Fix for A/C issue??

[Jwhitney82]

My A/C temps at the vents are in the mid 50’s. Being that these trucks use 1234YF refrigerant this is normal imo. Unfortunately within the next couple years all vehicles manufactured will have to switch over as 134A is being phased out. Some manufacturers have shut off valves in place which does make a difference but the days of frost forming on the vents is long behind us.

 

[2019_Ram]

My A/C temps at the vents are in the mid 50’s. Being that these trucks use 1234YF refrigerant this is normal imo. Unfortunately within the next couple years all vehicles manufactured will have to switch over as 134A is being phased out. Some manufacturers have shut off valves in place which does make a difference but the days of frost forming on the vents is long behind us.

Please do not fall for this. This is absolutely not true. 1234yf is only in the 2019+ 1500 trucks for now, and has the ability to produce vent temps in the 30's. There are many on the 1500 boards who are getting these temps after bypassing the heater core. The 2019+ HD's are still using r134a. The 50* vent temps many see are due to a software or physical issue in the HVAC box of these trucks, not a refrigerant issue.

 

[Jwhitney82]

You are correct about the refrigerant. My mistake I haven’t had to service a newer 2500 yet only a 1500. Assumed they were the same. Here is a chart about vent temps in relation to temps outside.

 

[ahhhr]

Ill throw in my speculation....
Some guys have trucks where the sensor wires got flipped on a connector.
I have no complaints on my dual zone.

 

[IronByron]

Ill throw in my speculation....
Some guys have trucks where the sensor wires got flipped on a connector.
I have no complaints on my dual zone.

Same here, as I have always said. My AC works great. I don’t think my truck has ever left “auto”. But every time I mention that it doesn’t seem to be all trucks, folks tend to think it doesn’t get hot and humid where I live (it does).

 

[g00fy]

Ill throw in my speculation....
Some guys have trucks where the sensor wires got flipped on a connector.
I have no complaints on my dual zone.

This has crossed my mind also, and I talked to @Jimmy07 about taking a look at the wiring schematic to see if maybe rewiring the HVAC connector to correct the wonky data might fix straighten out the odd behavior.

 

[Burton12387]

Well, I got the valve picked up today. Here are a few pictures to show my thinking... This will hopefully pop into the coolant connector leaving the head and then the heater inlet pipe will connect to the open end. I had hope the valve would have been a little smaller, but I think it will still fit without issue.

Any updates on the install or effect on the AC?


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[2019_Ram]

Not yet. Had a few things pop up where I can't take the chance of having the truck down. So it's been put on hold right now. I did measure and it looks like it will be tighter than I had hoped getting the valve hooked up in there.

 

[thestuarts]

Any updates on the install or effect on the AC?

I installed a manual shutoff valve in my heater core loop today. The only materials were:

• Four Seasons 84706 Shut Off Valve $12.25
• 2 hose clamps @ $2.00 each

All I had to do was cut the heater core return line about 4 inches away from where it terminates and install the valve. It took about 15 minutes to install. I wanted to install the valve in the heater core inlet line, but then the valve would be inaccessible.

This weekend, I plan on using AlfaOBD and a good thermometer to log a bunch of data to determine if the valve actually helps. I will also get the AlfaOBD logs that @g00fy and @Jimmy07 want.

I suspect the valve won't actually help based on g00fy and Jimmy's analysis. But, if the valve helps even a little, I will probably keep it (or install an electronic valve).

 

[carlrx7]

sorry so many are having a/c issues. It's consistently 100+ here in Texas now. Inside cabin temp reads 118*. I have the a/c set to 70, 24/7 and never touch it... I vent the sunroof and open the back window for about 2-3 minutes at the start of a drive, then i can feel the air turn cool. About 10 minutes in, the fan starts to slow down. My definition of cool may be different than others. I wear a full sleeve and pants utility uniform, so pretty use to baking in the heat. However, it's nothing close to my Toyota's 07 Tundra/18 Camry. Those will both freeze you and your lunch box if left on "low"

 

[Burton12387]

I installed a manual shutoff valve in my heater core loop today. The only materials were:

• Four Seasons 84706 Shut Off Valve $12.25
• 2 hose clamps @ $2.00 each

All I had to do was cut the heater core return line about 4 inches away from where it terminates and install the valve. It took about 15 minutes to install. I wanted to install the valve in the heater core inlet line, but then the valve would be inaccessible.

This weekend, I plan on using AlfaOBD and a good thermometer to log a bunch of data to determine if the valve actually helps. I will also get the AlfaOBD logs that @g00fy and @Jimmy07 want.

I suspect the valve won't actually help based on g00fy and Jimmy's analysis. But, if the valve helps even a little, I will probably keep it (or install an electronic valve).

View attachment 5018View attachment 5019

Any feedback or new data yet?


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[thestuarts]

Any feedback or new data yet?

I did about 1 hour of driving today with the valve closed, so no hot water was flowing through the heater core. I couldn't tell a difference in the air conditioning. I planned to do some scientific experiments with a good refrigerant thermometer, but the thermometer I ordered didn't arrive in time. I will do experiments as soon as the thermometer arrives.

