I have an R reg Felly, and i could drive it to the ends of the earth and the air coming from the vents is lukewarm at best. Now when i sit in traffic, its gets quite hot, but if i escape the traffic, it starts to go cool again. Also i noticed, that the temp gauge does not move off the bottom mark unless i have been stuck in traffic for at least 15-20 mins (non moving)... Any ideas? Thanks Guys.

Sounds like the thermostat is stuck open, replacment is fairly simple and cheap.

Sure does & there's advice on here + quite straightforward to follow in Haynes manual if you have one

Seems these do suffer from thermostat, issues but as above, nice and straight forward to sort

As others, stuck or missing (yes really) thermostat.

Buy a genuine one though.

Thanks guys, got the full unit on order just in case

Make sure you buy the unit and the housing, as the clips can break and the new thermostat may not fit the old housing!