Dennis,

Yup, the fan comes on at the lowest speed when the A/C is turned on.  When
the outside air temp is below 80 degrees I don't have a problem with the
constant cycling on and off of the high speed fan vs. the compressor.   With
that info, would "high pressure" still be the cause of the cycling?  I had
the A/C converted to R-134 last summer.  IIRC, it did this before I had it
converted too.

I did replace the radiator temp sensor a few years back.  I wonder if it's
the wrong one?  Does anyone know the correct part number for an '88 with A/C
and automatic?

TIA

Jim