Daikin unit changing from cooling to heating itself..???? HELP

[Ash Khan]

Hi All,
We have 2 cassettes & 1 outdoor Daikin unit in one of our lab, we keep this unit on cooling all the time but it’s changing itself to heating.
We have one wall mounted control also with master digital control.
Did anyone can help me to find out what is the reason?????
Many Thanks
Ash

[croc1774]

Check the controller i would bet its been changed to auto mode and not just cooling mode.

[frank]

It would be helpful to have some model numbers and further details of the digital master controller

[install monkey]

weak coil on the reversing valve can cause the system to start heating without warning with no fault codes.
is the 7 day timer programmed beacause this can either start up as last set or start up at a programmed setpoint and mode!

[JoeAT50A]

4 way valve is activated somehow, may be due to Auto-mode, Master should control mode and use lock function so called prohibit function to lock the mode. How is your ambient temperature? Some outdoor temperature will trigger the heating mode.

[Ash Khan]

Dear All,

Sorry about the late reply. I was off for holidays…J
I had a look in the master control and the system was on auto change over, so what I done disable all the auto change over setting to cooling only….Problem Solved.
You guys are GREAT!!!!!!!!!
Thanks for all your support and help..
Ash

[JoeAT50A]

Dear All,

Sorry about the late reply. I was off for holidays…J
Ash

Congrat Ash, not that too late .... just two months.
Hope you had solved this issue two months ago, not recently right?

[Ash Khan]

Thanks Joe,
LOL …..Yes I solved the issue when I received your reply on 06/04/2011 and got busy at work sorry once again and thanks once again for your help.
How’s Air Con work/business in Singapore?
Best Regards
Ash

[JoeAT50A]

Not at all Ash, just kidding.
In Singapore air-con business is good due to hot tropical weather.
In fact need not to thanks me man, I have no idea on Heat pump, we only use cooling only.
Have a good day!