Try gently tapping in.
It is best to just replace it.
Its cheap and ez to do
check the thermostat
Yes or possibly a stuck thermostat. this is most likely a stuck thermostat. Heater uses water coming through hoses to heat the air. If the thermostat is stuck, the water in the hoses does not get hot. it also explains why you're overheating. be sure to top off coolant after you fix the problem.
You should gas mileage will suffer otherwise
change the thermostat
In order to fix a stuck thermostat in a 1994 Ford truck, one should take the truck to a certified Ford mechanic to complete the work.
The engines thermostat is probably stuck open or has been removed, so change the thermostat and this should fix your problem.
From your description it sounds as if the cooling system thermostat needs to be replaced. Sounds like it may be stuck in the open position which doesn't allow the coolant to warm up sufficiently to supply heat to the radiator.
Possible cause thermostat bad stuck open
Your thermostat is stuck in the open position. Replace the thermostat and no more problems. Quick fix and only costs about 20 dollars.
If your main gas valve is stuck in the closed position, it must be replaced. This condition is the reason your thermostat will not cause the main burners to light.
First check the coolant level, a coolant leak would cause a heater to stop working- assuming you mean the blower is blowing but it isn't hot. A stuck thermostat will also cause you problems with your heat.
sounds like your thermostat wires are touching somewhere.. maybe a nail was hammered into it or possibly something chewed on it..