Mitsubishi P5: the drain protection stopped the unit before water did

What Does Error P5 Mean?

P5 is a drain protection stop on a Mitsubishi Electric indoor unit. The control saw the float switch rise, or it saw the drain pump circuit fail to respond, and it shut cooling down to keep the condensate tray from overflowing. The code proves water did not leave the tray fast enough. It does not name the blockage, the pump, or the switch as the failed part. Applies to: Mitsubishi Electric indoor units that publish the P-series protection table, including Mr Slim cassette, ducted, and ceiling-suspended indoor units P5 is read here from the Mitsubishi Electric fault-code reference for the indoor families that publish the P-series table. Wall-mounted units without a condensate pump do not carry the same detection, and a Mitsubishi Electric controller fitted to another manufacturer's indoor unit will not follow this table. Match the code to the indoor unit model on its own rating label rather than to the outdoor unit. Owner-safe checks: Switch the indoor unit to fan only or off so the coil stops producing condensate, and leave it that way until the fault is assessed. | Look at the visible outdoor end of the condensate line during a period when the unit had been cooling, and note whether any water discharged. | Photograph the controller showing P5 together with the indoor unit address, and note the outdoor temperature and humidity at the time. Qualified technician: Checking the float switch, testing the drain pump circuit, and clearing a condensate line inside the indoor unit require the electrical enclosure to be opened, which is qualified service work. | Water staining on a ceiling, a wall, or an electrical accessory near the unit is a stop condition. Isolate the indoor unit and arrange service rather than running it to see whether the code returns.