Defender 110 Heater

The guy I bought my landy from fitted a new heater which works as it should except when I move the lever to the cold position it stops the air flowing from the vents inside and the blower motor is put under strain. Any ideas why?

it's ****ed

What ****ed as in buy a new heater ****ed?

Sounds like hes just set it up wrong


Lynall

Sounds like he just hasn't set up the cables correctly.
When you look at it the Defender heater is simplicity itself and a few minutes adjusting the cables so flaps are open or closed when they are meant to be makes the world of difference. This one sounds a little different and I wonder if the levers are actually operating the correct cable (i.e. the hot/cold lever is adjusting the dashboard vents?).

The heater-is a metal box with a fan at one end, a matrix in the middle and an outlet through the bulkhead at the other.
The fan motor lever not only operates the motor but when pushed fully up closes the flap at the bulkhead stopping any air passing through the heater-box. The temperature lever operates a flap that allows air to pass either through the matrix (hot), bypass it completely (cold) or a mixture of the two. Lastly the air output lever operates on the flaps mounted in the lower dashboard section and allows air to exit either through the lower dashboard or windscreen vents.

I think it has probably been set up wrong too so I shall get stuck in now I know how its supposed to work. Cheers!