as already said check water level! and if you have run van low on water at sometime - you could have air-lock in cooling system and you will need to bleed it..start engine and let it tick over ,take cap of header tank and then undo and loosen (do not take off )bottom hose /clip on radiator till water trickles out ,keep filling header tank till water is running freely out of bottom hose... and make sure the heater is turned to red.and blower on.... after a while do bottom hose back up check header tank water level ..put cap back on ...check if heater is hot...and keep checking temp gauge (should not go above normal) if its still no good fit a new thermostat first (its the cheapest thing to replace)
tony
February 2009