puzzling coolant light in '88 80Q

[Tess McMillan]

A couple of mornings ago I was heading into Seattle, car just warming up,
and the coolant light started blinking. The temperature gauge was about
normal. I turned the heater on full blast and headed over to my mechanic,
thinking I had a bad thermostat (since a similar incident happened about
18 months ago.) A few blocks before I got to his shop, the light went off.

We let the car stand idling for a while. Even so, everything looked
normal under the hood, with no blinky-blinky light. We took the radiator
cover off, inspected everything, and probed with a temperature probe.
Everything was normal. I ordered a new thermostat and fan switch, just in
case, and nothing more happened for the rest of the day.

Yesterday I had to go back into Seattle. Got all the way over to my mom's
house without incident. On getting in the car and starting it again, the
coolant light went on again. I had lots of errands, so I continued to run
them, while driving with the heater fan on and windows open. I checked
under the hood several times and everything continued to look ok. Nothing
boiling, bulging, smoking, or stinking. Coolant level OK.

Any ideas what is going on?

Thanks!

Tess
in Bellevue, WA USA
'88 80Q -- apparently the "hot mama"