agree with brother banger. the low voltage could be a sign of a larger problem, possibly in the backplane of your distribution panel. you could have low voltages lurking throughout other circuits in your house. have your panel checked.
your friend who originally checked for proper voltage.....i assume he has a meter. the fuses you are referring to........are they in a disconnect feeding power to the condensing unit ? if so, have him check the line side voltage on that disconnect to verify proper voltage. if the voltage difference is there and you have replaced the breaker feeding it, don't try to run this unit anymore and call the electrician. however, if the line side reads correctly (l1 -l2 * 230, l1-grnd * 115, l2-grnd * 115) and the voltage difference is on the load side of the disconnect (feeding the unit), then the fused disconnect is probably the problem and needs to be replaced. make sure you have a qualified person verify this diagnosis and do the work. it is not your day to die.