1 CostHelper readers report costs of $1,000-$3,700 for major air conditioning repairs, with an average of $1,829. 2  Installing air conditioning in a vehicle that doesn't have any can cost $1,500-$4,000 or more, depending on location and the vehicle's year, make and model; luxury vehicles can cost even more. This generally includes replacing a few parts like hoses, sensors, or either the compressor or condenser. 2  CostHelper readers report paying $171-$727 for minor air conditioning repairs, at an average cost of $488.
TTL stands for Through The Lens, and in the case of SLR metering, it indicates how the light is measured--that it's the light coming through the taking lens, rather than, say, an exterior sensor.
This allows complex circuits to be built from simple components in a sort of building blocks fashion. The TTL (Transistor Transistor Logic) circuit family is one such circuit family. TTL circuits use two voltage levels, 0 volts and +5 volts to represent the two binary digits 0 and 1 respectively.