Hi,I just acquired my father in law's 87 B2200 P/U 5 speed no anything 72K. I fixed oil leak Tuned up & finially passed NJ Inspection.
Now I just realized I have no heat @ all. Do Have hoses going to heater core. Temp gauge moves very little almost 1/4 way but no sign of heat. Radiator full. Next step is to change thermostat I guess. Does the cold hot **** have a tendency to malfunction? Any suggestions would be greatly appreciated. TY Randy

 

Yes the temperature module breaks quite frequently in these trucks, you can manually set the temp by a lever located on driver side next to the gas pedal, it should have a cable attached just move the lever up/down to your desired temperature.

 

is it the same on a 90 b2600i

 

I have 98 Milly, also had no heat. I had to have the actuator motor replaced.For my car it was part number TAO-61-A60. It was an expensive little motor! List price of $213.00! It is the acuator that closes off the cold and allows heat to come through! They had to remove the dash cover, etc. I hope this helps.

 

Is it the same for the 86 as well as i have no heat.

 

If the hoses to the heater core at the firewall get hot (after maybe 10 minutes), then the problem is in the dashboard controls. The 86-93 B Series has the hot coolant running through the heater core at all times. The cold/hot **** controlsa flap or "door" directs the air flow around the heater core, and this is controled by a cable. Get a helper toturn the **** and look up under the dashboard, both sides, to see if you can see the cable moving, and make sure it's attached. Also move the lever from Vent to Heat and make sure that cable is also moving and attached, that directs the air flow to right at you to down at feet for "heat", and to windshield in "defrost". I've had one of my cables come off, and had to reconnect it.