Our van has been acting up since last year with eratic heating. Although the guage shows the engine has heated, it takes approximately 25 mins for warm air to blow. I've checked the water levels and all seems OK. Today, the guage soared to high and the temp light came on. When the heat was cut off, the guage leveled out.

Does this sound like a thermostat issue? Any help will be greatly appreciated.

 

If the coolant is not low and the water pump has been changed, I think the water pump may be your problem. The pumps with plastic impellers have been failing. I had the same symtems and it was the pump.