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are there any dodge truck techs here?


oldrusty
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Anybody out there a dodge truck tech? My brother has a 2001 ram with a 5.9 that isnt making heat. Hes already thrown about 400$ worth of parts at it now he wants me to work on it. If anybody knows anything about these pm me and I'll give you the details.(don't want to waste valuable space with non comanche propaganda...lol)

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You can take up as much space as you need asking any tech question you'd like. :thumbsup: The only rule is that it doesn't go in the MJ tech forum. The Pub is fair game. :cheers:

 

So you mean the engine isn't warming up? Or that there's no heat coming from the dash vents?

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he had all these parts replaced today at one time. He says its making more heat now than before but still isnt making heat like it used to. I looked at it yesterday evening and according to my digital thermometer the upper rad hose and both heater hoses were 190 degrees but the lower one was only 70 degrees. This evening he stopped by on his way home (about a 40 mile drive) and the radiator cap was cool to the touch. Almost seems like the cooling system is working to good.

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I am not a Dodge tech but I am ASE certified in A/C. The heater blend door on those trucks is controlled by an electic actuator, If the heater case has been apart for any reason (heater core or evaporator replacement) it will need to have its position recalibrated altho I don't have access to the manuals I am sure an internet search will find it.I ran into the same problem a few years ago after an evap job. The actuator is hard to get to as I remember its on the bottom of the evap case. Good Luck

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Heater case has never been apart since my brother has had the truck. Would the blend door allow outside air mix with the heater air? Or does it just control where the air comes out...ie ...dash vents, defrost,ect?

 

 

A 'blend door' blends ambient (outside) air with air that has passed through the heater core (or evaporator core). If it is stuck open, it will be cold. No way around it.

 

If you get 190* on the rad hose and heater hoses, that is okay. If you get 70* on the lower rad hose, also okay. My reasoning is, with a 195* stat that is accurate to a couple percentages, and given rubber is a decent insulator, 190* should be fine for the hot side. Since the lower (cold) hose is quite cold in comparison with the upper (70*, of course I have no idea what your ambient temp is), this is also a good sign as it means not TOO much coolant is passing through the rad or you would see a much smaller spread between the temps. Also, 190* on the heater core hoses verifys that the heater core is hot.

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he had all these parts replaced today at one time. He says its making more heat now than before but still isnt making heat like it used to. I looked at it yesterday evening and according to my digital thermometer the upper rad hose and both heater hoses were 190 degrees but the lower one was only 70 degrees. This evening he stopped by on his way home (about a 40 mile drive) and the radiator cap was cool to the touch. Almost seems like the cooling system is working to good.

 

 

If BOTH heater hoses were the same temp that is a clue. If you had the heater on full hot with the blower on high, then the outlet should be quite a bit cooler as the heat is being carried from the heater core to the air passing through it. If the blend door actuator is faulty and it is stuck on cold, then the blend door is stopping the air from passing through the heater core and the air is just going through the evap coil. It may also be that the blend door itself is broken. Either way the dash, and maybe the box, need to come out. Piece of cake on that truck.

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Thanks forth clarification on how the blend door operates. I guess Ill have to look into it. I forgot to mention that my first thought was that the thermostat was bad. We replaced it last weekend before any of this was done. It was also changed out yesterday and replaced with a mopar tstat when he let the ford techs loose on it.

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D AND TESTING - HEATER PERFORMANCE

Before performing the following tests, refer to Cooling 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. Also be certain that the accessory vacuum supply line is connected at the engine vacuum source.

 

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 knob in the full hot position, the mode control switch knob in the floor position, and the blower motor switch knob 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 62.2° C(144° F) 63.8° C(147° F) 65.5° C(150° F) 67.2° C(153° 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.

 

An alternate method of checking heater performance is to use a DRBIII® scan tool to monitor the engine coolant temperature. The floor outlet air temperature reading should be no more than 4.5° C (40° F) lower than the engine coolant temperature reading.

 

 

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:

 

An obstructed cowl air intake.

Obstructed heater system outlets.

A faulty, obstructed or improperly installed blend door.

A faulty blower system.

A faulty a/c heater control.

TEMPERATURE CONTROL

If the heater outlet air temperature cannot be adjusted with the temperature control knob on the a/c heater control panel, the following could require service:

 

A faulty a/c heater control.

A faulty blend door actuator.

A faulty, obstructed or improperly installed blend door.

An obstructed cowl air intake.

The engine cooling system.

Heater Diagnosis

CONDITION POSSIBLE CAUSE CORRECTION

INSUFFICIENT HEATER OUTPUT. 1. Incorrect engine coolant level. 1. Check the engine coolant level. Refer to Cooling for the procedures.

2. Air trapped in engine cooling system. 2. Check the operation of the coolant reserve/recovery system. Refer to Cooling for the procedures.

3. Incorrect engine coolant temperature. 3. 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), air flow (missing or improperly installed radiator air seals or fan shroud). Refer to Cooling for the procedures.

4. Blend door actuator inoperative or defective. 4. (Refer to Controls/Blend Door Actuator) in this group.

5. Blend door not operating properly. 5. Check for a damaged, obstructed or improperly installed blend door or seals. (Refer to Controls/Blend Door Actuator) in this group.

6. Insufficient air flow through heater housing. 6. Remove foreign material or obstructions from cowl air intake.

7. Improper blower motor operation. 7. (Refer to Distribution/Blower Motor/ Diagnosis and Testing) in this group.

 

This is from the 2001 FSM for heater performance testing.

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