How to make heater get hot in 94 chevy caprice. replaced heater core and control valve on heater hose. gets warm, not nearly enough. bled system too. still wont get hot. also replaced thermostat. any other ideas?????????

Either your heater blend door is failing, your core is plugged, or you have poor coolant circulation. checking the temp of both heater hoses will rule out the core usually. (Warm engine, heater ON, both hoses should be HOT and near same temperature). If 1 hose is hot and the other cold, your core may be plugged. If both hoses are HOT, and still no heat inside, your heater box is likely not directing the warm air properly on the interior. If neither hose is hot or warm, and heater is ON, your heater control valve should be checked to make sure it is flowing coolant to the heater.

If all THAT seems to pass (heater valve definitely open) an d still low or not heat inside and both hoses the same, your water pump may not be making enough flow to feed the engine and the heater. Typically if this is the problem, holding the engineat high rev (3000+) for 5-10 minutes will cause the heater to warm up mostly, and then dropping the RPM to 1000 or 1500 you will feel it cool off rapidly. If that is the case, you will need cooling system repairs.

1: not enough liquid in the system (air in the heater core)
2: inoperative heater valve not allowing hot liquid into the core
3: hot/cold blend door in the heater box stuck on cold
4: clogged heater core
A clogged heater core will have one hot hose and one significantly cooler hose at the firewall connection; easily tested by hand. a good core will have both hoses very hot to the touch when the heater is on full blast.
Make sure that the system is full and at operating temperature, and the heater controls set on full heat. Feel the hoses at the firewall; if they are both too hot to touch then the problem is in the heater box or controls.

There is a heater core valve on vehicles that have a dual zone, ( climate control ) systems. The valve is in the area of the heater core.

Something to try. allow the engine to run for 6 to 8 minutes with the heater wide open, then, turn the engine off and reach back and feel the 2 hoses at the firewall that lead to the heater core. If only 1 is hot you do have some blockage, if both are hot then it is circulating properly and your problem lies somewhere else.

Dual zone systems also have a split door between the heater core and a/c evaporator that often stops functioning properly and it can block the hot air comming from the core.

vw group products used to have a bleed valve on the top heater hose,to vent any trapped air,now you have to undo the jubilee clip on the top heater hose,ALL vw NEED to be bled after refilling water system.

the hot water line from the engine goes through a valve that is controled by the temp control on your dash,older ones were cable control, the newer ones are usually vacuum controled,look for a vacuum leak at valve or dash control

Look for a heater control valve under the hood connected to one of the heater hoses and make sure the valve is operating properly. This is what allows the hot water to pass through your heater core. Also your heater core may have a blockage.

Heater core is plugged or you have a air pocket. If you take off the heater lines and try blowing through them both ways. The fans will not move until the engine gets hot.

Have you checked the heater core hoses? If they are not "hot" the heater core needs to be replaced

there is a water control valve near the firewall where the heater hoses go in to the heater core. Make sure your hoses feel hot when engine is fully warmed up.. one should be hot and the other cooler as it is your return. the water control valve might be faulty not letting water enough get into the core. thanks jerry holler if you need more..

This sounds like one of two things, either there is not enough coolant in the system, or the heater control system is messed up. try this, with your car running at about 205 degrees (feel the upper radiator hose, it should be hot to the touch) grab both of the hoses going into the heater core behind the engine, the should be warm to hot. if they're not warm at all, or just luke warm, you either don't have enough coolant, or the hoses are blocked somewhere. if there is a valve in line with one of the hoses, try to operate it by hand, sometimes those valves (called heater valves) fail.

if the coolant is full and there is hot coolant in both hoses going into the heater core, then you're controls inside are likely the problem. try to turn the heat control from cold to hot and back again a few times, you should be able to hear a clapping sound,it might be very faint, so listen carefully. if you can't hear anything, it's likely the controls itself, unless you hear a hissing sound from behind the dash when you turn the control, that would be a vaccuum line unhooked. you'll have to pull some panels under the dash to find this vaccuum line to hook it up, but it's not too hard , just takes patience. (it's more common for a heater control to go first)