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Quirky heater issue on Dodge Caravan...





Ron_O

Life, Liberty, & the Pursuit of Happiness
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#1
We've got a 2005 Dodge Caravan that we use for one of our work rigs, with the 2.4 liter 4 cylinder engine, and it's been an unbelievably good rig for us. Somewhere around 235k miles or so. I'm convinced I want to try to get 400k out of it. I seriously can't believe how good that motor and tranny's been for us, I've pulled a trailer all over the country with it, including one dump run that had 4900 lbs. of drywall in it. The trailer alone probably weighs 900 lbs. and I think the van is probably rated to tow 2500 lbs. LOL. I ran it to Michigan and back last winter just before the virus hit, fully loaded trailer on the way back (in the snow).

Around a year ago it started having quirky issues with the heater. Seemed to work when it wanted to and no amount of tweaking the controls would fix anything. When it works, it works perfectly. It got to the point that the only time it would come on was if it was already set to the on position, fan running and temp control turned half way or so, when the car was started. We had to make sure it was on before starting the car. If you start the car and then turn on the heater, nada.

One time we triggered it by turning on the AC when nothing else worked, and that wasn't instant, it was after turning it off and then back on, with the temp turned up high while doing so. That hasn't worked since. Didn't need the heater over the summer; sometimes we don't drive it for weeks or months.

Since then I haven't been able to figure out a damned thing to make it fire up. It came on without warning a few weeks back but if you turn it off or turn the temp down too low it likely won't come back on. But once it comes on, it'll work fine for the entire trip, temp controls and all, as long as you don't shut it off.

We are working on our projects up in Eastern Washington right now and it's too cold to make any 3 hour runs between projects without the heater. Last I checked, it was 24* outside. Today I'm going to replace the brakes and put the winter tires on (studded) and see if I can clean the heater switches to get something to work. But I'm ready to buy something else if I can't get this resolved. I'm not a fan of pulling dash boards apart. Haven't pulled the thermostat but maybe that's all it is.

Does it sound like the temp gauge, fan switch (off/on), or some other issue such as the thermostat? The first time it ever happened I figured it was a stuck thermostat so revved the motor super high climbing a hill in low gear and it triggered it to come on. I just figured I was forcing the thermostat open. But the van NEVER heats up, even when pulling a load on a hot day.

Seems like a very uncommon and quirky issue so I'm wondering if any you guys have ever come up with something like this. Again, if I jump in it right now and for whatever reason it starts working, it will work normally and perfectly. There is plenty of coolant in the radiator, never had a leak.

Who will win the lucky cigar? :unsure::cautious:
 

JTW_Jr

WheelGunner
#2
You said heat , but what happens when you turn it on ?
Does the fan blow ? Does it blow cold instead of hot ?
Things to check :
 

Ron_O

Life, Liberty, & the Pursuit of Happiness
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#3
You said heat , but what happens when you turn it on ?
Does the fan blow ? Does it blow cold instead of hot ?
Things to check :
Yeah it just blows cold if you turn it on. NEVER heats up at all, not even a little bit. Otherwise everything seems normal.
 

MAC702

LEGEN...wait for it... DARY!
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#4
Maybe thermostat is stuck open and engine block never reaches a good operating temperature? That was the problem with my old pickup once, but that was a diesel, so is much more susceptible.
 

JTW_Jr

WheelGunner
#5
Symptoms of a Bad or Failing Heater Control Valve
  1. Heater doesn't work. One of the first symptoms of a faulty heater control valve is a heater that fails to produce warm air. ...
  2. Leaking coolant. Another common symptom of an issue with the heater control valve is coolant leaks. ...
  3. Erratic heater behavior.
I would replace both that valve ( its a pain but only $15 ) and the Thermostat ( i replace mine every other year anyways).
 
#6
Your problem reminded me of this video. This guy explains things simply, it should help you do an easy diagnosis. Could be a bad heater core, not enough coolant, thermostat stuck open, or other reasons.
 

SixshooterSam

Making Automobiles Great Again
#7
I would be looking more at the blend door actuator as the culprit.

Feel both heater hoses. If both are uncomfortably hot to hold for long, that means hot coolant is flowing through the core, thus eliminating any underhood issues as the potential culprit. However, if one hose is noticeably cooler than the other, that will tell you to start looking for the reason why hot coolant is not flowing through the core.

It sounds more like a temperature blend door actuator issue. Very common problem on most modern American vehicles. It's the door that directs air either through the A/C evaporator core for cooling, or the heater core for heat. A far less likely but possible culprit would be the climate control head unit itself. But again, far less likely.

