Per my 96 owner manual;

"The REC and ACC OFF lights will flash for approximately 20 seconds if a fault is detected in the Electronic Climate Control (ECC) system. If this flashing recurs the next time the system is switched on, the climate control unit should be checked by an authorized Volvo dealer."

Last time the lights flshed in my car, the temp sensors located above the "Oh Sh*t" handles in the drivers and passenger comparment had filled with dust. The dealer used a can of compressed air - like the kind used for computer keyboards - to blow the sensors out.

Good luck.

Oliver

Over a million Volvo miles and still smiling....