Nah, panel van with a bulkhead - same matrix as a LWB minibus heating a far smaller space through less ducting!

I went to sleep in mine with the engine running and the heater on three quarters once and dreamt my house was on fire.

The new ones had a curtain heater type affair behind the driver, the cockpit was boiling hot but the passenger area was freezing

Removing the heater matrix in most cars is a massive job. Not so in '74-'94 Polo's - virtually a quick release design, it slides out in minutes!

Quick flush by putting a hose pipe to the inlet, should clear it out if it's blocked (and indicate it's condition).