Sometimes it's not the door actuator itself (the actual servo motor), but rather the door itself that is the culprit. I've done several door replacements on Jeep Grand Cherokees, where the motor itself works fine, but the door spindle breaks and just spins, not moving the door. The door will occasionally move, but usually does not. In fact, that's exactly what you're describing here. That may very well be your issue.

Unfortunately, that requires dash removal to address. Not fun.

But the first thing to do is feel BOTH heater hoses, as close to the firewall as possible. They should both be too hot to hold for long if the engine is up to temperature. If they're both hot, your issue is under the dash, not underhood. If you hage a coolant flow issue, one of the hoses will not be nearly as hot as the other. If the engine is not warming up for some strange reason, the hoses won't be too hot to hold.
 
#8
I have been struggling with a very little to no heat issue for the last 25 years in a 94 Caravan, have spent well over $500 in diagnostics & non-repairs to troubleshoot and make it work. Every mechanic says the systems functions fine, B.S! Why does my heater put out hotter heat the warmer the outside air temp is? Crickets is all I get! Upon my own further digging into a no heat issue, I learned that at least the Gen 2 vans have serious heat issues, you have a Gen 4 so I don't know if they have the same problems? Either suck it up and deal with it or spend some coin and get a aux heater that plugs into the cig lighter to make up the difference which isn't much. Good Luck
 

Ron_O

Life, Liberty, & the Pursuit of Happiness
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#9
I would be looking more at the blend door actuator as the culprit.

Feel both heater hoses. If both are uncomfortably hot to hold for long, that means hot coolant is flowing through the core, thus eliminating any underhood issues as the potential culprit. However, if one hose is noticeably cooler than the other, that will tell you to start looking for the reason why hot coolant is not flowing through the core.

It sounds more like a temperature blend door actuator issue. Very common problem on most modern American vehicles. It's the door that directs air either through the A/C evaporator core for cooling, or the heater core for heat. A far less likely but possible culprit would be the climate control head unit itself. But again, far less likely.

Sometimes it's not the door actuator itself (the actual servo motor), but rather the door itself that is the culprit. I've done several door replacements on Jeep Grand Cherokees, where the motor itself works fine, but the door spindle breaks and just spins, not moving the door. The door will occasionally move, but usually does not. In fact, that's exactly what you're describing here. That may very well be your issue.

Unfortunately, that requires dash removal to address. Not fun.

But the first thing to do is feel BOTH heater hoses, as close to the firewall as possible. They should both be too hot to hold for long if the engine is up to temperature. If they're both hot, your issue is under the dash, not underhood. If you hage a coolant flow issue, one of the hoses will not be nearly as hot as the other. If the engine is not warming up for some strange reason, the hoses won't be too hot to hold.
I just watched a few videos after the one @JTW_Jr recommended and one involved pulling the dash and heater box out and that gave me a great reference point overall. Great advice from @SixshooterSam , basically what I gleaned from the videos as well. I'll have to get out there and do some basic troubleshooting but I'm thinking it's the blend flap as well. Reason is that if I try running it for a while (cold air) and then just shut it off, I can actually feel some residual WARM air blowing from around the vents, making me think the heat is down there but the flaps just aren't directing it right so the outside air is blowing residual heat past the vents. Makes more sense after watching the vids and seeing how it's all engineered.

The trouble is that thing is totally sealed up and I don't think there's any getting in there and jiggling something loose. I really don't think I'll pull that dash out because that's a b!tch that I don't think I'm up for. I had to replace a heater core on a Ford Taurus one time and it was like an 11 hour job round trip. But my concern with this van is that the Vegas heat took a toll on the plastics I think and I'm concerned that once I get inside I'll end up replacing the whole thing and I'd rather spend the $$ toward a replacement van or truck. Seems like the van as a whole is beginning to age-out a bit in that regard.

I now know a bit more about heater systems in general!

@awopahoe , based on what I've seen online today, it sounds like you have a heater core issue. You can pull the hoses from the engine and back flush it to clean it out with a garden hose, but you'll have to pull the dash to replace a bad core if it's totally plugged up. It could also be a blend flap door issue. Either way you'll have to pull that dash if yours is similar to mine. Read what @SixshooterSam wrote and do your own assessment.

Thanks guys, I'll let you know what I find. At least now I'm not just stabbing in the dark.
 