However, there is good news. @g00fy uncovered a potential problem in the way the temperature sensors are configured (or there is a bug in AlfaOBD). Go check out the update on the other thread:

Constantly adjusting heat

I am having issues with my 2019 ram 2500 heating and air conditioning. As I am driving the temperature will not stay constant. The other day it was a little chilly outside but had to set the timpratue at 66 degrees and I could feel the passenger side was much cooler air blowing out as compared...

hdrams.com

 

[Burton12387]

Is their any hazard to the engine cooling by blocking coolant flow that would have been coming off the top of the engine back near cylinder 5-6, would it be better to bypass the heater core instead of just stop flow?

I’m going to put some pliers on my heater core inlet side tomorrow and see if it affects my vent temps.


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[thestuarts]

Is their any hazard to the engine cooling by blocking coolant flow that would have been coming off the top of the engine back near cylinder 5-6, would it be better to bypass the heater core instead of just stop flow?

I believe I understand what you are saying, but here are a few diagrams to make sure I understand.

From the factory, this is a simplified version of how coolant flows through the engine, heater core, and radiator. Coolant always flows through the heater core, so it is providing a small amount of cooling even when the heater is off. We are trying to determine if the amount of heat extracted by the heater core (when off) is significant enough to affect the air conditioning system.



This is the modification I made:



I believe you are proposing to completely bypass the heater core to keep the hot water flowing out the top of the engine near cylinders 5-6:




When off, the amount of heat the heater core extracts from the coolant is very small because otherwise the interior of the cab would quickly get very hot. I can't imagine the engine cooling system is dependent on the extremely small amount of heat extracted by the heater core when off, but I agree that completely bypassing the heater core would maintain the same flow.

EDIT: Are you suggesting the coolant near cylinders 5-6 can only exit the engine out the top through the heater core? I believe it can still exit the engine with the coolant that circulates around the rest of the cylinders.

 

[Brutal_HO]

I believe I understand what you are saying, but here are a few diagrams to make sure I understand.

From the factory, this is a simplified version of how coolant flows through the engine, heater core, and radiator. Coolant always flows through the heater core, so it is providing a small amount of cooling even when the heater is off. We are trying to determine if the amount of heat extracted by the heater core (when off) is significant enough to affect the air conditioning system.

View attachment 5048

This is the modification I made:

View attachment 5050

I believe you are proposing to completely bypass the heater core to keep the hot water flowing out the top of the engine near cylinders 5-6:

View attachment 5049


When off, the amount of heat the heater core extracts from the coolant is very small because otherwise the interior of the cab would quickly get very hot. I can't imagine the engine cooling system is dependent on the extremely small amount of heat extracted by the heater core when off, but I agree that completely bypassing the heater core would maintain the same flow.

EDIT: Are you suggesting the coolant near cylinders 5-6 can only exit the engine out the top through the heater core? I believe it can still exit the engine with the coolant that circulates around the rest of the cylinders.

It wouldn't be very efficient, or even possible, to cool this power plant if the system was in any way dependent upon the heater core and small diameter lines.

 

[Burton12387]

I’m not suggesting it, because I don’t know. I’m asking if it will hurt anything within the engine to stop flow from that particular coolant outlet that would otherwise flow through the heater core, and then join the other coolant lines back at the standpipe on the turbo side of the engine. I’m not insinuating the heater core is responsible for helping cool the engine, but am just seeing if anyone can tell me that eliminating that portion of flow from the engine back to the standpipe is harmless.

Thanks for the response and diagrams! Worst case scenario, I put a T in line before the valve and connect to a T at the standpipe on the turbo side to maintain flow.

The jury is still out as to whether it’s a blend door issues (which the clamp test should tell me tomorrow) or if it’s also a software, sensor, wiring issue, as being described in the other thread.

If I wasn’t going to lose my a**, I’d trade in already.

Lesson learned. Don’t buy a vehicle again outside of summer.......


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[thestuarts]

Worst case scenario, I put a T in line before the valve and connect to a T at the standpipe on the turbo side to maintain flow.

That would create a bypass loop that enables coolant to bypass the heater core even when the valve is open, so you would reduce the overall flow through your heater core when you do want it hot. The resistance through the bypass loop would most likely be much less than the resistance through the heater core, so I suspect the majority of coolant would just bypass the heater core.

 

[thestuarts]

Worst case scenario, I put a T in line before the valve and connect to a T at the standpipe on the turbo side to maintain flow.

That would create a bypass loop that enables coolant to bypass the heater core even when the valve is open, so you would reduce the overall flow through your heater core when you do want it hot. The resistance through the bypass loop would most likely be much less than the resistance through the heater core, so I suspect the majority of coolant would just bypass the heater core.

This is the flow problem I'm describing. The flow through the heater core would be reduced even when you want heat because the coolant will prefer to take the path of least resistance around the heater core.

 

[Brutal_HO]

This is the flow problem I'm describing. The flow through the heater core would be reduced even when you want heat because the coolant will prefer to take the path of least resistance around the heater core.


View attachment 5051

Stuart, you would have to have a 3-way.

 

[thestuarts]

Stuart, you would have to have a 3-way.

I agree. A 3-way valve on the inlet side would be ideal.

I was just pointing out the problem with Burton's design. "Worst case scenario, I put a T in line before the valve and connect to a T at the standpipe on the turbo side to maintain flow."