1999 4.6HSE Underheating

Opposite problem to jpr. Lose all heat out of the cabin heater after about 10mins. Temp gauge reads fine, engine seems okay, just air goes cold. I can get hot on demist mode only, but no other setting.

As I said, hot air for about 5-10mins then cold. Will go hot again if I leave the fan off, I guess heat spreading back into the matrix maybe.

I'm guessing one of the heating box motors has gone or something else in the horribly-difficult-to-get-at heater matrix.

Anyone done one of these? I did one on my classic and it took about two days....

try flushing the matrix with a hose pip at the bulk head in the engine bay, then atleast you know it aint blocked or airlocked. then take the blowers through hi to low and floor to window see what happens, if you do each job individually you will know what the problem is/if its fixed and act accordingly! also is the loss of heat on both sides or just drivers?

Good advice, I'll get on that this week. Loss of heat to both sides. No heat on any position except demist, to be honest haven't run the demist long enough to see if it goes cold, it makes such a racket I shut it down as soon as I've cleared.

give it a flush then get it hot and feel the pipes in the bulk head see if they go cold. also if the aircon works see if the motors make a abnormal racket on them too. the blowers sound fine tho as mine were noisy too.

also has it just happened or was it always this way?