My heater is just blowing out cold air.

If I turn it to max once engine is on it will blow lukewarm for a few minutes then go cold again, any other setting just stays cold...any help would be appreciated?

That may either be a blocked heater matrix or airlock. Has there been any work done on the cooling system recently .Check that the expansion reservoir doesnt have the silica bag in it. If it ruptures then it will block heater matrix. Think they have Mit Silicat on them. Have read that if may also have G13 on tank

Alasdair

I had this on mine, but I believe the tell tail signs it's the matrix being blocked, is that the passenger side is warm and driver side hot. It's pretty reliable how it faults, not on and off.

Outside air temp has an effect though, the blocked matrix really shows itself on cold days.