No heat 85 300dt.. I searched...where to start
 

I searched a bit and found some related info.
Posting for a friend with heater woes....

85 300d turbo and I get no heat ... motor is up to temp and the AC works fine.
I am still a little puzzled by the icons on controls on the console but they work.... I am used to the 240 on -off knob.
Thermostat seems to be good and it does not over heat.
Is the heater electrical contrlled or vacuum or both

opinions and links appreciated..

bennett

1. Check the monovalve. It could be stuck closed, or some one wired it to recieve a constant 12 volts. The monovalve is supposed to open, allowing hot water to flow, at 0 volts.

2. Also check to make sure the heater core was not bypassed.

Core was not Bypassed... he had heat up until a few weeks ago.
The fan blower works and blows good air.. just no heat
fuses are good... did burn one a few weeks ago when the hood pad fell off under the hood and laid on the motor and she got warm but not overheated.

Where is the monovalve?

Check to see if the monovalve is getting juice or not. In the heat setting it gets 0 volts, and it's supposed to open. It is mounted on the firewall, passenger side near the valve cover.