Air conditioning performance

[KcRay]

Sorry if this was already addressed somewhere, there's a lot of AC threads with a lot of pages.

When first getting in my truck and I switch from the Max AC setting to the Auto AC setting the fan actually blows quite a bit harder/ louder than it does on Max AC.

My understanding is the Max AC setting should give you the coldest/ lowest temperature setting with the highest fan setting. The Max AC setting it shows fan speed "7" and in my truck there is no higher fan setting so how does the fan go higher when I switch to Auto?

Does anyone else's truck do this?

Same here, seems like there's a number 8 fan speed in auto mode.

 

[RBRK]

My A/ C has been pretty good since I’ve had the pcm flashes and HVAC update that may or probably didn’t do much. Anyway I decided to swing by the local harbor freight and put a clamp on the heater hose. Drove home with a digital temp gauge in the vents. I actually was blowing 39.7 out of the passenger vent in a short time. I put it on in the parking lot and drove about 10 minutes home. This was on max a/c. Auto rose the blower speed like usual and it went up 2-3 degrees. It’s 98 degrees on the dash and it’s blowing 39.7 passenger and 42 out of the drivers. Pretty impressive. I got home took the clamp off and held the RPM to 1500 and it was blowing 47.6 drivers side. I know it’s been posted before but I just was giving my results. The clamp or valve obviously helps. When it’s 90 here mine seems great. It’s just been super hot and I was curious to see my results. Last year my truck was blowing 60 drivers side and never cooled down.

If FCA was smart they would put in an electronic valve and a sub harness that hooks into the factory wiring so it would close when Max A/C is desired. It could be that the blend door isn’t sealing when closed like if there is foam on the door it could be an issue or even the door is too small causing a bleed through loss around the door. I don’t see an easy fix for this. I hope I’m wrong.

 

[ramhead]

My A/ C has been pretty good since I’ve had the pcm flashes and HVAC update that may or probably didn’t do much. Anyway I decided to swing by the local harbor freight and put a clamp on the heater hose. Drove home with a digital temp gauge in the vents. I actually was blowing 39.7 out of the passenger vent in a short time. I put it on in the parking lot and drove about 10 minutes home. This was on max a/c. Auto rose the blower speed like usual and it went up 2-3 degrees. It’s 98 degrees on the dash and it’s blowing 39.7 passenger and 42 out of the drivers. Pretty impressive. I got home took the clamp off and held the RPM to 1500 and it was blowing 47.6 drivers side. I know it’s been posted before but I just was giving my results. The clamp or valve obviously helps. When it’s 90 here mine seems great. It’s just been super hot and I was curious to see my results. Last year my truck was blowing 60 drivers side and never cooled down.

If FCA was smart they would put in an electronic valve and a sub harness that hooks into the factory wiring so it would close when Max A/C is desired. It could be that the blend door isn’t sealing when closed like if there is foam on the door it could be an issue or even the door is too small causing a bleed through loss around the door. I don’t see an easy fix for this. I hope I’m wrong.

Good to know...I'm like you...getting around 47 out the driver's vent with no modifications. I think that's probably good enough and will give more than acceptable cooling performance for me but if I ever need to, I can clamp down the hose for ultimate cooling.

 

[ac1dd]

Wait? What? - I would think keeping the rear ones closed would boost front vent performance and give lower temps since the cooling system wasn't "driving" every vent in the truck. My recent test I just did was with rear vents closed....guess I'll open them and test that too.

Wow now that doesn't make logical sense. Anyone else elaborate on this aspect of things. I too would think that
closing the rear vents would boost CFM pressure for the air coming out of the front vents.

 

[ac1dd]

Good to know...I'm like you...getting around 47 out the driver's vent with no modifications. I think that's probably good enough and will give more than acceptable cooling performance for me but if I ever need to, I can clamp down the hose for ultimate cooling.

What was your ambient temp outdoors? Thanks.

 

[SpeedyV]

Wow now that doesn't make logical sense. Anyone else elaborate on this aspect of things. I too would think that
closing the rear vents would boost CFM pressure for the air coming out of the front vents.

Off the top of my head, (1) closing vents might raise velocity in remaining open vents to a level of turbulence, resulting in louder but less efficient airflow delivery, and (2) cool the cabin unevenly, leading to hotspots and perhaps never fully cooling the cabin. But I’m just spitballing.

