We have a '92 F-150 XLT. We Have Replaced the Thermostat and Water Pump, and still have no heat. We are told that we have to replace the heater control valve, but do not where it is located.
Get under the hood and trace the 2 heater hoses towards the firewall. One of these hoses will be connected to the heater control valve. I suspect that it’s in the “off” position. To test the system just remove the heater valve and replace it with a bypass tube. You should have heat as soon as the engine warms up. If this works then replace the heater control valve.
from near the water pump, you should have two hoses (5/8") going to the firewall on the passenger side. Check if with the engine warm both hoses are hot. The heater control valve is located on one of those hoses near the havac box. If you see a small hose attached to it check for vacuum there.
We are told that we have to replace the heater control valve, but do not where it is located.
Who told you that? Why? Did they do the work to make sure that is the problem?
It could be just a blend door stuck due to a loose vacuum hose somewhere.