I arrived in the homeowner greeting me at the front door I asked her how things have been and she told me that her system keeps shutting off on her on high head pressure per code. Offer thermostat. This is a Infiniti carrier system It is 16 years old well pass its life. I highly recommended brand new system. Homeowner would like to wait till this finally dies out Putting my gauges on the system I have high head pressure over 450 and now I understand why it is going off on high head pressure after looking at the condenser it is extremely dirty I got approval for a maintenance plan and an in place cleaning I took all the doors off the side of the unit and use condenser foam cleaning chemicals and removed all the dirt and debris without doing damage to the system Some of these fans are falling right off due to the age again I highly recommend a new system After cleaning off the system and starting it up, the system is within normal specs at this time. I am monitoring it for 2