Hey I'm new here, but have been knee-deep in my work van. Since I started driving it I've had no heat. I replaced the tstat and the coolant temp switch last week. I check the coolant level every day and all the hoses for heat, both the radiator and heater core hoses. Checked heater core and all linkages back to the dash controls. I'm stuck!!!

The other issue is the temp gauge on the dash. It doesn't move from C, no matter how long or how far it's driven.

 

It sounds like you have one of the following three issues. (1) Your heater core may be clogged. There was some very recent discussion about back-washing the heater core to resolve this issue. (2) The valve that controls coolant flow into the heater core may be seized in the closed position, or the vacuum line that controls the valve may have an issue causing the valve to remain closed. I think the '94 uses vacuum to control that valve but it may indeed be a manual cable -- anyone? You should be able to tell just by looking at the valve where it attaches to the heater core coolant inlet hose. (3) The blend door in the HVAC housing is also controlled by vacuum. Sometimes when you have no heat it is because the blend door is in the wrong position and therefore not directing warm air to the floor as it should. Again, vacuum gremlins.

The Temp Gauge is probably a seperate issue either caused by a faulty sending unit or a bad gauge in your cluster. I have a replacement cluster you can have for cheap if you want -- let me know via this thread or PM me.

 

94 uses a cable to control the tempature blend door.
But it does have the vacuum operated shut off valve between the top of the engine to the left of the top radiator hose and the heater core.

Does your temp selector on your HVAC panel have resistants when you move it? If not check to be sure the cable is connected to the blend door under the hood. It is on fire wall right where the right side of the HVAC box stops under the hood.

 

Found out I had little pressure on the cooling system so I replaced the pump yesterday. Unfortunately I still have no heat and I think the next step is to clean out the core support box and ill check the core.

 

Hey rusty93, is that sending unit you mentioned located behind the alternator to the left of the tstat housing and screwed into the coolant resivour

 

Yes it is, and it's a bitch to get to unless you remove the alternator from what I recall.