs replacing........ Parts are cheap........ Apparently the whole dash has to come out to change this little thing that pushes into the Evaporator, that then tells the Compressor to turn off and on...... Hoping there is a work around this as I do not want to remove the whole dash out of me car, plus quoted some huge as "F" price to do it as well

Good to hear you found the problem.
No warranty? May be worth a look to find out how much a vehicle AC specialist will charge compared to mazda, if thats where you went. That said, when Mazda does work (replacements etc) the reason for the sky high prices (parts and labour) is that the official parts carry a life time warranty, except for wear and tear parts obviously.
Like when I replaced one of my headlights due to condensation (out of warranty) paid full price for the part, they did a 'good faith' discount for labour. Just a thought.