A/C Performance

[Checkairspeed]

Dang. Thought Streetsweeper had all the answers.

In all seriousness. I’m glad that those that had an issue now have a fix. I continue to be satisfied with mine.

 

[Streetsweeper]

Dang. Thought Streetsweeper had all the answers.

He does.

 

[Streetsweeper]

No, the A/C issue has nothing to do with the heater hoses diameter. It is a combination of the blend doors not sealing correctly (hence the reason for the new HVAC box part number), a duct temp sensor location (the reason for the new distribution box part number and new temp sensor), and HVAC module mapping (the reason for the new HVAC module part number).

No. I worked ~50ft from where the HVAC was designed. Production-level hoses raised the outlet temperature.

 

[Jimmy07]

No. I worked ~50ft from where the HVAC was designed. Production-level hoses raised the outlet temperature.

So, what you are trying to tell us is- the two physically different distribution boxes, two physically different HVAC boxes, and the two different HVAC modules with wiring harness that I’ve seen on the bench side by side, were all done/redesigned for nothing for the TSB that fixes the A/C issue. You’re trying to tell us that all they needed to do is choke the coolant flow permanently going through the heater core by installing smaller diameter heater hoses, potentially causing a cabin heating issue in the winter time. Is that what you’re trying to convince us of?

 

[Streetsweeper]

So, what you are trying to tell us is- the two physically different distribution boxes, two physically different HVAC boxes, and the two different HVAC modules with wiring harness that I’ve seen on the bench side by side, were all done/redesigned for nothing for the TSB that fixes the A/C issue. You’re trying to tell us that all they needed to do is choke the coolant flow permanently going through the heater core by installing smaller diameter heater hoses, potentially causing a cabin heating issue in the winter time. Is that what you’re trying to convince us of?

1st, I'll prescribe you a chill-pill.

What I can tell you is changing plastic molded part design is very cheap (relatively). Cannot speak to cooling hose fixture/manufacturing equipment/change cost, I would bet it's a considerably more expensive change, particularly if engineering thought that another part (water pump?) would need to also be changed as a result. It is possible FCA thought there would be an impact somewhere else in the cooling circuit that would be a more costly change, so they decided to push the countermeasures onto the plastic molded (cheap) parts.

"all done/redesigned for nothing..."
there's always a reason for a design change

"the two physically different...."
Bear in mind that part numbers change if anything is changed. This would include even a 2mm tall rib on the distribution case to change blend door sealing. Don't assume that a part number bump means that some massive change took place. Could be so small you wouldn't even notice if you held the parts in your hand.

"all they needed to do is choke..."
there is more than you realize that goes into issuing an engineering change, and this could affect something else in loop or add process costs we're not aware of, don't know

 

[Jimmy07]

1st, I'll prescribe you a chill-pill.

What I can tell you is changing plastic molded part design is very cheap (relatively). Cannot speak to cooling hose fixture/manufacturing equipment/change cost, I would bet it's a considerably more expensive change, particularly if engineering thought that another part (water pump?) would need to also be changed as a result. It is possible FCA thought there would be an impact somewhere else in the cooling circuit that would be a more costly change, so they decided to push the countermeasures onto the plastic molded (cheap) parts.

The actual cooling system with components is perfectly fine as designed (hoses, water pump, heater core, etc). Let’s attack this from a different direction... Why do you suppose that installing a valve to stop/slow coolant flow through the heater core works as a band aid to get cooler cabin temps?

 

[Streetsweeper]

The actual cooling system with components is perfectly fine (hoses, water pump, heater core, etc). Let’s attack this from a different direction... Why do you suppose that installing a valve to stop/slow coolant flow through the heater core works as a band aid to get cooler cabin temps?

"perfectly fine...."
every part is designed specifically. down to, for example, the flow rate & rpm of the coolant impeller

"Why do you suppose that installing a valve to stop/slow coolant flow through the heater core works as a band aid to get cooler cabin temps?"
Because of the packaging of the HVAC & blend door seal

 

[Jimmy07]

"Why do you suppose that installing a valve to stop/slow coolant flow through the heater core works as a band aid to get cooler cabin temps?"
Because of the packaging of the HVAC & blend door seal

So, there you have it- the ROOT cause was blend door sealing on the HVAC housing, allowing heat from the properly working heater core/coolant system to escape past the blend doors onto the evaporator- hence the reason for a redesigned HVAC box for the TSB. But that was just one root cause of multiple thing taken into account for the auto temp control. There are four duct temp sensors in the distribution box, and one of the sensors was moved, so there wouldn’t be a temperature gap from driver side to passenger side when the target temp is set the same for both sides. Combined with the new HVAC module mapping to control the blend door actuators better, and the way it uses the information from the duct temp sensors, and you have your A/C issue fixed. There was never anything wrong with the way the actual coolant system operates.

