Hello there new here.

I have a quick one that hasleft my brain baffled to what it could be.

I bought a mark 3 focus 16 plate 4 months ago, drives great, starts and runs how it should, the only thing is my temperature needle keeps dropping when I'm idling. I 1dt noticed it once night when the weather started to get colder as I parked up outside my house nipped in to grab a couple of things and when I came out the needle had come down and there was no heat. 1st thing I thought was the thermostat.

Changed it, bled it, for all the air out, ran heaters on full got warm are but needle wouldn't climb unless was driving and putting power threw it. But it would go all the way to the half way line but as I put heaters on despite driving the needle came back down to cold despite giving sauna heat but then goes back up again, i stop the needle once again comes back down

Asked about, no one knows what it could be. Have ruled out cylinder heads, blocks and head gasket. Put another thermostat on it just in case the 1st was faulty as can happen. This time needle sits just under the half way line. Doesn't come down when driving even with heaters on still sits under ½. But soon as I hit traffic lights or slow moving traffic, my little needle comes down to the quarter and won't rise until I turn blowers off.....

 

Any help would be appreciated, I haven't had It long and already running into a problem no one seems to know... 

 

I'm going to try changing the expansion cap as some say it could be that, if not I'll replace the expansion bottle despite there no leaks or loosing antifreeze. 

I just feel s as it's not holding its pressure as it should, when I first got It, it sat at half way all the time and didn't move even while sitting idle, once it heated up that was it, one simple thing has turned into a night mare. I also called ford and they didn't know and said there problem free cars....help.. 

 

 

Sounds perfectly normal to me.  The 1.6 TDCI is a very thermally efficient engine.  When the weather warms up it'll stay warmer again.

That is completely normal as Tom has already said.

I have a Mk4 Focus 2.0 Ecoblue and I'm lucky to reach 75^oC at anytime during the cold winter weather.