A/C Performance

[llando88]

Just wanted to post and say how glad I am to find this info, and appreciate all the posts made by everyone here. It's great info.

The A/C on my '21 Ram 1500 has been struggling lately to keep up with the Florida heat. I put a thermometer on the center vent and it would not go below 52F (ambient 86F.) Which I thought was a bit high compared to my previous car.

I went to my local Ram dealer Monday to talk to them. The Service Writer told me they would not look at the truck unless it was blowing 75F or above. Uh, ok. So I left. My guess is the dealership didn't want to bother with the truck (they told me they "could not look at it today" and that I'd have to leave it.) I also believe I'd be looking at paying a diagnostic, because it sure sounded like they just did not want to deal with it, since it is probably a well-known issue.

I then did some research and stumbled onto this thread. Wow! I had no idea these trucks had such an ongoing issue with tepid A/C performance, but now I understand a lot more.

Looking at what I could do to improve this, I realized I had installed a Bosch 6090C HEPA cabin air filter back in May. Based on input here and elsewhere, this is probably cutting down my airflow, so I am going to remove that and install a K&N VF2065. As soon as I decide how it fits (there's no "flow" arrow, and there is this weird "curve" shaped to one side) I'll put it in the truck. I'll also try that "exercise the blend door" trick, mentioned up thread. I will also look into the hose hack, that sounds genius.

Otherwise I'm pretty happy with the truck; we bought it to tow a mid-size travel trailer, which it does well. We sold the trailer earlier this year, but I'm still happy driving it, and don't have any immediate plans to sell it, since it's paid for and all.

 

[theblet]

I just received the k&n yesterday and installed it. No air flow arrow on it. Installed the strange “u” shape toward the access door. The instructions are vague.

I will see how the air flow is with this one, but at first glance it doesn’t seem to be much stronger compared with my cheap carbon one.

 

[seansmd]

Bought the k$n but worry it is too big for the 2023, has anyone put one in?

Have winco 10 on the rears, 20 on the fronts, and 55 on the windshield going on today.

 

[Brutal_HO]

Couple guys on the hdrams forum are working on a hack for the evap temp sensor.

AC Fix TSB (Pre 8/20 build trucks)

hdrams.com

When they get the final resistance value figured out, I recommended they use a multiturn Bournes trimmer resistor.

Seems to me RAM has some calibration issue with their sensors and software - as well as the HVAC box/evap/blend door problem. I had the TSB completed on my 2020 3500 and the A/C is much improved but still not 100%.

 

[seansmd]

Ceramic tint outcome.

 

[theblet]

Couple guys on the hdrams forum are working on a hack for the evap temp sensor.

AC Fix TSB (Pre 8/20 build trucks)

hdrams.com

When they get the final resistance value figured out, I recommended they use a multiturn Bournes trimmer resistor.

Seems to me RAM has some calibration issue with their sensors and software - as well as the HVAC box/evap/blend door problem. I had the TSB completed on my 2020 3500 and the A/C is much improved but still not 100%.

This is very interesting. Curious to see how it turns out. Where is that sensor located?

Also, the k&n filter didn’t really help air flow. I may just clean the exiting oil off the filter and not reapply to see if that helps.

 

[Brutal_HO]

This is very interesting. Curious to see how it turns out. Where is that sensor located?

Also, the k&n filter didn’t really help air flow. I may just clean the exiting oil off the filter and not reapply to see if that helps.

Not sure exactly, but it's in one of the posts. Sounds like a few hours to R&R the glove box and other parts needed to access it.

That said, it could be entirely different in the 5th gen trucks.

 

[c3k]

This is very interesting. Curious to see how it turns out. Where is that sensor located?

Also, the k&n filter didn’t really help air flow. I may just clean the exiting oil off the filter and not reapply to see if that helps.

This looks VERY promising.

I cannot imagine that RAM would have a significant difference in design. If the HD trucks use an evap temp sensor, so too should ours. Adding a resistor in parallel to create an artificially hot sensor temp to fool the compressor...is a simple solution to putting colder air, longer, into the truck.

****

Edit: Part number is Mopar 68396045AA. Same as HD trucks.
From the linked HD forum thread:
With the sensor in an ice bath it wwas reading about 8.5Kohms.
Sitting in ambient air, 20*Cish it was around 3.5Kohm
The colder the sensor gets, the higher the resistance value. To lower the resistance value will send bias the signal to show a warmer temperature.

The part is ~$15 and seems to sit just above the fan assembly in the airbox. (Hard to tell on the parts diagrams.)

****

2nd Edit: Mouser has a variable resistor, here: https://www.mouser.com/ProductDetail/Bourns/3296W-1-303LF?qs=1G4X78fplldRd8Pf3DvnTA==

There are other varieties. Being able to twist the screw to adjust the resistance value would allow tweaking the air conditioner output after installing this...if the screw is able to be accessed. (Glue the resistor under the dash? Run the leads back to the evap sensor.)

 

[llando88]

Looking at what I could do to improve this, I realized I had installed a Bosch 6090C HEPA cabin air filter back in May. Based on input here and elsewhere, this is probably cutting down my airflow, so I am going to remove that and install a K&N VF2065. As soon as I decide how it fits (there's no "flow" arrow, and there is this weird "curve" shaped to one side) I'll put it in the truck. I'll also try that "exercise the blend door" trick, mentioned up thread. I will also look into the hose hack, that sounds genius.

