Ka Sport Intermittent Heater Fault

[KayeSport]

Hi,

Got a 2005 Ka Sport SE and I am having trouble with the heater.Replaced the coolant and now have this problem,which has been going on for a month now and want it sorted before winter sets in.It can be on full hot then all of a sudden start blowing just tepid/cold air.After a while,sometimes the following day it will all be fine again.

Replaced the HCV with a genuine ford item,Thermostat unit again with a genuine ford item.Swapped out the heater control panel,and also put in a "T" piece bleed valve in one of the pipes that go into the heater matrix to allow for any trapped air in that area to be released easier.Flushed out the radiator and the heater matrix with a hose till all the water runs clear.Squeezed all the pipes to release any trapped air.I"m just wondering if it is an airlock and now whether to take it to a garage and have the coolant drained out and then vacuum refilled to be absolutely sure theres no air trapped.The cooling fan does operate okay when its stationary,but don't know whether its running whilst im driving it at any time.Anyone had similar issues?

[KayeSport]

Looks like its all cured now.Had the cooling system drained and vaccum refilled.Heater working spot on,fingers crossed