 

[hyperx2002]

Munch munch....eating popcorn...

Sent from my SM-G975U using Tapatalk

 

[Streetsweeper]

So, there you have it- the ROOT cause was blend door sealing on the HVAC housing, allowing heat from the properly working heater core/coolant system to escape past the blend doors onto the evaporator- hence the reason for a redesigned HVAC box for the TSB. But that was just one root cause of multiple thing taken into account for the auto temp control. There are four duct temp sensors in the distribution box, and one of the sensors was moved, so there wouldn’t be a temperature gap from driver side to passenger side when the target temp is set the same for both sides. Combined with the new HVAC module mapping to control the blend door actuators better, and the way it uses the information from the duct temp sensors, and you have your A/C issue fixed. There was never anything wrong with the way the actual coolant system operates.

All of these are vehicle level issues (sensors, calibration, etc). The blend door design performed per FCA's spec. Production level hoses raised the outlet temps. Just because FCA chooses to change the HVAC doesn't mean it's the root, it means (99% probably) that it was cheapest to get the vehicle performance where they wanted.

"There was never anything wrong with the way the actual coolant system operates."
Yet FCA issued design changes for sensors & software calibration. Also yes there is, because the system's operation changed when the hoses were swapped. This was also verified on bench test by clamping the hose, resulting in reduced outlet temp.

FCA is responsible for how the hardware performs in the vehicle. The supplier is responsible for proving that the hardware is capable of meeting FCA's performance spec. It doesn't matter if the part is a square, circle, or triangle, so long as it meets spec. If FCA uses the hardware wrong (software calibration, etc), or changes other components (coolant hoses, water pump, etc) that affect the hardware's performance, that is FCA's responsibility and considered a vehicle level issue. It doesn't mean they have to change hoses. They can do whatever they want to make the vehicle performance right. Maybe they want to wrap the dash in heat shield? Expensive but it's up to them.

Your assumption of "they changed the HVAC so the root was the HVAC" is totally incorrect.

The actual cooling system with components is perfectly fine as designed (hoses, water pump, heater core, etc). Let’s attack this from a different direction... Why do you suppose that installing a valve to stop/slow coolant flow through the heater core works as a band aid to get cooler cabin temps?

to revisit this:

"Why do you suppose that installing a valve to stop/slow coolant flow through the heater core works"
Because everything is designed to a spec set by the customer (FCA). So if the spec says to use a flow rate of X, but then changes hoses and now the truck has a flow of Y, the performance changes.

 

[Jimmy07]

All of these are vehicle level issues (sensors, calibration, etc). The blend door design performed per FCA's spec. Production level hoses raised the outlet temps. Just because FCA chooses to change the HVAC doesn't mean it's the root, it means (99% probably) that it was cheapest to get the vehicle performance where they wanted.

"There was never anything wrong with the way the actual coolant system operates."
Yet FCA issued design changes for sensors & software calibration. Also yes there is, because the system's operation changed when the hoses were swapped. This was also verified on bench test by clamping the hose, resulting in reduced outlet temp.

FCA is responsible for how the hardware performs in the vehicle. The supplier is responsible for proving that the hardware is capable of meeting FCA's performance spec. It doesn't matter if the part is a square, circle, or triangle, so long as it meets spec. If FCA uses the hardware wrong (software calibration, etc), or changes other components (coolant hoses, water pump, etc) that affect the hardware's performance, that is FCA's responsibility and considered a vehicle level issue. It doesn't mean they have to change hoses. They can do whatever they want to make the vehicle performance right. Maybe they want to wrap the dash in heat shield? Expensive but it's up to them.

Your assumption of "they changed the HVAC so the root was the HVAC" is totally incorrect.


to revisit this:

"Why do you suppose that installing a valve to stop/slow coolant flow through the heater core works"
Because everything is designed to a spec set by the customer (FCA). So if the spec says to use a flow rate of X, but then changes hoses and now the truck has a flow of Y, the performance changes.

