I have a 2002 dakota 4x4 with a/c ..having issue with hvac control or mode actuators ... When i have heat set on full heat only place i can get good heat is out of defroster vents ...no matter which position i put it in there is little air flow ...i took dash apart so i could see actuators and the doors seem to be working properly ... When i move the heat control to full cold temp i have full air movement in all position ...when i put it back on hot temp heat i loose the force air from blower but blower is still working in all positions this is very strange ..it will cook you out of truck with defroster ...

 

Welcome to DF

I will move your post to the 2nd gen Dakota section. The defroster is the default mode.

 

Thank you ...do i need to replace the control or what is the fix for this

 

????why is it then when it is set to cold all the position have thew same air flow with no issues... its switching mode poistion just lack of air flow

 

My 2001 does it too, gets more hot air out the defroster than the floor vents. I live in Florida so it really is hardly ever a problem anyway. I found it helps a little if I close all of the dash vents when I do use the heater. I feel more air flow from the floor vents that way.

It also helped the floor vent air flow when I changed out my blower motor a couple years ago. My original blower was drawing too much current and burning up the resistor pack. I put in a new blower motor and a new resistor pack and the air flow from both the floor and dash vents picked up a very good increase. You might also try putting a towel or something over the defrost vents to help force more air out the floor vents.

I have to wonder if Dodge and other manufacturers too did not design the HVAC system that way on purpose, so it directs more air toward the windshield defroster to keep it clear no matter what the weather is, because they are afraid of lawsuits from people who had a wreck on account of they could not see out their fogged-up windshield. My wife's 2003 Honda Accord does the same thing, blows more air out the defrost than the floor vents.

Jimmy

 

DIAGNOSIS AND TESTING - HEATER PERFORMANCE

Before performing the following tests, Cooling System for the procedures to check the engine coolant level and flow, engine coolant reserve/recovery system operation, accessory drive belt condition and tension, radiator air flow and the fan drive operation.

MAXIMUM HEATER OUTPUT

Engine coolant is delivered to the heater core through two heater hoses. With the engine idling at normal operating temperature, set the temperature control **** in the full hot position, the mode control switch **** in the floor position, and the blower motor switch **** in the highest speed position. Using a test thermometer, check the temperature of the air being discharged at the HVAC housing floor outlets. Compare the test thermometer reading to the Temperature Reference Chart.


Temperature Reference

Ambient Air Temperature 15.5° C (60° F) 21.1° C (70° F) 26.6° C (80° F) 32.2° C (90° F)
Minimum Air Temperature at Floor Outlet 52.2° C (126° F) 56.1° C (133° F) 59.4° C (139° F) 62.2° C (144° F)


If the floor outlet air temperature is too low, refer to Cooling to check the engine coolant temperature specifications. Both of the heater hoses should be hot to the touch. The coolant return heater hose should be slightly cooler than the coolant supply heater hose. If the return hose is much cooler than the supply hose, locate and repair the engine coolant flow obstruction in the cooling system. Refer to Cooling for the procedures.

OBSTRUCTED COOLANT FLOW

Possible locations or causes of obstructed coolant flow:
•Faulty water pump.
•Faulty thermostat.
•Pinched or kinked heater hoses.
•Improper heater hose routing.
•Plugged heater hoses or supply and return ports at the cooling system connections.
•A plugged heater core.

If proper coolant flow through the cooling system is verified, and heater outlet air temperature is still low, a mechanical problem may exist.

MECHANICAL PROBLEMS

Possible locations or causes of insufficient heat:
•A faulty blower system.
•A faulty heater-A/C control.
•An obstructed cowl air intake.
•Obstructed heater system outlets.
•A faulty, obstructed or improperly installed blend-air door or actuator.

TEMPERATURE CONTROL

If the heater outlet air temperature cannot be adjusted with the temperature control **** on the a/c heater control panel, the following could require service:
•The a/c heater control.
•A faulty blend door actuator.
•The blend door.
•Improper engine coolant temperature.
•Obstructed cowl air intake.

Heater Diagnosis
CONDITION POSSIBLE CAUSE CORRECTION
INSUFFICIENT HEATER OUTPUT.
1. Incorrect engine coolant level.
Check the engine coolant level.
2. Air trapped in engine cooling system.
3. Incorrect engine coolant temperature.
Check the performance and operation of the engine cooling system including: thermostat, water pump, fan drive, accessory drive belt, coolant flow (plugged radiator or heater core, plugged or kinked coolant hoses).
4. Blend air door actuator not operating properly.
5. Blend-air door not operating properly.
6. Insufficient air flow through heater housing.
7. Improper blower motor operation.

 

well here we go after finishing taking the dash out today i found the issue with my heat problem ...the linkage for the defroster door is missing .. i'm assuming it fell on the floor and some vacuumed it up or threw it out ...problem is i cant purchase separate have to purchase whole top of heater case at $160 bucks to get a 3 dollar part ...guess we try to fab one first ...checked noumerus suppliers no luck anywhere ...

 

Try a boneyard.