I’ve got an ‘88 Dakota V6, no ac, and was wondering if anyone would have any insight as to why I’m not getting much heat out of the vents. Both of the lines running to the core are hot to the touch, the engine is up to temperature, but very little heat comes out of the vents. I’ve taken the core out and flushed it both ways to make sure nothing was stuck, and it’s had the thermostat replaced within the last couple years. I haven’t had heat since I got the truck. The heat slider is always on full heat and no matter what vent you tell it to come out, it’s always just warm. When driving, the temp coming out of the vents gets even colder. Was wondering if having the lines to the heater core crossed could cause this or what you guys would recommend for me to look at. I just put a new transfer case in yesterday and I wanna be warm when I drive to work. Thanks

 

Does the blower fan work?

 

If I remember my Ralph reading correctly the doors that direct airflow are controlled by vacuum lines. Check to see if yours are leaking.

Edit here's a couple videos that may help

 

Yes, the blower fan does work. It works on all the different speeds as well.

The doors do change when I move the slider. Just no heat comes out of any of the vents that I choose.

 

Clogged heater core, low on coolant, screwed up blend door.... etc.

 

OK I have another truck, also never had heat since I bought it. I flushed it, changed the entire heater for another one. New water pump new hoses that also did get hot. Nothing.Found out the valve that opens when you turn move the lever to heat was not working replaced it also nothing. Then about 3 or 4 years ago I flushed the whole motor before I put in a new aluminum radiator I was adding to cure the dam plastic tanks that kept leaking and an overheat issue. I used all distilled water and in one gallon I poured out enough to add one 1lb box of dry TSP. You get it at the Home Despot paint department. I ran it until hot, got all the bubbles out kept filling it etc. Let it cool down and ran it til hot again about 3 or 4 times over a couple three of days. I even drove it a bit. Then I drained it and flushed it with distilled water. Lot of tedious work. Now I have heat from my heater. ??? I guess something was clogged that the TSP cleared up. It still wants to overheat in summer on some days. That or you have something like a mouse nest blocking the duct work but I think you'd smell that.