Yes - we did not have it on the M60A1 or A3s plus the M1IPs and we did just fine with these tanks in desert environments and in South Korea. At least on the M1A1 we could turn on the overpressure system and this would help out.Like shown for example by Spain (Which operates them in on of the hottest places on earth) the normal funtion of a Leopard II is not compromised by heat so including a normal air condition for the crew makes the Leopard II capable of operating in hot conditions.
It is not as if it could not operate without air condition but constant high temeperature inside of a tank just reduces crew performance.