It means there is an error in the ECC. Could be a number of things. It's like a check engine light, but for your climate control. Since your 850 is a 1995, you probably have OBD I and can read the code using the diag. box under the hood. It's located at the front of the ECU box. You will want to read the codes from slot B2, which relates to the climate control. More info on that here: http://www.matthewsvolvosite.com/read-codes-volvo-850
Once you know the code it will give you more about what's wrong.
My 96 did the same thing this summer. Above the front doors (behind the grab handle on the passenger side) there is a tiny hole. Pop off the plastic trim piece and clean out the twenty years of dust with a Q-tip and a can of compressed air. Be gentle! There's a temperature sensor in there with a tiny fan behind it. My ECC hasn't blinked again since I cleaned those two ports.