Ok, last thing I’ll say on this subject, then I’ll leave you to it with the speculation.
You got the engine cooling system that has a water pump, radiator, thermostat, some hoses, and a heater core, which is only used to heat the cab. Doesn’t get much simpler than that, and there was never an issue with that system. Then, you have the HVAC system, and at it’s core is the HVAC module, which, among other things, controls the movement of the blend doors. This has always been how Ram has throttled the heat from entering the HVAC housing and reaching the evaporator for when maximum cabin cooling is desired. While there are vehicle manufacturers that use a motorized valve controlled by the HVAC module to meter the coolant going through the heater core in their A/C systems, Ram is not one of them. In fact, FCA has never used a system like that on any of their vehicles as far as I can remember. Is one system better than the other? That’s a whole other debate. But, why on earth, if FCA has never implemented a system like that, would they try to introduce a valve in the coolant system as a fix, or even worse, as you suggest, reduce the heater hose diameter constricting flow of coolant to the heater core?!? How would you open the flow back up in the winter time when maximum heat is needed in the cab?
Bottom line is- people can choose to hack in a valve that you have to operate depending on weather, step down the heater hose size like you suggest (and then what?), or....just have the TSB performed where you get a new HVAC box, distribution housing, and HVAC module.

 

[Streetsweeper]

Ok, last thing I’ll say on this subject, then I’ll leave you to it with the speculation.
You got the engine cooling system that has a water pump, radiator, thermostat, some hoses, and a heater core, which is only used to heat the cab. Doesn’t get much simpler than that, and there was never an issue with that system. Then, you have the HVAC system, and at it’s core is the HVAC module, which, among other things, controls the movement of the blend doors. This has always been how Ram has throttled the heat from entering the HVAC housing and reaching the evaporator for when maximum cabin cooling is desired. While there are vehicle manufacturers that use a motorized valve controlled by the HVAC module to meter the coolant going through the heater core in their A/C systems, Ram is not one of them. In fact, FCA has never used a system like that on any of their vehicles as far as I can remember. Is one system better than the other? That’s a whole other debate. But, why on earth, if FCA has never implemented a system like that, would they try to introduce a valve in the coolant system as a fix, or even worse, as you suggest, reduce the heater hose diameter constricting flow of coolant to the heater core?!? How would you open the flow back up in the winter time when maximum heat is needed in the cab?
Bottom line is- people can choose to hack in a valve that you have to operate depending on weather, step down the heater hose size like you suggest (and then what?), or....just have the TSB performed where you get a new HVAC box, distribution housing, and HVAC module.

There is no speculation. You just don't know what you're talking about. I can tell you either aren't in vehicle design engineering or don't understand how the business works. It really is simple but as it seems so are you.

Here's my last explanation of how the engineering works between a tier 1 supplier and the OEM, with an example of your misunderstanding:

1. FCA approaches supplier with a spec: "here's how it must perform and here are the inputs" (coolant, hose size, hose length...are inputs)
2. Supplier designs the HVAC, inputs per FCA's specification, and provides a report to FCA
3. FCA reviews the report & says "ok your HVAC performs how we require it to. all good to proceed."
4. FCA changes hose size, changes performance of HVAC prior to mass production
5. Vehicle cooling performance is changed as a result of #4
6. FCA engineers: "shoot we have a cooling performance problem. How do we countermeasure it thru design change? The hoses we changed? HVAC? What's cheapest?"
7. FCA engineers do some testing and discover if they change the HVAC, some sensors, calibration, etc (whatever parts, its just an example) then the outlet temp is fixed
8. FCA approaches supplier because every OEM always tries to blame the supplier first so that maybe they're stupid enough to pay for the engineering change
9. Supplier sends them the signed report: "No, sorry. We met per your spec, here's your signatures. Everything is performing exactly how it should per your spec. You changed the vehicle."
10. FCA engineers: "supplier is right. what change is cheapest?.......molded plastic parts"
11. FCA asks HVAC supplier to quote changes X, Y, or Z & a price is eventually agreed upon (FCA is paying)
12. FCA coordinates a change between the HVAC, duct, sensor, control head (calibration), and any other relevant supplier
13. all of the involved suppliers deliver new parts on the implementation date for mass production at a build date determined by the supplier lead times & FCA's decision on 'when'

How your brain is working:

"oh shoot FCA lit a fire in the HVAC!! Why isn't the HVAC putting the fire out?! Bad HVAC design!!" (the fire isn't supposed to be there & also isn't on FCAs spec)

Just because an OEM chooses to change a component to resolve a vehicle level issue, does not mean that component is the cause of the vehicle issue. It almost always means changing that component is cheapest to fix whatever the vehicle's symptoms are. This is how automobile manufacturing works.

