We have a 2005 Madza 3. Our daughters car. Started over heating last week. We noticed the fan doesn't kick on.

We have replaced the thermostat, ECTsensor. Auto parts store allowed us to test a new fan & control module unit yesterday and it didn't come on.

What test/procedure would a Madza mechanic do next to test to see what is wrong?

Look forward to hearing your suggestions.

Kevin