Air Cond stops working when outside temp above 88 degrees.

[knittle]

When the outside air temperature gets above 88 degrees or more my air conditioning on my 98 V90 wagon stops working. The light on the recirculate button comes on amber even though the button is not depressed and the cold air stops coming out of the vents and the air coming out changes from cold to warm/hot air. That is with both the Blower knob and the function selector knob in the "Aut" mode and the temperature dial set at any temperature, usually I keep it at 76. Any help on this weird problem would be appreicatied.