Could a blocked heater matrix cause overheating? The inlet heater hose is hot and the outlet is cold with cold air out the heater vents. I heard you reverse flush the matrix but if this doesnt work what else can i do? Also how hard is it to get to and is it much work gettin it out?

 

Yes it can.
We had that happen to a car last week.
You could try putting the heater on high,while idleing the car.
Then squeeze the hoses going to the matrix.
This normally works.