Overheating When not up to Speed
 

Last night while I was stuck in traffic my FC over heated. Hoses are good the steam was coming resevoir blow off. This winter I had to replace all the belts cause we had a bad cold snap. I waited for it to cool off and by the time I did traffic was clear. I filled her back up with water, got on the freeway and up to speed ran cool as the day I got it. A friend suggested that the radiator might be clogged and needs a flushing or to replace the it all together. The water pump is turning the fan spinning so if you guys have anymore idea's Im open to em. Oh and that fill coolant horn is real joy can't wait to disable that.

I beleive the fsm states that overheating in stop and go traffic is due to a bad thermal clutch unit on the fan.

I'd recommend against disabling the low radiator fan. Your gonna wish that annoying buzzer worked when your on the side of the road crying about a blown collant seal due to low coolant.

Anyways, make sure the fan is in proper working order, it is a clutch type so it could be worn out. Make sure your fan shroud is in place cause it actually helps a lot more than you think with cooling capacity. You can also look at your undertray, although that has more to do with higher speeds: if air diverts under the car rather than through the radiator your losing cooling capacity.

You can flush and fill, use Prestone with Distilled water. THeres also a writeup somewhere (like from 4 years ago) on how to use some kinda degreaser to get the sludge out.

If the engine overheats when the car's stopped or moving slowly, but has no problem staying cool when the car's up to speed, it's almost definitely the thermoclutch on the fan. You can replace it ($191 from Mazdatrix) or convert to an electric fan (cost varies but budget at least as much).

http://www.mazdatrix.com/b9.htm
http://aaroncake.net/RX-7/efanmyth.htm