Pressure is not a good indicator of water pump operation. Pressure in the cooling system comes from the heating of the water and its expansion. Jettas come from the factory with plastic impellers on their water pumps. These have a tendency to break and fail, causing overheating issues. Most aftermarket pumps have metal impellers to prevent this from happening. I would seriously consider having the water pump replaced, especially if it is original and you have more than say 60K miles on the car. It's due for a change anyway and may save you your engine. See what this guy had to say about his Jetta.....
Engine Overheating Due to Damaged Water Pump Impeller Volkswagen Jetta...
SOURCE: Cool air blowing from heater, even when on high.
if the heater core is bad, it will leak or not flow water. even tho you can "hear" the blend door working, it may not be actually moving inside the box. check to see if the actuator is connectd to the blend air door. You may be hearing the actuator moving but not the door.
SOURCE: no hot air from heater, blower runs fine
The heater in your car depends upon a flow of hot coolant going through the heater core in order to get hot air into the car. If the heater core is partially plugged, it will restrict the flow. If you have a head gasket that is putting exhaust into the cooling system, it will eventually get into the heater core. When this happens there is no coolant in the heater core to make the air warm. If the water pump vanes have corroded away the result will be very poor coolant circulation causing the heater to not blow hot air. If your car is equipped with a heater control valve that is not functioning properly, the coolant flow will be restricted. One or a combination of these factors is likely the culprit in your case.
Since you state the 2 things you ruled out, that leaves only the water pump. Is the car running hot? The thermostat may be sticking as well... but im leaning toward the pump.
SOURCE: OVER HEATING
In the fan circuit...You have a temp switch screwed on the radiator, a fuze and a relay in the fuze box plus a fan. Swap the relay with another relay, replace the fuze. The other fan should come on when the a/c is turned on. If you fix the fans and it still overheats, you may have a BLOWN HEAD GASKET. ALSO ARE YOU BLEEDING THE AIR FROM THE SYSTEM? DO YOU SMELL EXHAUST IN THE COOLANT?
SOURCE: 2002 subaru legacy heater not working
heater core could be plugged,try removing both heater hoses to core and back flush
SOURCE: car overheating, blows cold air out vents, changed
A couple of things to check because as you describe your symptoms you actually have 2 problems
1. No heat from vents.
Sounds like the heater water flow valve cable is kinked disconnected or the valve itself is stuck You will need to follow your heater core water supply lines to find the valve usually to the right of the center console in the ducting area / large plastic housing for heater and AC internal coils. If the valve works then there is a possibility that the heater core water supply lines have been bypassed on the engine side of the firewall with a coupling due to a leaking heater core. And l;astly the heater core could just be clogged. (quite rare!!)
As for the overheating engine after all of the work you have done.. Perform this simple test.
1. remove radiator cap
2. have someone else start the car
3. watch for water coming out of the open radiator cap area DURING start...
4. have person in the car rev engine gently 2 or 3 times. No need to exceed 2000 RPM. If water rapidly flows out of the radiator during engine revs.. you have some major engine issues.
If it passes all of these checks then the only thing left is improper hose connections on the engine side of the firewall and or a hydraulic water lock in the block that should clear itself by starting and stopping the engine many times with the radiator cap off.
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