Last edited:

SixshooterSam

Making Automobiles Great Again
#10
I just watched a few videos after the one @JTW_Jr recommended and one involved pulling the dash and heater box out and that gave me a great reference point overall. Great advice from @SixshooterSam , basically what I gleaned from the videos as well. I'll have to get out there and do some basic troubleshooting but I'm thinking it's the blend flap as well. Reason is that if I try running it for a while (cold air) and then just shut it off, I can actually feel some residual WARM air blowing from around the vents, making me think the heat is down there but the flaps just aren't directing it right so the outside air is blowing residual heat past the vents. Makes more sense after watching the vids and seeing how it's all engineered.

The trouble is that thing is totally sealed up and I don't think there's any getting in there and jiggling something loose. I really don't think I'll pull that dash out because that's a b!tch that I don't think I'm up for. I had to replace a heater core on a Ford Taurus one time and it was like an 11 hour job round trip. But my concern with this van is that the Vegas heat took a toll on the plastics I think and I'm concerned that once I get inside I'll end up replacing the whole thing and I'd rather spend the $$ toward a replacement van or truck. Seems like the van as a whole is beginning to age-out a bit in that regard.

I now know a bit more about heater systems in general!

@awopahoe , based on what I've seen online today, it sounds like you have a heater core issue. You can pull the hoses from the engine and back flush it to clean it out with a garden hose, but you'll have to pull the dash to replace a bad core if it's totally plugged up. It could also be a blend flap door issue. Either way you'll have to pull that dash if yours is similar to mine. Read what @SixshooterSam wrote and do your own assessment.

Thanks guys, I'll let you know what I find. At least now I'm not just stabbing in the dark.
One thing to remember, always to remember on all vehicles.. you must diagnose your own issue on your vehicle, not base anything on videos or writeups you may find that describe the same or similar issue. Any time you ask about a vehicle problem on the internet, you will get 137 different answers, all from people who say they had the EXACT same issue, all with a different "fix".

There is nothing mysterious about these systems and they are in fact easy to diagnose if you actually have access to the vehicle. Things get out of whack fast when you try to diagnose things over the internet based on the often times inaccurate description of symptoms provided. I could not tell you the number of times I looked at a customer's vehicle, and the symptoms they described over the phone were unrecognizable to what I was actually seeing - triple especially when people try to tell me what they think it is this or that. You have to throw all of that out of the window and focus on the vehicle itself, as it will tell you the real story.

These vehicles were designed and built by man. They can be diagnosed and fixed just as readily by man, so long as you understand all the systems and how they work. Unfortunately, most "mechanics" lack serious in-depth knowledge and understanding of how the systems work, so they are not prepared to properly diagnose them, let alone repair them. Hence why so many people tell so many stories of so many mechanics who could not figure out their problem, despite throwing parts at it repeatedly and charging the customer for all their mistakes.

But then the same knucklehead customers who get swindled by these hacks go on and defend them at length on account of them always having fresh coffee and donuts in the waiting room, their kid plays soccer with their kid and they always give them a 10% discount, despite charging 30% more per hour than the next guy. Most people are fooled by niceties and taken by hacks. That's just the way of things in this business unfortunately.
 

Ronsmag

I'm a schizophrenic and so am I
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#11
I would be looking more at the blend door actuator as the culprit.

Feel both heater hoses. If both are uncomfortably hot to hold for long, that means hot coolant is flowing through the core, thus eliminating any underhood issues as the potential culprit. However, if one hose is noticeably cooler than the other, that will tell you to start looking for the reason why hot coolant is not flowing through the core.

It sounds more like a temperature blend door actuator issue. Very common problem on most modern American vehicles. It's the door that directs air either through the A/C evaporator core for cooling, or the heater core for heat. A far less likely but possible culprit would be the climate control head unit itself. But again, far less likely.

Sometimes it's not the door actuator itself (the actual servo motor), but rather the door itself that is the culprit. I've done several door replacements on Jeep Grand Cherokees, where the motor itself works fine, but the door spindle breaks and just spins, not moving the door. The door will occasionally move, but usually does not. In fact, that's exactly what you're describing here. That may very well be your issue.

Unfortunately, that requires dash removal to address. Not fun.