 

[ramhead]

What was your ambient temp outdoors? Thanks.

Info was upthread but it was 73 degrees and 80% humidity. We had a heat wave over the weekend with temps near 100 and truck felt perfect inside but I did not check until today.....supposed to be near 90+ by this weekend so I'll recheck.

 

[Gman]

Wow now that doesn't make logical sense. Anyone else elaborate on this aspect of things. I too would think that
closing the rear vents would boost CFM pressure for the air coming out of the front vents.

It's like trying to cool your entire house with half the registers closed. Volume counts, not "pressure".

 

[moosem]

 

[Gman]

View attachment 31718

I saw it flinch. Apparently there's still some life left in it.

 

[ramhead]

It's like trying to cool your entire house with half the registers closed. Volume counts, not "pressure".

Ok......but, we're not attempting to get a whole cabin temperature...for the most part all of the tests done here have been for temps at/inside the vents. An overall cabin reading/test would also be interesting and I can see that all vents should be open for that....but not having the rears open for a specific front vent test should only help (or at least not affect) a temp reading at those front vents.

 

[ramhead]

View attachment 31718

 

[Gman]

Ok......but, we're not attempting to get a whole cabin temperature...for the most part all of the tests done here have been for temps at/inside the vents. An overall cabin reading/test would also be interesting and I can see that for that all vents should be open....but not having the rears open for a specific front vent test should only help (or at least not affect) a temp reading at those vents.

That depends on what your intended goal is. If you're only concerned about the temperature coming out of the vents, sure. If you actually care about the internal cabin temp, then you're only testing one piece of the entire puzzle. If you're looking at an equivalent volume of air, with the same circulation patterns, then the temperature is relative.

In other words, if the AC can't cool the volume of the cab, no matter how low the temp is coming from the vents, then the system is inadequate. If you're disabling parts of the system to get a front vent temp result, then I find it difficult to then conclude that the system is deficient.

I have experienced a notable difference in the cooling ability at idle with the fan vs. driving the truck. I wonder if there's something that FCA can change to improve function at idle, or if it's a limitation in the cooling area of the condenser affected by the round fan vs. the entire rectangular area cooled as the truck moves forward.

 

[DraKhen99]

Off the top of my head, (1) closing vents might raise velocity in remaining open vents to a level of turbulence, resulting in louder but less efficient airflow delivery, and (2) cool the cabin unevenly, leading to hotspots and perhaps never fully cooling the cabin. But I’m just spitballing.

This logic makes sense, especially if you're sitting in a heat-soaked truck. If the air is moving slower through the dash vents, it's picking up the heat energy from the hot dash parts, and thus would exit the dash vents at a higher temperature.

Has anyone taken apart a new DT dash to see what the ducts look like? Perhaps some sort of insulation could be added to the duct work to make exit temps lower?

-John

 

[Snoopy321]

First full disclosure. I don’t own a Ram but was considering buying one. However since I live in the gulf south an a strong A/C is a must I’m not sure that will happen.

From what Inread here it seems the new Ram’s A/C capacity is not enough. Apparently the refrigerant charge is just 1.12 lbs. My 2016 Ford’s charge is 1.93 lbs of R-134a, almost a full pound more. Ironically when I checked my old Honda it’s capacity is 1.1 lbs and it’s cabin is way smaller than a crew cab truck. There is no fix for a system that is undersized for its application.

It can’t be the new refrigerant because Ford and GM both use it on their current trucks and there aren’t any complaints about them. As a matter of fact I had a 2018 F-150 loaner and it got just as cold as my R-134a truck. Also the previous gen Ram used it and it was fine.

I believe since the new Ram was developed under Fiat ownership their European background and cooler climate caused them to underestimate how hot it can get in the U.S. The new Ram may be fine for a hot 80 degree day in Italy but it’s underpowered for a hot humid day in Houston Texas. Their performance data shows that they find a 55 degree vent temperature at 95 degrees ambient to be within specifications.

 

[moosem]

First full disclosure. I don’t own a Ram but was considering buying one. However since I live in the gulf south an a strong A/C is a must I’m not sure that will happen.

From what Inread here it seems the new Ram’s A/C capacity is not enough. Apparently the refrigerant charge is just 1.12 lbs. My 2016 Ford’s charge is 1.93 lbs of R-134a, almost a full pound more. Ironically when I checked my old Honda it’s capacity is 1.1 lbs and it’s cabin is way smaller than a crew cab truck. There is no fix for a system that is undersized for its application.

