modeo mk1 heater prob

[klou]

my heater is on full heat at the switch but only warm air flows out then after about 30 secs it blows out cold air am getting normal on the guage, have flushed matrix and rad and changed thermostat can anyone help

[Pheasant]

First, check to see if you're getting hot water to the matrix. It should have two pipes running to it, an inlet and an outlet. These will come off the engine somewhere and disappear into the bulkhead, I should imagine. If only one pipe is hot, but the other is cold then there is a blockage or an air lock. If both pipes are hot then the matrix is working fine. If that is the case then see below:

There should be an air duct below the intake grille in front of the windscreen. Depending on how high your heater setting, the flap ducts air across the heater matrix. So if your heater was set at the halfway mark the flap should be half open allowing some of the air drawn in to pass over the matrix while some comes straight in from outside, thus creating a flow of warm air. If your heater is at full then all the air should be ducted through the matrix. However, if your flap is not operating properly it may not be ducting the air across the matrix, or only a very small amount. If you can remove the intake grille you could have a fiddle with it and try wedging it in position so you get hot air all the time. Then investigate further come the summer.