coolant fans not turning on early problem. ive found lots of threads related to this problem but with no solutions. at warm up temps climb up to 230-240F and fans finaly kick in then temps drop down to about 209 both fans shut off then same thing happens again. while this happens the OEM temp gauge stays at half point without climbing at all. ive tested the fans by grounding the TFA+ground and by grounding the test ground wire (blk/yellow) down by the ECU and the fans work fine. ive grounded the thermoswitch connector and i can hear the relay click. ive tested all four relays by applying 12V to them and checking continuity across they all read about 4 OHms. fans come on when a/c is turned on. the fan relay harness connectors were full of crud but they have been cleaned and make good contact. each fan has been tested but per the manual you can test the three different speeds (low med high) when i tested them both fans work on high but seem to turn on low only when tested at low/med speed. any suggestions on where to go from this point?
the following are new parts recently installed.

aftermarket temp gauge (sensor installed at thermostat housing)
new OEM thermostat (tested per manual)
new OEM thermo sensor
new Mazda FC thermoswitch (supposed to turn fans on earlier)
50/50 mix coolant
new alluminum AST

 

i had the same problem... what i did is go buy a new relay.. and check again and then it kick on...

 

i was thinking of that too but wasnt sure since all realys checked out good( click). i applied 12V across the two spades labeled coil and measure continuity across the two other contacts (no and com they measure about 4 Ohms).

 

damn this is werid.... well if i thinkin of something or see something that will help you out ill be sure to pass the info.. good luck with the fix