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Discussion Starter · #1 · (Edited)
Friends, I'm desperate, I can't figure this out.

I have a 2010 T&C Limited with 4.0L and 3-zone ATC.

The car has little to no heat.

What I have done so far:
1) Topped off coolant, it's full
2) Replaced thermostat, original was fine.
3) Replaced cabin air filter (was very dirty). No difference.
4) Pulled apart dash and checked all blend door servos; all working.
5) Held the AUTO/SYNC button on the ATC to calibrate doors, no errors I can hear all front and rear servos cycle.
6) Pulled lines to heater core and reverse flushed them, some minor junk came out (coolant does have rusty color). Core runs freely. Inlet gets very hot, outlet still stays cold.

None of this has worked, still have no heat.

At idle, van blows cold air.
Revving the engine produces some heat, barely.
Driver's side in center console upper vents is warmish, passenger side is cold, never gets warm even on engine rev.

I have noticed that the A/C compressor clutch cycles on and off while idling - that's odd since it's 20 degrees outside here.

Bottom line, I'm out of ideas, and it's very cold here in the Northeast.

Any ideas? There is so little information on troubleshooting 4.0L vans. I've been all over many forums and YouTube with no luck.

Thank you!
 

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Topped up coolant in radiator or reservoir?
Engine temperature?
Temperature of heater lines at firewall? Cold line indicates a lack of circulation. Do you have rear heat? a plastic inline flow restrictor?
 
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Discussion Starter · #4 · (Edited)
Topped up coolant in radiator or reservoir?
Engine temperature?
Temperature of heater lines at firewall? Cold line indicates a lack of circulation. Do you have rear heat? a plastic inline flow restrictor?
Coolant is full at radiator, overflow is at max. Car warms up to proper operating temperature just fine.

Yes, I have rear heater, but no heat there either. My plastic y-pipes were replaces with metal ones 2 years ago.

Lines at firewall; one is hot, other is cold.

What is the "inline flow restrictor"
 

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Both lines should be hot.

Remove the cold line and make sure coolant is flowing.
Also you can check the heater return line to the water pump to see if somebody blocked it off. Something is amiss, your heater core was flushed, one line is hot, so circulation is blocked somewhere.
 

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Discussion Starter · #7 · (Edited)
Also you can check the heater return line to the water pump to see if somebody blocked it off. Something is amiss, your heater core was flushed, one line is hot, so circulation is blocked somewhere.
I agree, but I have no idea where that could be. There is a connection right from the back of the thermostat housing to the heater core, then right back to the water pump. There is literally nothing in that path but a straight shot from engine, to core, to water pump.

I'm completely stumped.

Could the water pump be bad? Wouldn't the car be overheating then?

The car does have 130,000 miles on it, and still the original timing belt (I'm original owner). Could a loose (stretched) timing belt be the issue?
 

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According to your first post, the heater core is not plugged, the blend doors work, the hoses going in and out of the core are different temperatures and yet you have no heat.
The only way this could happen is if the flow thru the heater core was very low.
or....you have made an error in your first post.
I find it odd that you also have no rear heat. Perhaps this is a clue.
Suggestion, remove the heater hoses from the core, join the two hoses with a clear hose so you can watch the fluid flow.
While the hoses are off the core. You should be able to blow thru the core with the air pressure from your mouth to once again verify the core is not blocked.

I think if you had a bad water pump, the engine would have serious over heating problems.
 

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Discussion Starter · #9 ·
According to your first post, the heater core is not plugged, the blend doors work, the hoses going in and out of the core are different temperatures and yet you have no heat.
The only way this could happen is if the flow thru the heater core was very low.
or....you have made an error in your first post.
I find it odd that you also have no rear heat. Perhaps this is a clue.
Suggestion, remove the heater hoses from the core, join the two hoses with a clear hose so you can watch the fluid flow.
While the hoses are off the core. You should be able to blow thru the core with the air pressure from your mouth to once again verify the core is not blocked.

I think if you had a bad water pump, the engine would have serious over heating problems.
Yes, I agree it's odd. Let me tell you how I checked the heater core. I removed both hoses and ran a garden hose into the outlet side. Water came out at a trickle, then a little bit of junk, then a full flow. I reversed the garden hose to inlet, and it flowed out the outlet just fine. I did this 3 or 4 times, and each time the core flowed freely filling the pipes as water rolled out. I then blew all the water out and poured in coolant until it tricked out. I then took off radiator cap, ran the car, added coolant directly to radiator until it stopped taking fluid. I let the car heat up until the thermostat opened, topped off the radiator and replaced the cap.

Still no heat. I have a 4.0L, so I know the water pump and hose routing is very different. Water pump replacement requires timing chain cover removal on the 4.0L. Much bigger job.

I wish it was a simple clogged something, but if it is I can't find it.

On the 4.0L coolant flows from the engine to a "Y", with one hose headed to the rear heater, and one the front heater. Both returns come back to another "Y", and then right back to the water pump.

