MY A/C DOES NOT WORK IN SPEED 3 AND 4. THE RELAY CUTS OUT AND ONLY RESETS TO ALLOW WORKING IN SPEED 1 AND 2 PROVIDED I RETURN TO ZERO.

ANYONE CAN HELP, I DOUBT ITS A SWITCH PROBLEM, AS THE MOVING PARTS IN THERE OR LACK OF THEM SURELY CANT BE CAUSING THE FAULT.

I SUSPECT EITHER THE HELLA RELAY OR RESISTANCE SWITCH AT A/C BLOWER.

PLEASE HELP.

Most likely a bad blower resistor located to the left of the blower motor mounted to the case held in by 2 screws as the resistor coils are inside the case for cooling. You'll need to remove the knee bolster to access it and it'll come out easier if you first remove the lower right torx screw so can slightly move the dash away for clearance. I assume you have a MCC car? If so, the part's not overly expensive compared to the electronic ECC version which runs about $110. With ECC, they usually just fail completely.

Maurice,

the firs speeds go throgh one fuse(I think its #5) and the last speed through #31 look at fuse box. I had some strange problems and they went away by replacing the two fuses with new ones. The higher speed does not go through ballast resistor that the lower speeds do and does why it takes a separate fuse for the straight current. The system also has some relays that control the current. Go to volvospeed.com and under bay 13, you can find instructions on where some these items are located.