Absolutely all units are checked up on operating capacity. For example internal block is filled with coolant to check the hermeticity and absence of hydraulic noise during the pass of Freon through the heat exchanger. Further unit is vacuumized and connected to the model of external unit and is operating for 20 minutes. During the test all modes and remote control operations are checked. Operating units is checked up for such parameters as noise level, power consumption, isolators. External units are checked up the same way.
Also, all new models are passing 3 special tests, developed by Mitsubishi Electric: operation with simulation of dirty filters and heat exchangers, operation in salt shower, operation with external unit permanently located under direct sunlight.
Every day one or two air conditioners are checked up with more severe tests in special plant laboratory where the compliance to all parameters described in specifications is identified.
Simulation of dirty filters and heat exchangers
It’s well known that filters and heat exchangers must be cleaned occasionally. However, not everybody are doing it. As result the vaporizer can get rimed, and compressor – overheat. Mitsubishi Electric insistently recommends to observe the rules operations, but considers various out-of-order situations. In the first test heat exchanger of internal and external units is partially blocked, thus simulating the situation with dirty filters and heat exchangers. Testing is done non-stop for 800 hours. During this time air conditioner must not overheat or turn off.
In the second test corrosion stability of the air conditioner is checked. External unit is located in the camera with salt shower, where it works 300 hrs. After such work there should be no corrosion marks on heat exchanger, impeller or other details. Of course, there could be no damages of electrical components. That’s why Mitsubishi Electric air conditioners even without special modifications have proved themselves excellently in maritime zones.
It is mentioned in air conditioner set up manual that external unit should not be located in sunny place, for the body not to get warm under the direct sunlight. Of course it is recommended not to do this, but sometimes this rule is neglected. Mitsubishi Electric has foreseen this case too. In third test external block is located under the source of infrared radiation, which imitates sun. Air conditioner must operate for 1000 hrs. without overheating and emergency shutdown.
Operability check-up of external blocks in conditions of strong air flow – simulation of strong winds.