I think it might be a wiring issue. We replaces the fan and fan module. No luck. Fuses replaced.

When it is over 65 degrees outside the car overheats and fast!!

Can't run the AC, makes it worse.

Turning on the heat helps ... but not a good fix when its hot.


Any suggestions? Even the Madza dealship can't figure it out.

 

Stupid question but has it got water in it? Does the fan kick in at all?

 

Water yes. Just had all the fluids replaced.

Fan is not kicking on even when its overheating. You know its about to overheat even without looking at the temp gauge ... it blows in hot air in the AC/Heat vents.

 

It could be the temp sensor, however that also drives the gauge. There is a relay that is controlled to energize from "a module" probably a body control module to turn on the fan. I'd agree with wireing issue. You should get at the least a Haynes repair manul to track the wireing down.

 

I would think that the most likely issue is the water temp sensor that drives the fan to switch on although normally as long as you are driving and not sitting idling in traffic cars dontt normally overheat these days.

other things it could be - a blockage / airlock in the water system, thermostat or water pump.

 

It gets worse when it's hot out (drove it fine all winter, today its 77 deg and it overheated) and even more so when stopped in traffic.

The temp sensor was replaced.
We have the Haynes manual ... did some rewiring and so far no luck at all. Getting really frustrated!

 

Check your grounds?

 

Now to troubleshooting this. First, when the temp is up, is the relay energizing? Yes, is the power from the relay contacts there? Yes, is the relay contacts burned? If you have the relay energizing, is the power being switched to the fan from the relay? If no, then you will have to diagnose why you don't have voltage to the relay. If the relay is energizing, do you have battery voltage at the relay contact? If not, check fuse again, if you do is the power switching to the fan? If so, and the fan won't turn, check ground. If you can use a voltmeter check the ground at every point that circuit is grounded, not just clip on end to the negative terminal.

 

The fans are controlled by the PCM/ECU. If you take it to a Mazda dealer they can use their diagnostic computer ( IDS or M_MDS) to tell the PCM/ECU to operate the fans, then you can see what's going on and help in the diagnostic procedure.