 

[Streetsweeper]

"or even worse, as you suggest, reduce the heater hose diameter constricting flow"
The flow rate is too high currently. There is literally nothing wrong with reduce hose diameter. It's how the HVAC was validated. It now has too much flow. Holy sh*t why don't you understand.

"How would you open the flow back up in the winter time"
I didn't say the valve hack was right. The right move is for FCA to correct the vehicle performance for the paying customers. Whatever that fix is, is up to FCA.

You are thicker than the Puerto Rican girls in Tampa.

 

[brian42]

All that matters to me is that FCA acknowledged an issue and did something to change it and make it better for those of us who have the problem.

All I care about is that my A/C is colder. Whether that's through heater hose diameter, plastic parts, or an engine swap I don't care.

Now I just have to get the dealership service department to buy off on the repair when the weather warms back up.

 

[Streetsweeper]

All that matters to me is that FCA acknowledged an issue and did something to change it and make it better for those of us who have the problem.

All I care about is that my A/C is colder. Whether that's through heater hose diameter, plastic parts, or an engine swap I don't care.

Now I just have to get the dealership service department to buy off on the repair when the weather warms back up.

"Whether that's through heater hose diameter, plastic parts, or an engine swap I don't care."
Yes. This is decided by the business case that has least profit impact.

 

[Jimmy07]

All that matters to me is that FCA acknowledged an issue and did something to change it and make it better for those of us who have the problem.

All I care about is that my A/C is colder. Whether that's through heater hose diameter, plastic parts, or an engine swap I don't care.

Now I just have to get the dealership service department to buy off on the repair when the weather warms back up.

Yup, that’s all that matters is that the fix works.
But hey, thank god they randomly decided out of the blue to change the heater hose specs for no reason (on only the 5th gen 1500s and HD Rams to boot). Otherwise they probably never would have discovered that the HVAC box had a design flaw where the blend doors couldn’t create a seal against the box, or the HVAC module was reading the info from the temp sensors incorrectly (discovered due to extensive data logging performed by another member on the HD forum).

 

[Scap]

FYI Ford's have the highest cooling capacity so look at F150s.
GM likes to source the absolute cheapest supplier so I can't make any comment as I steer clear. Could be fine.

my 13 F-150 _never_ blew cold. Maybe it was an 11-14 model specific issue as others don't seem to complain the way we did. If this truck blows half as bad as my Ford, I'll be tickled pink.

 

[Streetsweeper]

my 13 F-150 _never_ blew cold. Maybe it was an 11-14 model specific issue as others don't seem to complain the way we did. If this truck blows half as bad as my Ford, I'll be tickled pink.

Every vehicle can have issues. I can only tell you that Ford is the most obsessed with airflow volume compared to the other 2.

 

[Streetsweeper]

Yup, that’s all that matters is that the fix works.
But hey, to change the heater hose specs for no reason (on only the 5th gen 1500s and HD Rams to boot). Otherwise they probably never would have discovered that the HVAC box had a design flaw where the blend doors couldn’t create a seal against the box, or the HVAC module was reading the info from the temp sensors incorrectly (discovered due to extensive data logging performed by another member on the HD forum).

"thank god they randomly decided out of the blue"
As I said, every engineering change happens for a specific reason. You really have no appreciation for or understanding of how much coordination it takes from different engineering teams to all work separately but have all of their parts come together, fit, and function as cars roll off an assy line. Perhaps engine team didn't talk to climate. Perhaps integration team didn't think anything of it. Who knows.

I can only say without a doubt that the root cause is the hose. The countermeasure, doesn't necessarily have to be at the hose. Clearly it isn't.

 

[taz2016]

I generally have no interest in participating in internet squabbles. I also do not claim to be an automotive engineer or to have "worked ~50ft from where the HVAC was designed", but I do have a simple question for Streetsweeper. Do you really think it is cheaper for FCA to do the repair they are using than to engineer a simple to install restricted hose replacement?