Fix for A/C issue??

[Burton12387]

Any insight to any negative effects of just cutting off flow for the summer?


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[jakalafus]

Has anyone figured out of this even fixes anything?

 

[thestuarts]

Any insight to any negative effects of just cutting off flow for the summer?

I am not a car mechanic, so you should be skeptical of my opinions.

Preventing coolant from flowing through the heater core for an extended period of time might contribute to corrosion and buildup in the heater core.

Cutting the flow on the outlet side (like I did) causes pressurization of the heater core, so it is probably safer to cut flow on the inlet side (like you are recommending).

It is theoretically, but very remotely, possible cutting heater core flow could cause weird flow problems in the engine. Imagine cavitation near the outlet port on top of the engine where coolant normally exits. It might create hot spots which would result in unequal thermal expansion creating gaps and leaks. I think the actual probability of this problem approaches zero.

I don't know if the turbo coolant flow will be affected by cutting the heater core flow. Maybe the turbo coolant flow partially relies on the venturi effect of the heater core flow. I really doubt that's the case.

Overall, I believe the risk is low, but hopefully someone with a mechanic background can provide their perspective.

 

[thestuarts]

Has anyone figured out of this even fixes anything?

I drove around for an hour yesterday with the heater core flow blocked. I didn't notice any difference using my skin as a thermometer.

My wife was with me, but she didn't know about the experiment. At the end of the trip, I asked my wife if she noticed anything different with the air conditioning. Ironically, she said it felt warmer than usual, so it definitely didn't have an immense effect on improving the air conditioning.

I will do some scientific experiments as soon as a thermometer arrives.

 

[Burton12387]

I just put a sock and vice grip on the discharge side of the heater core above the turbo just to test it.

Previously they best temps i would ever see out of the driver side dash was 54-55 degrees. With the clamp temp Installed it was 45-46 degrees, and back on par with the passenger vents.

This somewhat reassures me that I have a blend door sealing issue and not a refrigerant/software/ sensor issue.

I have an appt scheduled for Tuesday, but I’m debating not wasting my time, and risking the dealership screwing up something on the truck. But I’m also tempted to try and ask them to calibrate the doors? I’m still confident I’ll be told “operating as designed” I can see why there are some who do actually have good ac. Somewhere there must be a bad batch of blend doors or bad calibration of blend doors. Thankfully, you only have to remove the whole dash to evaluate or repair. Sigh. (They can calibrate with Autel or similar with no dash removal, you just won’t be able to see anything).

My efforts are probably better spent putting a valve on the inlet side of the heater core. What do you think? Ask to calibrate doors? Or just valve off the core.

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[thestuarts]

I just put a sock and vice grip on the discharge side of the heater core above the turbo just to test it.
Previously they best temps i would ever see out of the driver side dash was 54-55 degrees. With the clamp temp Installed it was 45-46 degrees, and back on par with the passenger vents.

That's a good lead on your problem. Here's what I would do to confirm the experiment.

1. Get the truck to operating temperature with the hose clamped. Turn on the A/C and measure the vent temperature on both sides.
2. With the truck still running, remove the clamp. Wait a few minutes and measure the temperature on both sides.
3. Clamp the hose again. Wait a few minutes and measure the temperature on both sides.

See if removing the clamp causes the temperature to increase and reapplying the clamp causes the temperatures to decrease.

 

[Brutal_HO]

3-way joke did not go as planned. Poorly executed phrasing I suspect but I'll need to gather some log data.

 

[Brutal_HO]

I just put a sock and vice grip on the discharge side of the heater core above the turbo just to test it.

Previously they best temps i would ever see out of the driver side dash was 54-55 degrees. With the clamp temp Installed it was 45-46 degrees, and back on par with the passenger vents.

This somewhat reassures me that I have a blend door sealing issue and not a refrigerant/software/ sensor issue.

I have an appt scheduled for Tuesday, but I’m debating not wasting my time, and risking the dealership screwing up something on the truck. But I’m also tempted to try and ask them to calibrate the doors? I’m still confident I’ll be told “operating as designed” I can see why there are some who do actually have good ac. Somewhere there must be a bad batch of blend doors or bad calibration of blend doors. Thankfully, you only have to remove the whole dash to evaluate or repair. Sigh. (They can calibrate with Autel or similar with no dash removal, you just won’t be able to see anything).

My efforts are probably better spent putting a valve on the inlet side of the heater core. What do you think? Ask to calibrate doors? Or just valve off the core.




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I'd let them know right up front you suspect blend door issues and ask for visual proof it's "working as designed." They can bore-snake it and look if needed.

 

[carlrx7]

I



I can report my passenger side is about 10 degrees cooler than my drivers side.

Driver side 40 avg
Passenger 30 avg

Side note: It feels cooler when I turn off my vented seats. This is with them off.

 

[Burton12387]

Carlx7, can you give more info on the year and build date of your truck? Those are crazy low numbers, and the first I’ve seen that low out of a ram. Hell, I’d be tickled if both vents blew 45 degrees.

So much for people being told “operating as designed” 15 degree variance among the same design is a hell of a spread.......


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[Jwhitney82]

IView attachment 5074

View attachment 5075

I can report my passenger side is about 10 degrees cooler than my drivers side.

Driver side 40 avg
Passenger 30 avg

Side note: It feels cooler when I turn off my vented seats. This is with them off.

I’ve worked in the automotive field for 20 years and I’ve never seen numbers that low. I’d check your equipment and there’s always a difference from one side to another.

 

[carlrx7]

I'm going to use a temp probe tomorrow and see if the numbers are consistant. My truck info is in my sig.

 

[thestuarts]

Today, I finished my experiment with the heater core valve. I believe I have proven the heater core loop significantly affects the air conditioning temperature.

