My heater is not working?

Tiny
CJ04
  • MEMBER
  • 2002 DODGE RAM
  • 4.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 2,000,000 MILES
Minimal heat on all settings when driving little to no heat when idling.
Do you
have the same problem?
Yes
No
Friday, October 30th, 2020 AT 5:42 AM

16 Replies

Tiny
ASEMASTER6371
  • EXPERT
Good morning,

Make sure the coolant level is correct.

https://www.2carpros.com/articles/radiator-pressure-test

https://www.2carpros.com/articles/car-heater-not-working

The thermostat could be stuck open not allowing the engine to heat up and give good heat.

https://www.2carpros.com/articles/replace-thermostat

The heater core could be clogged. I would disconnect the hoses at the firewall and use a garden hose to clean out the dirt and debris in the core. Run the water both ways until the flow is clear and clean.

The heater core itself. I attached a YouTube video of this procedure.

https://www.youtube.com/watch?v=_9oxC8IWz_E

https://www.2carpros.com/articles/replace-heater-core

The blend door actuator. I doubt it is that as you have heat off idle. If it was the actuator, it would be the same all the time.

https://www.2carpros.com/articles/replace-blend-door-motor

Roy

REMOVAL
The single zone heating and air conditioning system is equipped with a single blend door actuator. The dual zone system has two blend door actuators, one for the driver side blend air door and one for the passenger side blend air door. The same service procedures can be used for each of these actuators.

WARNING: On vehicles equipped with airbags, disable the airbag system before attempting any steering wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the airbag system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the airbag system. Failure to take the proper precautions could result in accidental airbag deployment and possible personal injury.

1. Disconnect and isolate the battery negative cable.
2. Remove the instrument panel assembly.

Fig. 14 HVAC Housing - Dual Zone Shown (Typical - Single Zone)
imageOpen In New TabZoom/Print

3. Disconnect the HVAC wire harness connector for the blend door actuator from the actuator connector receptacle..
4. Remove the screws that secure the blend door actuator to the distribution housing.
5. Remove the blend door actuator from the distribution housing.

INSTALLATION
1. Position the blend door actuator into the heater/air conditioner housing. If necessary rotate the actuator slightly to align the splines on the actuator output shaft with those in the blend air door linkage.
2. Install and tighten the three screws that secure the blend door actuator to the distribution housing. Tighten the screws to 2 Nm (17 in. lbs.).
3. Reconnect the HVAC wire harness connector for the blend door actuator to the actuator connector receptacle.
4. Install the instrument panel assembly.
5. Reconnect the battery negative cable.
6. Perform the heater-A/C control calibration procedure.

Thermostat

THERMOSTAT

REMOVAL

WARNING: Do not loosen the radiator draincock with the cooling system hot and pressurized. Serious burns from the coolant can occur.

Do not waste reusable coolant. If the solution is clean, drain the coolant into a clean container for reuse. If the thermostat is being replaced, be sure that the replacement is the specified thermostat for the vehicle model and engine type.
1. Disconnect the negative battery cable.
2. Drain the cooling system.
3. Raise and support the vehicle.
4. Remove the splash shield.
5. Remove the lower radiator hose clamp and the lower radiator hose at the thermostat housing.

imageOpen In New TabZoom/Print

6. Remove the thermostat housing mounting bolts, thermostat housing and thermostat.

INSTALLATION
1. Clean the mating areas of the timing chain cover and the thermostat housing.
2. Install the thermostat (spring side down) into the recessed machined groove on the timing chain cover.
3. Position the thermostat housing on the timing chain cover.
4. Install the housing-to-timing chain cover bolts. Tighten the bolts to 13 Nm (112 inch lbs.).

CAUTION: The housing must be tightened evenly and the thermostat must be centered into the recessed groove in the timing chain cover. If not, it may result in a cracked housing, damaged timing chain cover threads or coolant leaks.

5. Install the lower radiator hose on the thermostat housing.
6. Install the splash shield.
7. Lower the vehicle.
8. Fill the cooling system.
9. Connect negative battery cable.
10. Start and warm the engine. Check for leaks.
Was this
answer
helpful?
Yes
No
Friday, October 30th, 2020 AT 6:01 AM
Tiny
MATTWRIGHT
  • MEMBER
  • 2002 DODGE RAM
  • V8
  • 2WD
  • AUTOMATIC
  • 115,000 MILES
My heater has not been working and recently the truck overheated. My mechanic replaced the fuel pump, which did not solve the problem. Then the thermostat was replaced which helped but the truck still seems to be overheating, I have not taken it on a long drive yet as I work fairly close to home, and my heater still does not work. What could possibly be the problem?
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
BMRFIXIT
  • EXPERT
1st they changed the water pump and not fuel pump (I hope to solve over heating problem )
is it loosing coolant
check head gasket
flush coolant system and heater core
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
TJSPRING1
  • MEMBER
  • 2002 DODGE RAM
  • V8
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
The heat only comes out luke warm on low speed but goes to cool on any higher speed and never does get hot I have changed tstat but made no difference
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
PEAR69
  • MEMBER
Your heater core may be blocked or (if you engine has this valve) the heater core coolant valve may be bad. To find this valve follow the heater core hoses -- you'll find it.
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
LILJJ1650
  • MEMBER
  • 2002 DODGE RAM
  • V8
  • 4WD
  • MANUAL
  • 66,589 MILES
My 2002 dodge ram 1500 heater blows out cold air unless the engine is reved up or the truck is moving other than that it blows out cold air when it is idiling
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
HIGHROLLER
  • MEMBER
I have a 2000 Ram with about the same miles and I am having the exact same issue. I check the coolant level and the radiator cap is brand new. I was going to replace the thermostat.
Hopefully that works. It's -40 and COOOOOLLLDDDDD.
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
BMRFIXIT
  • EXPERT
Check WATER PUMP
Check coolant level