It can’t be the new refrigerant because Ford and GM both use it on their current trucks and there aren’t any complaints about them. As a matter of fact I had a 2018 F-150 loaner and it got just as cold as my R-134a truck. Also the previous gen Ram used it and it was fine.

I believe since the new Ram was developed under Fiat ownership their European background and cooler climate caused them to underestimate how hot it can get in the U.S. The new Ram may be fine for a hot 80 degree day in Italy but it’s underpowered for a hot humid day in Houston Texas. Their performance data shows that they find a 55 degree vent temperature at 95 degrees ambient to be within specifications.

Yeah, that’s it. It never occurred to them that it gets hot in Houston. Now it all makes sense!

BTW - it also gets very hot In Italy

 

[SpeedyV]

First full disclosure. I don’t own a Ram but was considering buying one. However since I live in the gulf south an a strong A/C is a must I’m not sure that will happen.

From what Inread here it seems the new Ram’s A/C capacity is not enough. Apparently the refrigerant charge is just 1.12 lbs. My 2016 Ford’s charge is 1.93 lbs of R-134a, almost a full pound more. Ironically when I checked my old Honda it’s capacity is 1.1 lbs and it’s cabin is way smaller than a crew cab truck. There is no fix for a system that is undersized for its application.

It can’t be the new refrigerant because Ford and GM both use it on their current trucks and there aren’t any complaints about them. As a matter of fact I had a 2018 F-150 loaner and it got just as cold as my R-134a truck. Also the previous gen Ram used it and it was fine.

I believe since the new Ram was developed under Fiat ownership their European background and cooler climate caused them to underestimate how hot it can get in the U.S. The new Ram may be fine for a hot 80 degree day in Italy but it’s underpowered for a hot humid day in Houston Texas. Their performance data shows that they find a 55 degree vent temperature at 95 degrees ambient to be within specifications.

There are incorrect assumptions here; the new Ram 1500 is advertised to provide more airflow volume than any previous system. It is very unlikely to be undersized. Here’s FCA’s quote:

“The new HVAC system features nearly 25 percent more air flow at lower noise levels, including larger front defroster vents for better performance. Improved vents give rear passengers 50 percent more airflow when compared to the previous generation.”

There have been quite a few posts discussing the actual problem (blend door actuation and/or programming); surf back through previous threads to learn more.

 

[ColoradoCub]

First full disclosure. I don’t own a Ram but was considering buying one. However since I live in the gulf south an a strong A/C is a must I’m not sure that will happen.

From what Inread here it seems the new Ram’s A/C capacity is not enough. Apparently the refrigerant charge is just 1.12 lbs. My 2016 Ford’s charge is 1.93 lbs of R-134a, almost a full pound more. Ironically when I checked my old Honda it’s capacity is 1.1 lbs and it’s cabin is way smaller than a crew cab truck. There is no fix for a system that is undersized for its application.

It can’t be the new refrigerant because Ford and GM both use it on their current trucks and there aren’t any complaints about them. As a matter of fact I had a 2018 F-150 loaner and it got just as cold as my R-134a truck. Also the previous gen Ram used it and it was fine.

I believe since the new Ram was developed under Fiat ownership their European background and cooler climate caused them to underestimate how hot it can get in the U.S. The new Ram may be fine for a hot 80 degree day in Italy but it’s underpowered for a hot humid day in Houston Texas. Their performance data shows that they find a 55 degree vent temperature at 95 degrees ambient to be within specifications.

It’s got nothing to do with the Freon snoopy, bypassing the heater core gives me plenty cold AC in 100 deg temps. It’s a blend door issue in the hvac box

 

[Edwards]

Just got mine back and they flashed the FW with numbers I've not seen before. WO states, "Flashing from current part number 68277068AG to targeted part number 68277068AI. A/C is now blowing as intended."

It blew comfortably cold on the way home. I'll break out the thermometer to see if this affects the blend door at all.

 

[Gman]

The amount of freon for a charge is largely determined by the overall volume of the system. This includes how much plumbing it takes to route the coolant and the size of the evaporator and condenser. You can't compare the weight of the freon between *insert vehicle here* and expect it to mean anything.