Hey guys I've been trying to sort my heater out for over a year now (only puts out lukewarm heat) and have decided to just go ahead and pull out the heater box as I'm out options and it's getting pretty bloody cold outside lol. I guess besides replacing the core this is a good opportunity to put in a manual pedal box, a new ac evaporator and to inspect all the blend motors/clean all the dust crap off the cabin fan.

But before I jump into it all and start pulling the car to bits I'm curious to know if a blend door motor can break without showing the fault code? (as mine doesn't show any fault codes) and if a heater core can be stuffed without leaking if anyone knows because the core has hot coolant circulating through it (and no leaks!) but the heat obviously isn't reaching the vents..

So either the core is passing the hot coolant through and not conducting any heat for some reason or it IS conducting heat and it's the blend door that's stopping the heat from reaching the vents (despite showing no fault code)... or it's something else ridiculous lol like the control module itself cause I've heard even those can cause issues something or something.

I'm not sure whether to just go ahead and take the gamble or not.. last thing I wanna do is pull everything apart for no reason, find out the blend door and core are fine and it's infact something else like the module or an invisible fairy perhaps..

When I bought the car the cooling system was neglected and I flushed out rusted water from the core and radiator so I'm really hoping it's the core. I'll take the dash out job anyday over the years of insanity this has caused me

Put a radiator/cooling system cleaner following instructions on the bottle (the one I used I had to drive the car for 200kms but I done bout 300kms to make sure) then drain flush n refill. Could just be a heater hose built up with crap and not allowing hot water thru? What about your thermostat? Not sure if this will effect the heaters or not or the valve/tap that's in the engine bay attached to the heater hoses? Maybe fubar

The blend door flap shaft can break. So therefore blend door still moves but the flap dosent between hot and cold. Then no error codes. E3. You may hear it moving around the dash if you throw the car around some corners.