In article .com>,
wrote:

> I'm surprised the fan is mentioned - should it ever turn on at 70mph?

Yep, if the ambient temperature and engine load are high enough, and
especially if the A/C is on (because the condenser throws hot air at the
radiator). The Miata does not have a huge reserve cooling capacity even
when everything is working properly; if it's not, it tends to overheat.

When my fan motor went bad, I saw the needle creep upward on 95-degree
days if I went over 80, or over 75 uphill, or over 60 with the A/C on.
Around town, the A/C condenser fan, which still worked fine, was
sufficient to keep everything cool. On a 1.8, the ECU switches the
condenser fan on at 106C even if the A/C is not in use, just in case the
main coolant fan is fritzed. Handy safety feature, but it sure made
diagnosis difficult. By the time I discovered the bad fan motor, I'd
already replaced the thermostat and radiator, removed the front plate,
and sacrificed two chickens and a goat.

---
Lanny Chambers
'94C, St. Louis
http://www.hummingbirds.net/alignment.html