View Full Version : split units

31-12-2010, 03:30 PM
I am wondering about the pc boards that control them. How do you test if the pc board is faulty. And what basic sensors will a split unit have that I should look out for?

I am new at this game, but I would like too become a Great tech. Thanks for all the help. :)

31-12-2010, 04:22 PM
I normally check each individual item, for instance i remove the fan wiring (first make sure you have the same voltage as the fans) and connect a test lead up and see if they power up. Then i do a quick compressor direct current startup and see if it works. Obviously if they all fine there will be a problem with the pc board or fuse or sensor. process of elimination always works, but takes time.

31-12-2010, 04:27 PM
Hi Johan2.

A PC board is basicaly a microprocessor which handles information from inputs and gives outputs as programed on them. For you to be able to determine if the PC board is faulty you need to know what value of the data is sent to it via inputs and what you should expect on the other end of the out puts. For example if your room temperature set point is 22degC and your temperature is measured to be below set point way out of your dead zone or proportional band which in most microprocessrs used on split units is usually +/-2degC then you can decisively conclude that the PC board is faulty. There are a number of other factors you will need to look at as well like the resistances of your temperature probes etc which you need to know before you can condem a PC board.

www.isentropictemptech.com (http://www.isentropictemptech.com)

charlie patt
01-01-2011, 12:25 PM
this is a issue that is always been a bit of agrey area i suspect we have all been caught by a daikin with acommunication faulght, firstly i always check the incomeing supply then thermistor resistances depending on fault code if invertor i carry out a invertor check then a comp ohms test then check in out supply to each board to sea if each unit are talking to each other if all ok we have made a tester to clip to each board on a mhi and a daikin to test each area however usually i have found board failure due to someother fault ie a fan to earth . then of course we have the cost i was quoted the other day 237 pounds for a outdoor board on a daikin on a 7 year old product when a complete system is available for 350 out of the same manufactuer so damed if you do damed if you dont any ideas fellow engineers?:)