But the first thing to do is feel BOTH heater hoses, as close to the firewall as possible. They should both be too hot to hold for long if the engine is up to temperature. If they're both hot, your issue is under the dash, not underhood. If you hage a coolant flow issue, one of the hoses will not be nearly as hot as the other. If the engine is not warming up for some strange reason, the hoses won't be too hot to hold.
I just had to do this (blend door actuator) to my Chrysler 300 there are four in my 300 and they all needed to be changed it did some weird stuff blowing hot when it was off no A/C then A/C only it's crazy Mine made noise like something caught in a fan at first it was loud and then it was very low barely hear it
 
Last edited:

Harley

Golf-Foxtrot-Yankee
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#15
It's an electric servo motor on that van. I don't think anything in the 2000s used vacuum for climate control duties.
If memory serves me correctly, wasnt the Astro van Vacuum operated til mid 00s??

I could be wrong but it sticks in my head for some reason.
 

SixshooterSam

Making Automobiles Great Again
#16
CALIBRATION/DIAGNOSTICS TEST ENTRY
TO INITIATE TESTS:
Set Blower motor ON HIGH
Set Mode position to Panel
Open all A/C outlets
Set Temperature to Cold (Both slide pots if equipped)
Depress WASH and REAR WIPER button simultaneously for 5 Seconds (Until all LED's light)
RESULTS:
All LED's will turn on for 5 Seconds
Calibration Test is running when REAR WIPER and INTERMITTENT are alternately flashing. Cooldown test is running if A/C and RECIRC are alternately flashing.
Acceptable results is REAR WIPER LED is the only LED flashing. Push Rear Wiper to exit.
After all tests have passed, Calibration Diagnostics and Cooldown can be run separately.
COOLDOWN TEST ENTRY
TO INITIATE TESTS:
Set Blower motor ON HIGH
Set Mode position to Panel
Open all A/C outlets
Set Temperature to Cold (Both slide pots if equipped)
Depress WASH and A/C simultaneously for 5 Seconds
NOTE: Prior to start of test, If the evaporator is already cold, the system will fail test. To correct, operate system with A/C OFF and the blower motor ON high for three minutes prior to starting test.

RESULTS:
All LED's will turn on for 5 Seconds
Cooldown Test is running when A/C and RECIRC. are alternately flashing. If A/C and RECIRC. are flashing simultaneously, Cooldown has failed.
CALIBRATION DIAGNOSTICS AND COOLDOWN ABORT
Test can be aborted by doing one of the following:

Depressing Rear Window Defogger, RECIRC and Rear Wiper buttons.
Cycling Ignition OFF and then ON.
Control will automatically abort after 15 minutes from the time Calibration Diagnostics and Cooldown was entered.
The HVAC control module will return to normal operation or may indicate unsuccessful Calibration Diagnostics or Cooldown test by LED's flashing simultaneously.

EEPROM DATA
Calibration Diagnostics, Cooldown Status and evaporator temperature Fin Sensor values are stored in an EEPROM memory internal to the control. The microcomputer within the HVAC control module uses this information:

To determine if Cooldown needs to run
For proper position of the Heater-A/C unit assembly doors
ACTUATOR CALIBRATION AND DIAGNOSTICS
NOTE: Do not run actuators unless they are properly mounted on the HVAC control module.

Actuator end point calibration takes approximately 60 seconds. The REAR WIPER and INTERMITTENT LED's will flash alternately during the test. The control will cycle the Blend actuator(s) to the Heat stop first then back to Cold. After the Blend actuator(s) have been calibrated the Mode actuator will be cycled to Defrost and then to Panel. Successful calibration is defined as actuator travel falling within their minimum and maximum limits.
 

SixshooterSam

Making Automobiles Great Again
#17
If memory serves me correctly, wasnt the Astro van Vacuum operated til mid 00s??

I could be wrong but it sticks in my head for some reason.
Couldn't tell you. Astro vans are garbage and I don't work on them. I don't work on these Dodges either, but they share the same basic climate control actuators and functionality as the other Mopar products of the time period which I have worked on, namely Jeeps and the Charger/300.
 

Ron_O

Life, Liberty, & the Pursuit of Happiness
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2020 Supporter
#18
One thing to remember, always to remember on all vehicles.. you must diagnose your own issue on your vehicle, not base anything on videos or writeups you may find that describe the same or similar issue. Any time you ask about a vehicle problem on the internet, you will get 137 different answers, all from people who say they had the EXACT same issue, all with a different "fix".

There is nothing mysterious about these systems and they are in fact easy to diagnose if you actually have access to the vehicle. Things get out of whack fast when you try to diagnose things over the internet based on the often times inaccurate description of symptoms provided. I could not tell you the number of times I looked at a customer's vehicle, and the symptoms they described over the phone were unrecognizable to what I was actually seeing - triple especially when people try to tell me what they think it is this or that. You have to throw all of that out of the window and focus on the vehicle itself, as it will tell you the real story.