Seems so straight forward.
 

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Take the return off of the thermostat. Cap or plug the thermostat. Fill up the radiator. If you don't get anything, crank up and fill radiator again. By then you should have something coming out. Once it starts it should flow pretty good. That would mean you just had a stubborn air pocket.

If it just dribbles and drips, it's clogged. Time to start disconnecting stuff. Keep the radiator filled throughout testing. Run engine after disconnects if needed to push air trapped behind a clog. Work your way back to the Y and disconnect it. If that improves flow from both heater cores, you found the clog. If only from one, the other is clogged. If one or both are clogged disconnect it at the core, then the inlet, then the Y, then the water pump until you finally get flow. Whatever the last thing you disconnected from was once you get flow is what's clogged. It may be clogged down the line too, but that's the start of the clog.
 
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I have a feeling you don’t have enough impeller left on your water pump. Have you changed the water pump?

I recently did a water pump on a Honda van that had no impeller left. They do rot!


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Discussion Starter · #12 ·
I have a feeling you don’t have enough impeller left on your water pump. Have you changed the water pump?

I recently did a water pump on a Honda van that had no impeller left. They do rot!


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That's what I'm thinking. But on the 4.0 it's a major job to replace. Does anyone know if the 4.0L engine has a plastic impeller?
 

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When you flushed the heater core you said some junk/dirt came out. It would be reasonable to assume that the hoses, "Y" joints and any other bend or fitting in the heater hose circuit could be restricted. You could remove most of the hoses, look inside them, flush them, examine where the hoses connect to the engine. Do you see debris/restrictions? Connect good hoses directly to the engine and from there to the front heater core only. Does this produce heat?
If the water pump was so bad that you have only %5 heat, I think you would see problems with engine temperature regulation.
Temporary clear vinyl hose could help you see the flow rate.
 

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That's what I'm thinking. But on the 4.0 it's a major job to replace. Does anyone know if the 4.0L engine has a plastic impeller?
It sure does. Good time to change the timing belt and components while in there. That belt snapping is a whole 'nother level of headache.
 

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Discussion Starter · #15 ·
OK, here's an update. I took off ALL the heater line hoses and flushed them all. Reverse and forward flushed. I took off the lines to the oil cooler and flushed them too.

I still have very poor heat. At idle I have almost no heat. If I rev the engine a bit, I get heat.

I'm thinking the timing belt is stretched or the tensioner shot.

Is it possible the timing belt is slipping on the water pump pulley? That's my current working theory, now that I am certain coolant can properly cycle through the heating system.
 

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Not likely it's slipping. Likely it's worn down and is practically spinning a smooth shaft instead of an impeller, as many have already suggested.

If no clogs or leaks, the water pump is the issue.
 

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I still have very poor heat. At idle I have almost no heat. If I rev the engine a bit, I get heat.

I'm thinking the timing belt is stretched or the tensioner shot.

Is it possible the timing belt is slipping on the water pump pulley? That's my current working theory, now that I am certain coolant can properly cycle through the heating system.
Did you lose cabin heat out of the blue? Or did it happen after cooling system maintenance?
Do you mean a slipping serpentine belt? I think that's unlikely at idle speed and it would also affect the alternator.
Could be just that the heater core is air-bound, that would be an explanation for the hot in / cold out scenario.
Does the 2010 have "air vents" on the cooling system? My 2005 Chev Uplander had two vent screws which were necessary for removing the trapped air. Basically the same symptoms you are describing.
 

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Friends, I'm desperate, I can't figure this out.

I have a 2010 T&C Limited with 4.0L and 3-zone ATC.

The car has little to no heat.

What I have done so far:
1) Topped off coolant, it's full
2) Replaced thermostat, original was fine.
3) Replaced cabin air filter (was very dirty). No difference.
4) Pulled apart dash and checked all blend door servos; all working.
5) Held the AUTO/SYNC button on the ATC to calibrate doors, no errors I can hear all front and rear servos cycle.
6) Pulled lines to heater core and reverse flushed them, some minor junk came out (coolant does have rusty color). Core runs freely. Inlet gets very hot, outlet still stays cold.

None of this has worked, still have no heat.

At idle, van blows cold air.
Revving the engine produces some heat, barely.
Driver's side in center console upper vents is warmish, passenger side is cold, never gets warm even on engine rev.

I have noticed that the A/C compressor clutch cycles on and off while idling - that's odd since it's 20 degrees outside here.

Bottom line, I'm out of ideas, and it's very cold here in the Northeast.

Any ideas? There is so little information on troubleshooting 4.0L vans. I've been all over many forums and YouTube with no luck.

Thank you!
 

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Mine is doing the exact same thing but the water pump, timing belt, front and heater core was replaced and air and water blew threw everything fine with no clog and still no cabin heat front or back. I’m thinking about taking it to Chrysler to have a HVAC check.
 
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