All car rentals are off-property in PHX; I cannot recall if the FB lines are at the counters in the terminal, or out at the lot. If the FB lines are at the counter in the Terminal, there will be some variables.

T2 = UA/US/CO/AS is a small terminal, so the line shouldn't be that bad. Cross the road outside baggage claim to the median, and locate the blue diamond.

T3 = DL/NW/AA is midsized, so may be more of a problem. The blue diamond is directly outside baggage claim, IIRC.

T4 = HP/WN is the busiest terminal. If the FB line is in the terminal, get in line for the car rental before you get your bags; bags tend to take awhile due to volume. Exit baggage claim and cross the road to the median and the blue diamond sign.

Enjoy AZ!

Bob