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.
TTL means through the lens. Flash metering is through the lens, using the camera's metering system, which looks through the lens you're using. Non-TTL means the flash doesn't communicate with the camera in that way, and instead uses its own light metering system, built into the flash. TTL is better!lkka wrote: It is a bit simplistic to just say that 'TTL is better', because all studio flashes are not TTL and are often quite obviously better sources of light than a small flash unit made by the camera manufacturer.. TTL is a flash metering technology for cameras-not camera lighting.