Whiny erratic 1990 240 auto transmission

[Black240NH]

I have a 1990 Volvo 240 wagon with 137,000 mi (yes, that’s true mileage - I’m the second owner. Bought from couple who only occasionally used it in good weather - never winter)

The automatic transmission has gotten wonky and I’m looking for an answer, if possible, that lies between TruGard and a total rebuild.

At times it behaves almost normally, whining a bit as it approaches its normal shifting points; at other times it doesn’t whine at all.

THEN, there are times when it shifts at 40+/- and then not again until 72 +/-, protesting mightily as it approaches those speeds. It might do that for three or four days and then, with no warning, revert to normal or more normal behavior.

What’s going on? Is it fixable? How long do I have? Could it be something other than the transmission that is sending the wrong message?
Thank you.

[jimmy57]

If it is whining the most likely cause is blocked filter. Service the trans filter by dropping pan and replacing filter and the gasket for pan and filling with new fluid. Holding out shifts is often due to sticking throttle cable for trans. You will see it as bottom cable on the throttle cable spool on intake. You can pull it by hand and see if retracts smartly by way of the spring in trans. If not then lube the cable with WD-40 and then some oil to see if frees up.

[Black240NH]

Many thanks. I'll get that done next week and let you know how it goes...