Test Methodology:

1. The truck was cold and hadn't been run in 24 hours.
2. I put digital thermometer probes in all 4 vents.
3. I recorded the ambient temperature in all vents which was between 99 degrees and 104 degrees.
4. The outside ambient temperature was recorded at 84 degrees.
5. I started the truck and immediately put the air conditioning into manual LO mode with recirculation enabled. This eliminates the potential software/sensor problem because in LO mode the truck tries to reach 0 Celcius.
6. Every 30 seconds, I logged the temperature reading on all 4 vents and I also recorded the engine temperature.
7. Within 5 minutes, all 4 vents reached their low point, but the engine was still way below nominal operating temperature.
8. I observed the vent temperatures started to increase as the engine temperature increased above 120 degrees.
9. I continued to log the temperature of the vents and engine until the engine reached thermal equilibrium at 188 degrees.
10. Once the engine reached thermal equilibrium, I closed the valve blocking the heater core loop.
11. Within a few minutes the vent temperatures dropped noticeably. In particular, the driver's right vent dropped by 7 degrees.
12. After the vents stabilized at their low temperature, I opened the valve blocking the heater core loop.
13. The vent temperatures rose within a few minutes. The driver's right vent increased by 7 degrees.
14. After the vents stabilized at their high temperature, I closed the valve blocking the heater core loop.
15. Within a few minutes, the vent temperatures dropped by up to 7 degrees.
16. After the vents stabilized at their low temperature, I opened the valve blocking the heater core loop.
17. Within a few minutes, the vent temperatures increased by up to 7 degrees.

Observations:

• Closing the heater core loop causes the temperature to decrease by 7 degrees in the driver's right vent.
• Opening the heater core loop causes the temperature to increase by 7 degrees in the driver's right vent.
• The heater core loop is definitely interfering with the A/C .
• The driver's right vent is the most affected, while the passenger's left vent is the least affected.
• The driver's side always puts out warmer air than either of the passenger vents. If your passenger is complaining about it being too cold, they may be right.
• I did this experiment on an 84 degree day. I suspect the problem is worse when the ambient temperature is even hotter.
• I suspect there is a separate problem with the computer/sensors not being configured properly which is exacerbating the problem.

I uploaded a video to YouTube if you want to review the test methodology:

Here is a chart showing the vent temperature after closing and opening the valve blocking the heater core. The engine was at thermal equilibrium.


Edit: Here is another view of the same chart that is easier to read on a phone.

 

[Gondul]

Excellent video @thestuarts thanks for doing this work.

Hey @RamCares this is something you need to take note of and report up the chain...

 

[Cummins3]

Dealer said to me within spec 45 I need to check myself

 

[Brutal_HO]

Today, I finished my experiment with the heater core valve. I believe I have proven the heater core loop significantly affects the air conditioning temperature.

Test Methodology:

1. The truck was cold and hadn't been run in 24 hours.
2. I put digital thermometer probes in all 4 vents.
3. I recorded the ambient temperature in all vents which was between 99 degrees and 104 degrees.
4. The outside ambient temperature was recorded at 84 degrees.
5. I started the truck and immediately put the air conditioning into manual LO mode with recirculation enabled. This eliminates the potential software/sensor problem because in LO mode the truck tries to reach 0 Celcius.
6. Every 30 seconds, I logged the temperature reading on all 4 vents and I also recorded the engine temperature.
7. Within 5 minutes, all 4 vents reached their low point, but the engine was still way below nominal operating temperature.
8. I observed the vent temperatures started to increase as the engine temperature increased above 120 degrees.
9. I continued to log the temperature of the vents and engine until the engine reached thermal equilibrium at 188 degrees.
10. Once the engine reached thermal equilibrium, I closed the valve blocking the heater core loop.
11. Within a few minutes the vent temperatures dropped noticeably. In particular, the driver's right vent dropped by 7 degrees.
12. After the vents stabilized at their low temperature, I opened the valve blocking the heater core loop.
13. The vent temperatures rose within a few minutes. The driver's right vent increased by 7 degrees.
14. After the vents stabilized at their high temperature, I closed the valve blocking the heater core loop.
15. Within a few minutes, the vent temperatures dropped by up to 7 degrees.
16. After the vents stabilized at their low temperature, I opened the valve blocking the heater core loop.
17. Within a few minutes, the vent temperatures increased by up to 7 degrees.

Observations:

• Closing the heater core loop causes the temperature to decrease by 7 degrees in the driver's right vent.
• Opening the heater core loop causes the temperature to increase by 7 degrees in the driver's right vent.
• The heater core loop is definitely interfering with the A/C .
• The driver's right vent is the most affected, while the passenger's left vent is the least affected.
• The driver's side always puts out warmer air than either of the passenger vents. If your passenger is complaining about it being too cold, they may be right.
• I did this experiment on an 84 degree day. I suspect the problem is worse when the ambient temperature is even hotter.
• I suspect there is a separate problem with the computer/sensors not being configured properly which is exacerbating the problem.

I uploaded a video to YouTube if you want to review the test methodology:

Here is a chart showing the vent temperature after closing and opening the valve blocking the heater core. The engine was at thermal equilibrium.
View attachment 5124

Edit: Here is another view of the same chart that is easier to read on a phone.

View attachment 5131

Very well done video Alan. Don't hesitate to put your vids on youtube, you're doing a great job with them!

 

[carlrx7]

so coolant is flowing through only the drivers side. should be easy to narrow down now. Heater core could be used to prevent freezing up??

 

[jakalafus]

Anyone know what this magic “to spec” that FCA has is?

 

[Gondul]

Anyone know what this magic “to spec” that FCA has is?

S h i t t y....

 

[Brutal_HO]