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MCPDougs, Dodge Mechanic
Category: Dodge
Satisfied Customers: 25
Experience:  Own several MoPars and run my own shop- specializing in turbos
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My 2001 Dodge Grand Caravan 3.8 heater has stopped being warm/hot.

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My 2001 Dodge Grand Caravan 3.8 heater has stopped being warm/hot. Everything else seems to control, auto or manual settings. Temp gauge for motor indicates normal warm up and water temp. This came on intermittently and now does not heat at all. No leaks of fluid etc anywere.



Have you replaced the thermostat?


Thanks for using justanswer- Doug

Customer: replied 8 years ago.
I have in the past (we have 110K miles on it). I have asked my wife who drives it if the temp gauge seems to act normally...... i.e not climbing to very hot and then dropping when the themo finally opens, or taking forever to hit normal temp. She experienced that before and said that it is not doing that this time. The problem was very spread out before, just every once in a while...sometimes just needing to turn heater off and then back on to get hot air, but now nothing helps.

well your temp gage, after about 7-10 minutes should be hanging out in the middle of the section - if not consider the thermostat change a good chance to do some maintenance. Does the airflow seem adequate thru the vents (warm or not)?


I'll post the thermostat replacement instructions just in case:

3.0L, 3.3L & 3.8L Engines

  1. Disconnect the negative battery cable.
  2. Place a drain pan under the radiator drain and drain the cooling system to just below the thermostat level. Close the drain.
  3. Remove the upper radiator hose from the thermostat housing, then remove the housing.
  4. Remove the thermostat and discard the gasket. Click image to see an enlarged viewThermostat installation detail-3.0L engine Click image to see an enlarged viewThermostat installation detail-3.3L and 3.8L engines

To install:

  1. Clean the housing mating surfaces.
  2. Dip the new gasket in clean water and place it on the water box surface.
  3. Center the thermostat on the gasket, in the water box. Click image to see an enlarged viewRemove the radiator hose from the waterneck by loosening the hose clamp . . . Click image to see an enlarged view. . . then loosen and remove the waterneck housing retaining bolts
  4. Make certain the bolt threads are clean. Threaded bolt holes exposed to coolant are subject to corrosion and should be cleaned with a small wire brush or correct size thread-cutting tap. Install the housing, making sure the thermostat is still in the recess, and tighten the retaining bolts to 105 inch lbs. (12 Nm) for 3.0L engine or to 21 ft. lbs. (28 Nm) for 3.3L and 3.8L engines. Reconnect the upper radiator hose and tighten the hose clamp.
  5. Connect the negative battery cable.
  6. Fill and bleed the engine cooling system with a clean 50/50 mixture of ethylene glycol antifreeze and water. Click image to see an enlarged viewLift the waterneck housing off of the lower intake manifold, then . . . Click image to see an enlarged view. . . remove the thermostat out of its mounting flange
  7. Make sure the radiator is full and start the vehicle. CAUTION Do not remove the radiator cap once the vehicle is warm. Coolant is under pressure and may cause scalding or personal injury.
  8. Run the vehicle until the thermostat opens. Check the coolant level in the overflow tank and fill if necessary.
  9. Pressure test for leaks. Click image to see an enlarged viewMake sure to clean the waterneck before installation
Does it seem to function better or worse if the engine is reved up?
Customer: replied 8 years ago.
Makes no difference. Temp gauge acts normal set heater and no heat ever now.
ok does the air- flow thru the system seem normal heat notwithstanding?
Customer: replied 8 years ago.
Yes it does

Good, gonna have to get a bit more hands on, can you access the heater hoses? if so make sure there both "hot" just to eleminate a restriction in the heater core itself.

Customer: replied 8 years ago.
Where would I access these? Under dash or hood or vehical?

best access would be underhood / undercar- watch for manifolds(hot) belts pulleys ect


Customer: replied 8 years ago.
When I check them for hot what do I do if cold? What do I do if hot? I guess I am asking if there is a possiblility of an electrical problem with a sensor or is this a common problem with my model etc.

I wanted to confirm the basics, yes more than likely with the info I have so far I would be inclined to believe either a blend door control motor issue or the control head is on the way out. -

Customer: replied 8 years ago.
Thanks for sticking with it!! Is there a way to check/test control doors?

well I was just trying to retreive that info to no avail. don't quite get the problem but it is on my end.


let's do this by the seat of the pants

can you hear/ feel the blend door move when manually switching between hot and cold usually there is a slight audiable noise or sometimes you can hear the difference in the sound of the airflow?

Customer: replied 8 years ago.
My system is fully electronic readout with the temp sensor in dash etc and the three climate zones. I have not specifically checked, but when I turn up the driver or passenger temp I have never noticed a noise or sound change. I have with OTHER cars so I know what you mean, but never with this van.
I'm still leaning toward a blend door servo motor- but I'm having problems pulling anything up to send to you. please excuse the delay, I'll try to secure the info at work and get it out to you this evening. - doug

did find this of intrest:


I was going in this direction, but my info is still messed up- doug

did you get a chance to use the diagnostic? was wondering what code it turned up? will check back later - doug

Customer: replied 8 years ago.
I was able to do two things: I used the turning the key on and off 3-4 times and got the mileage readout to say "done"--- so no engine code to speak of.(Read about that trick somewhere)   

On the heater I found that the holding of the power switch and the recirc button got the recirc symbol and the word "delay" to flash alternately. You could tell that the heater was going through a calibration/check and then they stopped flashing. If I am reading what you sent me correctly then there is no code thrown. I can hear the air flow changing as it checks itself, but the air is still cold. Just tonight my wife was driving home and she turned the heater on and off every few minutes checking to see if it would blow warm air and she actually got hot air flowing and it worked for the last half of the drive home. It hasn't worked like that in over a week. So I think if there is a door/flap that controls the hot air blending that may be the culprit. Let me know what you think!

To be honest, sticking with blend door motor - unless the door is bound or warped-

supprised there were no codes- but not really. sometimes all it takes is a voltage loss or spike and the best of electronics can fail.

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