Mitsubishi AC Repair at Pelican Waters, QLD

Attended breakdown today for an elderly lady at in Pelican Waters. Initial report from the client stated that the air conditioner is 1 year old. About 3 months ago, a builder did renovations on the building and to paint behind the Mitsubishi Split System Air Conditioner he had professionals uninstall the Aircon and once all painting had dried, the builder had the installation experts reinstall the split system.


As soon as I arrived I found the system was first of all, designed too small for the area it has been installed in. Second thing I noticed was that the system error codes were flashing. 1 timer flash and 6 operation flashs. As soon as I noticed this, I contacted MHI technical support to get their error code list but unfortunately the technicians were not available at the time.


To start the diagnosis off, I isolated the outdoor weatherproof isolator and went through the entire system to ensure all components were electrically safe. Make sure there were no shorts or dead animals inside the unit. I metered the motors in the system and tested earthing on all components. System was testing electrically safe and motors were testing very well.


I then went to the indoor unit and pulled off the front fascia of the air conditioner and inspected again for dead animals and also tested motors and made sure everything was electrically safe. Everything was coming up good.


I then turn the main power isolator back on and tested voltage going into the unit. 240V, everything was good. Outdoor was also sending 240V to the indoor unit which is great and the communication wire was sending the correct DC voltage between the indoor and outdoor units of the air conditioner. 


I went inside and ran the indoor unit on the fan only setting. Everything is still working as it is supposed to. I opened up the pipe cover to find a poor copper pipe connection. There was no insulation, only duct tape around it. It was at that point that I started doubting the refrigeration side of things where the recent installers did a good or bad job.


I immediately got my gauges out and threw my gauges on. The system went straight into negative pressure. I straight away seen that the installers did not open the service valves after installing it and this elderly lady has been trying to run this Aircon with closed valves.


Due to me still not trusting these installers, I ran nitrogen through the system and pressure tested all of the installers connections. All of them were good so I fixed up the insulation, put the system on vac and brought it down to 500 microns. Once it hit 500 microns, I opened up service valves hoping that there was still refrigerant in there. As soon as it started hissing, I was pleased.


After opening the service valves, I ran the system testing pressures. System is now running perfectly.

Tip for clients: Just because someone says they are a technician, does not mean they are professionals.


Tip to HVAC&R Technicians: double check your work even on a late Friday afternoon.