After a day of driving with the K&N cabin filter vs. HEPA: Mrs. commented that the truck had "more air" on her side through the vents. I thought the A/C had more oomph, but wasn't sure if I was imagining it.

Today on a longer run, I saw temp out of the center vent down to 49, so that at least is an improvement of 3 degrees. On the other hand, we had an overcast day, not full sun, so I was driving in 90 instead of 96. Perhaps it's colder now, perhaps not. IDK.

I'll keep monitoring the system and will let ya'll know if I see anything significant. But at the moment, I am glad to have the new filter. Even if it just results in more air flow through the system, it was money well spent.

 

[theblet]

After a day of driving with the K&N cabin filter vs. HEPA: Mrs. commented that the truck had "more air" on her side through the vents. I thought the A/C had more oomph, but wasn't sure if I was imagining it.

Today on a longer run, I saw temp out of the center vent down to 49, so that at least is an improvement of 3 degrees. On the other hand, we had an overcast day, not full sun, so I was driving in 90 instead of 96. Perhaps it's colder now, perhaps not. IDK.

I'll keep monitoring the system and will let ya'll know if I see anything significant. But at the moment, I am glad to have the new filter. Even if it just results in more air flow through the system, it was money well spent.

I would think the K&N would flow more than a hepa filter, but maybe not a regular wide pleated one.

 

[BowDown]

Thank you. I em pretty sure the filter is right above the blower motor. Like you said, all air is passed through it.

I’d like to find a less restrictive filter to use. The one I have now is a basic charcoal one, not hepa or anything. The only other one i see is maybe the K&N one. It looks like you can see daylight through it so that may be a better option. I wish I could get one that was just a screen.

View attachment 163406

I have the K&N version and have had it for about a year, washed it twice so far. I'll have to try your test on it and see if there's a difference with it.
That said, I have the latest AC TSB done and mine blows effin cold, I cant run mine on recirculate above speed 5 more than about 15 min after the trucks been sitting in the hot Texas heat. Today it was 105, I had to turn the AC down to 4 and turn recirculate off and it was still damn cold

 

[HSKR R/T]

I have the K&N version and have had it for about a year, washed it twice so far. I'll have to try your test on it and see if there's a difference with it.
That said, I have the latest AC TSB done and mine blows effin cold, I cant run mine on recirculate above speed 5 more than about 15 min after the trucks been sitting in the hot Texas heat. Today it was 105, I had to turn the AC down to 4 and turn recirculate off and it was still damn cold

Why not just set it to "auto" and set your desired temperature?

 

[BowDown]

Why not just set it to "auto" and set your desired temperature?

I like to be cold

 

[BowDown]

This is very interesting. Curious to see how it turns out. Where is that sensor located?

Also, the k&n filter didn’t really help air flow. I may just clean the exiting oil off the filter and not reapply to see if that helps.

That's interesting, be nice if someone posted pics of what they did

 

[theblet]

That's interesting, be nice if someone posted pics of what they did

Ikr. Maybe once they’ve completely figured it out

 

[Vulpes]

Me too, <sigh>. 2019 Rebel here, bought the truck awhile back with 36K miles on it, and could tell immediately it was not cooling the cabin as well as my 2003 Dakota. The Rebel AC really struggles with two people and two dogs in hot climates. AND my spouse gets to take the pizzz, about how effing cold their Subaru gets...

Checked it with a thermometer and installed the "hack" last night, which is installing a valve to stop hot water from going to the heater core:

	Before hack	After hack
Ambient temperature around 95 deg F. Readings at center vent, left side. Recirculating on, max cold, max fan speed.	50-55 deg F	41-44 deg F

I'll probably install HVAC TSB 24-001-20, see where that gets me.

I might have a real nice truck someday, after fixing all the issues with it.

 

[theblet]

Me too, <sigh>. 2019 Rebel here, bought the truck awhile back with 36K miles on it, and could tell immediately it was not cooling the cabin as well as my 2003 Dakota. The Rebel AC really struggles with two people and two dogs in hot climates. AND my spouse gets to take the pizzz, about how effing cold their Subaru gets...

Checked it with a thermometer and installed the "hack" last night, which is installing a valve to stop hot water from going to the heater core:

	Before hack	After hack
Ambient temperature around 95 deg F. Readings at center vent, left side. Recirculating on, max cold, max fan speed.	50-55 deg F	41-44 deg F

I'll probably install HVAC TSB 24-001-20, see where that gets me.

I might have a real nice truck someday, after fixing all the issues with it.

The TSB makes a world of difference. There's literally no temp difference now with my hack opened or closed. Just sucks that you have to pay for it. Maybe try to get a good will repair from ramcares since it’s a design flaw and not just a failed part.

 

[seansmd]

The TSB makes a world of difference. There's literally no temp difference now with my hack opened or closed. Just sucks that you have to pay for it. Maybe try to get a good will repair from ramcares since it’s a design flaw and not just a failed part.

What is the tsb, and how much do they charge?

 

[HSKR R/T]

What is the tsb, and how much do they charge?

If you are under warranty, and it's the actual issues it doesn't cost anything

 

[theblet]

What is the tsb, and how much do they charge?

Using the TSB, the dealer will follow the procedure to change out your HVAC housing to a new design, in which the heater core air doesn’t mix with the evap core air. Here is the TSB for you to reference. Not sure how much they charge, but I think it is over $1000 iirc.