IT'S COLD IN MY DEFENDER...
Well, It's not actually, it's rather warm. But this is a common thread in any Land Rover forum (in the UK anyway....). So in a moment of boredom here I am writing about how to warm up the inside of your cab.
Two things to think of, what heat goes in, and where are the draughts. It's rather pointless ploughing in the heat from a reasonably warm engine if your bulkhead vent seals let in a draught to freeze your testicles numb above 15mph. So I started with the logical bits.
Door seals and bulkhead vent seals need to fit, If you replace the door seal and it still leaks then you need to refit the door. This could mean that you need to change the door hinges on an older vehicle as they tend to let the door sit away from the seal when they wear.
If you have a utility defender with no floor covering then this is going to be harder for you, you'll probably be getting a breeze from the floor plates gap, or maybe even the fact you don't have a roof..... I have a Wright Off Road kit in the front of the 110 - excellent kit - this cuts out not only noise, but any draughts. I drove without it for a while and got a cold left shin from some draught or other down there.
Windows, make sure the seals fit, if not, replace them you tight git. The rear sliding windows seem to let a breeze in from new, this is one that I haven't managed to fix yet (but then again....I sit in the front seat, so no urgency...)
Then I moved onto the issue of the heat coming in
Engine Thermostat - to cut a long story short, you can fit an 82 or an 88 degree stat to the 200tdi. I chose the 88 after a lot of online discussion and consultation with the dealers. It runs better, sits exactly half way on the gauge and fuel consumption sticks at about 30 to 32 mpg.
Ensure your radiator works, Mine was just ok, the bottom 2 inches were always cold and the fins were damaged. I replaced it eventually, but not for the reasons were talking about here. I also flushed the heater matrix, well worth it as they do seem to get a bit clogged up. Just put a hose pipe on the end and flush it out. That's them below.
Force air in - Does a wing top air vent make a massive difference....NO, does it make any difference... YES, a bit. So for the cost of about £10 I fitted one. Above 20mph you should notice a difference in air coming through the heater. Before you fit it, get one of the kids to stick their arm down the hole and pull out all the old leaved and mud, it will help......
Adjust cables - Wiggle these up & down and look for where they move in the passenger side of the engine bay. they must move the whole range and operate the lever at the other end the full range. If they don't, then they will make any other improvements useless. Spend the time getting these right, its worth it.
Finally, remove the feet covers down here (below) It's much better without them.
Failing all that, and your still cold, buy a space heater & get it fitted. I live in the North East UK, It was 3 degrees last night and at the end of a 9 mile run to collect my son I had to open the window as I was too warm with the heater on full, wearing a t-shirt and cardigan. Bare in mind a 110 is big, it takes a little while to get the heat circulated inside.