My 1998 Dakota has no heat; the hot water hoses into and out of the heater core are hot. The mode doors work and direct air to the dash vents, defroster and floor. Problem is that the air is outside temp even when the engine is at normal operating temp. Does anyone know if the blend door is vacuum operated, cable operated or electrically operated. Also, do you know how to get to the blen door if it can be operated manually. Lastly, would a stuck hot water shut off valve cause this (I have hot water both in and out of the heater core so this may be unlikely) thanks in advance.
Anonymous2007-03-07T17:58:58Z
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I recently had the same situation with a 97 Dakota. I changed the thermostat, but it didn't make any difference. I fixed my problem by disconnecting both heater hoses (one near the thermostat, one near the water pump) and flushing the heater core with a garden hose. Now I have heat again! (p.s. the blend air door is cable operated)
If both your heater hoses are hot and the rad upper hose stays cold until approx 10 minutes after you do a cold start its not the Thermostat. If the Tstat failed open the heater hoses would never get "hot" and you would get some heat to the cabin and the upper rad hose would start heating up very soon after start up and at the same rate as the heater hoses.
I had this problem on an 88 mustang once - The mustang control head for the HVAC system was broke - the temperature dial stayed at full cold even after cranking it to hot. Not sure of the 98 dakota but it is likely a cable operated door - the HVAC control temperature dial is connected to the temp door in the HVAC module by a cable. - Try this - turn the ignition on, Blower off, engine off and turn the temperature selector - you should be able to hear the door move in the module under the Instrument panel - if not the HVAC controls are not moving the temp door and its likely stuck at full cold. It may be just a bad connection at the controls, a broken cable (or wire)or a stuck temperature door in the module.
There is no hot water shut off valve, this isnt a furnace in your house. Sounds like your thermostat is gone, hence why you have no heat. Also could be your heater core (domestics have this problem more than imports), thermostat is around $10 so change that first, heater core....well lets hope it doesnt go that far.
Replace the thermostat. The thermostat is essential for proper heater operation. Check your trucks computer for a code that states engine temperature too low for too long. Hope this helps, Jess.