I have a top-of-the-range 2016 Max.

My engine temperature gauge rarely indicates any temperature. It looks like the normal range should be between two and four bars. But except on the hottest summer days, the gauge never budges from zero.  The Fire dealer tested it and found no DTCS present (I think that means a diagnostic testing code). They then turned off the AC and found, using a cataloguer, the the figures increase OK. They went on to say the car will take longer to warm up when AC is on due to the fan constantly running for AC.

But I find that with and without the AC running makes very little difference.

This winter I have found the cabin temperature take a very long time to warm up and it never really gets 'warm' as you'd expect when the cabin temperature is set too high.

A friend has a Fiesta, but with a lower spec AC system. He says his temp gauge is always between two and four bars.

All a mystery really. Any ideas?

I know this is a long time since the original post, but, not knowing which engine you have, I will state the 'bl***ing obvious'. It would appear that the thermostat is stuck fully open, thus there is constant circulation through the radiator which means that it would take 'for ever and a day' for the coolant to reach normal operating temperature. 

For the benefit of anyone with a similar concern.