sentra heater problem

[2.4niz]

97 Sentra gxe. the heater just stopped working a few days ago and I am lost. took the heat control box out of the dash, the plastic helical cut gears are working fine, moves the blend door with no problem, but I have no heat. Just wanted a few opinions before I start taking anything apart, thanks!

[2.4niz]

ok, took off the heat core outlet hose with engine at operating temp, after a few drips, no coolant flow whatsoever, reconnected outlet, let run for a minute then took off inlet hose, no flow from that either... I would assume that leaves the water control valve, but my haynes manual doesn't mention a control valve at all, anyone know where it is?

[carmo]

When you took the heater hoses off, you should have made a hell of a mess. I would suspect low coolant level for no heat. With the car cold, you should have coolant to the tippy top of the radiator. If not, then I would start by adding coolant and bleeding the air from the system. You say the blower motor works and the blend door works and the mode door works. There isn't much left. Does your car have that valve that cuts flow through the heater core? Is that what you were talking about before?

[2.4niz]

ok, I have no flow through the radiator. got the car to operating temp, full pressure, top and bottom hoses hot, twisted the cap off, and nothing. no fountain of water, nothing. watched the coolant for a minute, and no movement whatsoever. apparently something is blocked, but how do I start tracking down the blockage?

[navysnail]

check your thermostat, it might be stuck closed.

[2.4niz]

I have full pressure, and the top and bottom hose are hot, I dont think it can be the thermo

[navysnail]

see if the lines going to the heater core from the engine are warm as well when you turn it on.