Most block walls in Arizona were built for evaporative coolers so they are not insulated.
Most block walls in Arizona were built for evaporative coolers so they are not insulated. An evap will perform well without insulation, but AC systems are the exact opposite.
Block Walls Hold A Tremendous Amount Of Heat, And Pump It Into The House Long After The Sun Sets
As the day progresses, a block wall stores increasing amounts of heat, and the heat penetrates all the way to the interior of the house. After the sun sets the air cools outside, but the block pumps the heat that it retains during the day, into the house. This causes discomfort and the AC to run late into the evening.
A Foam Sealed Block Wall Slows Heat By 82%
Foam insulation slows daytime heat penetration into a block wall, preventing it from penetrating all the way into the interior of the house. This keeps the rooms comfortable and causes the AC to run less.