Heater is blowing out cold on my 1999 chevy venture

I couldn't find a heater hose diagram specific to the 1999 Chevrolet Venture with rear heat and air, but I can give you the general location of the heater hoses and how to identify which ones go to the rear heat. The heater hoses on a 1999 Chevy Venture are located on the passenger side of the engine compartment. There are two heater hoses, one that is hot and one that is cold. The hot heater hose will be connected to the heater core, which is located under the dashboard. The cold heater hose will be connected to the engine. To identify which heater hose goes to the rear heat, you can look for the hose that is connected to the heater core outlet that is labeled "Rear Heat." The other heater hose will be connected to the heater core outlet that is labeled "Heating Core Inlet." Once you have identified the heater hoses that go to the rear heat, you can reconnect them to the heater core. Be sure to use new clamps when you reconnect the hoses. Here are the steps on how to replace the heater hoses on a 1999 Chevy Venture with rear heat and air: Disconnect the negative battery cable. Drain the coolant from the radiator. Remove the heater hoses from the engine and heater core. Install the new heater hoses. Fill the cooling system with coolant. Reconnect the battery cable. Start the engine and check for leaks.

Hello, You need to open the two breeder valves and make sheer ur getting coolint throw ur hoses. And make sheer you have no air throw your lines.

Most common problem is a clogged heater core....flush it
it might take a few tries to get it clean

needs the water system back flushing out, heater being cold is its blocked up some time a few back flushes and forward flushes with a hose pipe should free up the dirt inside, same with the engine and radiator. there are meany videos on you tube to help you understand how to back flush you engie. but do the radiator and engine and heater separate so the muck does not go back into the engine.

Usually a blend door problem, either the control or the blend door itself.

Could be the Thermostat that causes such a problem. Try to change it with new one. Good luck

how are you looking at your thermostat with the car running its not possible unless you have xray vision check you water level cars have to warm up for you to get warm or hot air

Chevy made some weak intake gaskets on 3.1 and 3.4. My guess is that the intake gasket is weak and/or leaking and it is letting pressure out somewhere. At idle maybe the system pressure is to little to push hot coolant into the heater core.

check the vacume / or the vacume regulator for the door exchange from hot to cold there might be a vacume problem.

check your coolant level...if its too low then it will not flow through the heater core correctly to generate the heat.