I have a 1988 B150 van that's been parked on a wooded property for almost 2 years. I recently cleaned it up, changed fluids, got her running smooth but aside from the speedometer problem that Landyacht has graciously helped me with (thank you so mch), I now realize that the heat is not coming on. The blower motor is working fine, just no heat (or AC for that matter). Any suggestions on what may be the problem? My father who parked the van 2 years ago said that when he parked it, the heater was fine.

 

Are both heater hoses going to the heater core hot?

 

Both upper and lower hoses are hot coming out of the radiator after vehicle warms up for 10 minutes or so.

 

What about the two going to the heater core?

 

Forgive me but I'm a rookie. Where is the heater core and those hoses?

 

There's a large black box under the hood on the passenger side, that's the heater/AC box. The blower motor is mounted in the engine side, bottom of it. At the top rear of it against the firewall is two hoses about 1" in diameter running to this heater box. Those are your two heater hoses and they run to the heater core (looks like a mini radiator) inside the heater box. The hot coolant from the engine circulates through these hose and the heater core, making it hot. Air from the blower motor is pushed through the heater core causing the air to heat up as it passes through and out into the cabin area. That's the basics of how heat works in a vehicle.

Now, if both of the hoses aren't hot, then coolant isn't circulating through the heater core, leaving it cold. If the heater core is cold, then so will be the air after passing through it.

 

Thank you so much. Therefore, if the hoses aren't hot, am I to assume that the heater core is bad or is it something PRIOR to the core that's bad?

 

It could mean the heater core is plugged up, preventing flow. There is also a heater valve in-line with one of the hoses that closes to stop the flow only when using the A/C. I've seen those valves get gunked up inside and prevent flow as well. But first check to see if both hoses get hot and then we'll take it from there.

 

OK, after 10 minutes of running the motor, both hoses are hot. I should say the top one is hot and the bottom one is warm. I turned on the heat and it was fine for a minute. I then turned it off and turned it back on and and it blew cold air. It seems to be an intermittent problem.

 

Okay back to the heater box. On top of the heater box is a linkage rod that comes off a lever and runs through the firewall. This is the lever for the blend door. The blend door is what flips between heated and unheated air to give you cold, hot, or warm air out of the vents. See if this linkage moves as you move the dash temperature **** from hot to cold and back again.