So as a continuation of my '92 Build, I've noticed that the heater was actually worse (I never thought this possible) than a 3rd Gen Taurus...

With the nights FINALLY getting cooler and humidity making it seem like the Tropics, heat is a very nice thing to have at 4:30 in the AM. However, I've noticed that in the past couple weeks the output has gone from mediocre to none. I've replaced the heater core since the old one looked like something off the Titanic, changed the fluid, and even gone to the point of running a 3600psi water jet through the system. Yet for some reason it's worse than mediocre but better than nothing. Every last hose to do with the heating/cooling system has also been replaced. Other than the body, I almost have a new truck...

Did Dodge do a bad and design a crappy heating system?

 

Nope. Most first gen Dakotas will burn you out of the cab.

Just throwing out the basics:

Was the system burped properly?

How's the thermostat and what temp is it?

What's the temp gauge say going down the road?

Heater core seams to be ruled out. Positive the lines aren't swapped topped to bottom?

What fluid is in the radiator? Full strength, 50/50 or pure water?

That's all I've got for now.

 

As Toby said, heaters on these trucks work great!! Dont know the difference between the 87 and the 92, but the 87 has a valve to control water flow. I would start with, is the heat guage coming up to normal? Then with the heater on and running for a few moments, are both heater hoses getting hot? Feeling with the hand, there should be very little difference in them. If there is, it sounds like a flow problem, Which is likely the valve.

 

I'm not sure if before, but I know once the magnums were introduced, no more valve.

 

FWIW Rockauto shows a valve through 93 for a v6 dakota. Likely a misprint though.......
But as you stated earlier, check to see that the engine is getting up to operating temperature as well as all the other common sense things, ie. full of coolant, etc.
Then I would feel the hoses going in and out of the heater core. If they are both hot, flow is not your problem.
If there is no water valve in the system as Toby said, I would assume there is a door of some sorts to direct air either over the evap, or over the heater core.

 

Coolant is Mopar 75/25 mix, EVERY pipe, hose and sensor to do with the coolant system was replaced when the new engine was put in. (Went from a 2.5 to a '99 3.9) I know air is getting through no issue with all vent selections, the thermostat is a 175* Murray. My only guess is there's something to do with the Bi-Level setting or A/C system that's still engaged. I've noticed that it doesn't push the humidity as it would if it was just normal heat, so the clutch in the pump might be catching. No different than a elec. blade engage on a garden tractor.

 

Why are you running such a low * t stat? Put it back to stock 195* then get back with us of the problem persists. (Remember, that's YOUR own advice) lowest a magnum "should" have in it is 180* and even then some people report problems.

 

Toby's right about that thermostat.

You've intentionally set it lower than stock, way lower than it should be for proper engine operation, and are complaining it's not getting hot enough.

I'll add that at 195*, my LA 3.9 will curl the toes of your shoes in short order, and that's with the Extreme Cooling option on my truck (retrofitted; it do get warmish in Louisiana in August.)

RwP

 

I had a 210* Thermo in it and still wasn't working. Only reason I keep it so cool is I'm towing 25-36ft Tag-a-longs behind it for 600 miles at a time. Most of the routes are steep grades and even then it starts to touch 230 at times. I'll try cleaning out the system again and put that other Thermo back in.

Question: How similar are the '01 and 1st Gen HVAC systems? I know the '01 will dry a sopping mop in less than 10 mins.

 

I don't know, but my truck is 1988 - second year of production period, definitely first gen.

It has great heat in the winter, always has, even with the Extreme Cooling radiator (note: the Mopar package was called Extreme Cooling; that's not a brand.)

I'd say it's fair time to triple check the water flow through the heater core; everyone that complains about no heat turns up to have a plugged heater core. This is also true of my 1991 Cougar and the other MN12, my old 2000 Maliby, my ancient 1967 Mustang, etc.

RwP