Ive been having an issue with my heating for the past few weeks. My Heater blower resistor stopped working so I was gettin no air, I replaced that and now I get cold/slightly warm air when driving. The only time i get hot air is when i rev the engine while stationery however it blows cold/warm air as soon as I stop.
Since this issue I have replaced the blower resistor again for a tested working one, flushed the heater core, replaced the thermostat and bled the system many times.
Does anybody know what the issue might be?