The blower speed control of our '94 940 with manual climate control has a mind of its own. Cold, it works normally, but in warm weather it quickly sends random and finally no signal to the motor. Is there a resistor pack to check out on a '94, or should I take out the MCC unit and check for cracked solder joints or a gundged up rotary switch? I think the actual blower motor is OK but haven't verified that yet. I'll test it before going into the dash.