still need to sort the old heater out though, is there something else that could could prevent the heater fan from working, are the blowers themselves prone to dying?
could be the resistor pack i suppose, can check the motor by jumping it with 12v direct to see if it spins. unfortunatly your blower doesnt look trhe same as a normal mk2 one so i cant advise you how to do this for certain, though there does seem to be a big red and brown wire on there which is where i would start the search
the red and brown wires connect just futher up out of site to the blower, ifs definately connected... gonna go for a blast now see how its doing, i'll pass by a mate who's got a multi-meter.
right mfa isn't displaying oil temp now, it did before... what am I looking for?.. haven't got access to the voltmeter to check those wires yet.. so heater is gonna have to wait
check the green/black wire in the engine bay, if its an 8v the sensor is on the filter housing if 16v its back of head passenger side
just a thought, non-ac fan loom has an earth on a stud on the passenger a pillar, maybe that got disterbed when you did matrix swap?