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"-stat" = switch. So, a temperature operated switch is a thermostat. It can be a thermistor or other device, as well as a temperature operated modulating coolant valve.
After testing every fuse and relay I tested the temperature sensor and all checked out. I though for sure it’s a ecu issue. Then I decided to go through everything again. I know for sure the fan works because I bought a new one. So I started with power and ground again. Had a strong 13 volts. Then went to ground wire. After checking ground it seemed fine. But when I checked a different ground wire it was twice as strong on the Multi meter than the ground for the fan. So I traced the ground wire down and when inspecting connection there was very little contact due to paint around the bolt. I cleaned the paint off the area and everything worked like a charm. I guess the original threads inside the bolt was not enough ground. So cleaning the metal was all that was needed to give that perfect contact. Just a heads up if someone ever has any issues in the future. I know for sure if the dealership was to work on this they would have charged you for multiple parts and lots of labor. No codes were present so hard issue to find.
So I traced the ground wire down and when inspecting connection there was very little contact due to paint around the bolt. I cleaned the paint off the area and everything worked like a charm. I guess the original threads inside the bolt was not enough ground. So cleaning the metal was all that was needed to give that perfect contact. .
Has the vehicle ever had any panel & paint repairs before?
Seen plenty of earth issues after paint repairs, they paint over the earths and don't clean the threads or brackets upon re-assembly.
After testing every fuse and relay I tested the temperature sensor and all checked out. I though for sure it’s a ecu issue. Then I decided to go through everything again. I know for sure the fan works because I bought a new one. So I started with power and ground again. Had a strong 13 volts. Then went to ground wire. After checking ground it seemed fine. But when I checked a different ground wire it was twice as strong on the Multi meter than the ground for the fan. So I traced the ground wire down and when inspecting connection there was very little contact due to paint around the bolt. I cleaned the paint off the area and everything worked like a charm. I guess the original threads inside the bolt was not enough ground. So cleaning the metal was all that was needed to give that perfect contact. Just a heads up if someone ever has any issues in the future. I know for sure if the dealership was to work on this they would have charged you for multiple parts and lots of labor. No codes were present so hard issue to find.
I am having an overheating issue as well. Can you help by identifying where this painted bolt is located? Perhaps take a photo? I hope I have the same problem. This will save me $2,200 in dealership repair.
I just wanted to chime in here as I was just about to pull my hair out, and give Mazda some more of my hard earned money for such a ridiculously easy fix BUT hard to find issue!! Started with A/C blowing warm air on a trip back from camping. Followed up with a trip to Mazda to confirm, condensor had a hole it it. Mazda did not mention my fan wasnt working atthis time. Replaced the consensor myself for $250 CAD. After this i noticed the fan wasnt working. Found voltage going to fan, so figured fan motor was bad, replaced it, still didnt work.. after a few days of checking thermostat, coolant temperature sensor, buffing ground contact points around the engine bay.. found a BAD GROUND on the radiator/condensor cooling fan, which I believe took out my A/C air conditioner condensor (hole in the line likely from overheating/overpressurization). Rewired the cooling fan ground to a SOLID known good ground, and it works again! Note that just taking the old ground off and buffing the metal WAS NOT ENOUGH! See pictures for location of BAD ground (right behind driver side headlight), and how I wired the new good ground (still needs to be routed pretty, but works!) Hopefully this helps some other people!
While you are at it you should add a couple of ground to engine and ground to other chasiss point. As well I highly recommend to install an addition positive cable from the battery to the starter.
Next time disconnect the fans and jump them directly to test their function.
In a pinch you could have left them disconnect and ran a couple of lkeads grounding them and powering them for the long drive. PIA to pop the hood each stop and disconnecting the ground to shut off the fan but at least you would have them running. The AC on some system will not function if the fans are not running.
2019 Mazda CX-9 Cooling Fan Issue
Where is the painted bolt located?