These vehicles were designed and built by man. They can be diagnosed and fixed just as readily by man, so long as you understand all the systems and how they work. Unfortunately, most "mechanics" lack serious in-depth knowledge and understanding of how the systems work, so they are not prepared to properly diagnose them, let alone repair them. Hence why so many people tell so many stories of so many mechanics who could not figure out their problem, despite throwing parts at it repeatedly and charging the customer for all their mistakes.

But then the same knucklehead customers who get swindled by these hacks go on and defend them at length on account of them always having fresh coffee and donuts in the waiting room, their kid plays soccer with their kid and they always give them a 10% discount, despite charging 30% more per hour than the next guy. Most people are fooled by niceties and taken by hacks. That's just the way of things in this business unfortunately.
LIVING PROOF that donuts and coffee serve effectively as bribe inducement mechanisms.

I agree with you on the 'out of your league' comments as far as understanding/repairing heaters. That's the primary reason I've put this off for so long and came here for advice, simply due to the fact that I didn't fully understand how the entire system was put together, combined with the fact that I hate getting under the dash. Just getting old, I guess.

I wasn't able to break off and get to it yesterday, and we woke to heavy snow this morning so I'll have to wait until I can pull the boat out without worrying about weather. I keep the boat in my repair bay right now. I can go weeks or months without using the van and with the snow it may not be a while before it's needed again. Hopefully things will dry out sooner rather than later.

Thanks for all your help, everyone. I think this thing will be pretty easy to diagnose. I have no plans of pulling that unit out, so if it's not something relatively simple the van will be relegated to seasonal use or sold off or given away to a friend in need. I have my eyes on another pair of vans in Oregon but my co-driver just left town so I can't make the trip down to pick anything up anytime soon, unless I find another driver. Six hours each way.

But even with the snow I can start it up and troubleshoot this issue. It's the brakes and snow tires that will have to wait, and if I sell it I'll leave the snow tires in the shop and keep them for use on something else.
 

Ron_O

Life, Liberty, & the Pursuit of Happiness
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2020 Supporter
#19
I would be looking more at the blend door actuator as the culprit.

Feel both heater hoses. If both are uncomfortably hot to hold for long, that means hot coolant is flowing through the core, thus eliminating any underhood issues as the potential culprit. However, if one hose is noticeably cooler than the other, that will tell you to start looking for the reason why hot coolant is not flowing through the core.

It sounds more like a temperature blend door actuator issue. Very common problem on most modern American vehicles. It's the door that directs air either through the A/C evaporator core for cooling, or the heater core for heat. A far less likely but possible culprit would be the climate control head unit itself. But again, far less likely.

Sometimes it's not the door actuator itself (the actual servo motor), but rather the door itself that is the culprit. I've done several door replacements on Jeep Grand Cherokees, where the motor itself works fine, but the door spindle breaks and just spins, not moving the door. The door will occasionally move, but usually does not. In fact, that's exactly what you're describing here. That may very well be your issue.

Unfortunately, that requires dash removal to address. Not fun.

But the first thing to do is feel BOTH heater hoses, as close to the firewall as possible. They should both be too hot to hold for long if the engine is up to temperature. If they're both hot, your issue is under the dash, not underhood. If you hage a coolant flow issue, one of the hoses will not be nearly as hot as the other. If the engine is not warming up for some strange reason, the hoses won't be too hot to hold.
Well you nailed it. Thanks. Got out there and heated the motor up and both hoses were hot, including inside under the dash, so the heater core is definitely doing its job.

I'm going to see if there's a way to get under that dash and manipulate the blend door open to the heat side and just leave it there, leaving it wide open for full heat. Then I can just control it with the fan switch. That'll get me through the winter. Not sure if I can get under there and manipulate anything, however, so that'll be my next step. Pulling the dash isn't in the cards for me with this van and not worth paying someone to do. Time to upgrade to something else.

Appreciate the help and advice!
 

Harley

Golf-Foxtrot-Yankee
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#20
under the drivers side of the dash there should be a panel you can remove to access the actuators.

Here’s what you’re looking for.

3622A573-CB45-45A0-A61A-665772F84169.jpeg 5BF68066-56E3-4FAE-B729-B94764D07781.jpeg
A new one is about $30 give or take depending on where ya buy it from.