[petet16]

Not sure tbh, I usually set the temp to about 19'C, then set both functions to auto and leave it to do it's own thing, what does confuse the system is having a window open.

You can make the system do a self test by keeping the auto button pressed and turning the key to position 2, then keeping the auto button pressed let it run through it's self test, you'll hear the servos running, and various clicks, when its finished it will show any fault codes, it could be you have a sensor down perhaps.