most cases its the heater core

Check heater core hoses if both are hot, if not the heater core need to be flushed as a 1st step
these are the steps
WARNING: NEVER REMOVE THE PRESSURE RELIEF CAP UNDER ANY CONDITIONS WHILE THE ENGINE IS OPERATING. FAILURE TO FOLLOW THESE INSTRUCTIONS COULD RESULT IN DAMAGE TO THE COOLING SYSTEM OR ENGINE AND/OR PERSONAL INJURY. TO AVOID HAVING SCALDING HOT COOLANT OR STEAM BLOW OUT OF THE COOLING SYSTEM OR DEGAS BOTTLE, USE EXTREME CARE WHEN REMOVING THE PRESSURE RELIEF CAP FROM A HOT COOLING SYSTEM OR DEGAS BOTTLE. WAIT UNTIL THE ENGINE HAS COOLED, THEN WRAP A THICK CLOTH AROUND THE PRESSURE RELIEF CAP AND TURN IT SLOWLY UNTIL PRESSURE BEGINS TO RELEASE. STEP BACK WHILE THE PRESSURE IS RELEASED FROM THE COOLING SYSTEM. WHEN CERTAIN ALL PRESSURE HAS BEEN RELEASED, PRESS DOWN ON THE PRESSURE CAP (STILL WITH A CLOTH), TURN AND REMOVE PRESSURE RELIEF CAP.
Engine cool
lower the coolant level
Locate the two hoses running to the heater core
disconnect them at the engine side leaving hoses connected to heater core throw the firewall
use garden water hose and compressed air if possible
run the water and follow by air throw one side and out the other and vice versa
do that two to three times watching what leaving the heater core you are looking for the good flow and clear water to run throw
reconnect hoses
top off coolant system
good luck
let me know
Was this
answer
helpful?
Yes
No
+1
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
MICHAEL1128
  • MEMBER
  • 2002 DODGE RAM
  • 87,000 MILES
Do you guys have a link where I can see how my heat lines go on my 2002 dodge ram because I think I mixed mine up and now I cant get no heat in the truck?
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
You really can't mix them up. If you switched them on the heater core, it will still work. Are both heater core hoses getting hot?
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
MICHAEL1128
  • MEMBER
Yes the both get warm but inside the cab it doesnt heat above room temp.
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
If they both get hot, that tells me the heater core is flowing. Thus, you should have heat. If you don't, chances are the blend air door isn't operating. It is near the heater core and opens and closes based on if you want heat or AC.
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
RAM GUY1
  • MEMBER
  • 2002 DODGE RAM
2002 Dodge Ram V8

i have a 2002 ram 1500, I have disconnected the heater lines to the firewall and have flushed the heater core till it ran freely and clear water. But I only have heat coming out the passenger side air vents, cool air comes out the drivers side?Also I have a hint of ant freeze smell outside the truck after it runs for a while but no one can find a leak?
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
The interior problem is most likely a result of a bad vacuum hose. The vents are actuated by engine vacuum. Chances are one of the vacuum hoses under the dash is either broken, disconnected, or cracked. As a result, the vent isn't allowing heat to make it to its destination.

Check for leaks. With the engine running, you may hear a hissing sound.

Let me know what you find.
Was this
answer
helpful?
Yes
No
-1
Friday, November 27th, 2020 AT 11:04 AM (Merged)
Tiny
BIGFOOTBEEKER
  • MEMBER
  • 2002 DODGE RAM
  • V8
  • 4WD
  • AUTOMATIC
  • 131,000 MILES
My heater started blowing cold air so I replaced the thermostat. This did not work so I flushed the heater core and the problem was resolved for 1 day then it reverted back to blowing cold air. Any suggestion on where else to look?
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:05 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi:
If you flushed the heater core and it worked for a day, it makes me believe there is something in the engine or the radiator that is causing it to plug up.

Try having the engine and radiator flushed (and the heater core again too).

Let me know if this helps.

Joe
Was this
answer
helpful?
Yes
No
Friday, November 27th, 2020 AT 11:05 AM (Merged)

Please login or register to post a reply.

Sponsored links