We appreciate the opportunity to assist you with your vehicle needs. In order for us to properly diagnose a condition and provide an accurate estimate of repairs it is our shop policy for us to scan for all stored and history codes even if customer has already done so. It can be a slippery slope when a vehicle comes in pre-diagnosed. We have encountered on numerous occasions, where there was more to the reason for the engine code that required further digging. A vehicle owner may not agreed with our precautions, but especially when dealing with vehicles having 193,000 + miles, anything is possible. In regards to the AC, we did perform a A/C test which included bringing the refrigerant level to the manufacturer specs along with injecting oil and leaking tracing dye. We immediately detected a severe leak at the systems evaporator core, which could take days or hours before all refrigerant leaks out. We will admit we left the AC valve caps off in error. (We are human!) But refrigerant does not leak out because the valve caps are missing, the dye trial clearly shows the culprit. There are times that we have to be the bearer of news that a vehicle owner really does not want to get. All charges were explained prior to diagnosis/work being performed. This situation appears to be one of those times.
I also felt the price quoted for replacement of rear rotors and pads was too high.