Air conditioning Hack

[User_3336]

I went on a 130 round trip today. It was 95 outside today. Not sure what the humidity was. With my "clamps" in place, I maintained a 42 degree vent temp, max a/c setting 7. Several times I had to literally (1) turn it off, and still recirculate, (2) vent and floor. the cab cooled down fairly quick after setting in the sun a hour at the destination.

I am NOT a fan of "remote start" to cool down the cabin before I get in. I will roll all the windows down for about a mile, letting a lot of that heat escape from the cab. Then I'll turn the a/c on 7 with the windows still down for a minute or two, then UP, and begin the cooling. After I feel its "cool" to me, I'll recirculate.

I'm telling you, this "clamping" idea works like a charm!

 

[Cal3600]

Man this whole A/C thing was almost a deal breaker for me when looking into the Ram. I keep my house at 67 all summer in TX, so clearly I'm not a fan of the heat. My black Limited with black interior diesel seems fine though. Today I measured 44 at the vent with 96 temps outside, no hack.

 

[FYRSTIX]

I thought the rear power sliding window was a cute novelty, but I wouldn't use it much. Wrong! Along with the front windpws, opening it really helps with moving the hot, stale air out of the cab quickly.

 

[slicktop]

I thought the rear power sliding window was a cute novelty, but I wouldn't use it much. Wrong! Along with the front windpws, opening it really helps with moving the hot, stale air out of the cab quickly.

Yes! I thought it was a cute Idea and maybe I'd use it once a year, but I use it darn near every time I get in the truck!

 

[392DCGC]

This part is nonsense, at least for our trucks. Recirc simply means you're taking already conditioned air and blowing it back over the coil; not having recirc on means you're trying to condition 100 degree air for the first time, every time. The only thing that changes is the source of the air being cooled; it does not reduce flow to the back seat. In fact, I don't know of any vehicle that I've ever owned or driven in which having recirc on reduced the airflow to any portion of the cabin. Actually, I've found the opposite to be true; you can test this yourself by turning recirc off and back on. You'll notice the system is louder in recirc mode, which is a byproduct of more air moving through the system. Hold the back of your palm up to the vent and you'll likely notice it blowing harder in recirc mode as well.

Your post is completely incorrect. Recirc can reduce airflow to the rear. How? Because when the HVAC is pulling air from the outside and blowing most of it from the front of the cab, it’s consequently pushing air back outside at the rear cab vents of the truck. It has to do this otherwise the cabin would attempt to pressurize and airflow would stop. Air naturally flows from the front to the rear of the cab, which helps equalize the temps throughout.

Recirc gets louder because it is sucking a lot of air through a small opening below the glove box - forced airflow is noisy. If anything, it could be moving less air because the recirc path is likely more restrictive.

Yeah there is a reason "max ac" button in our trucks turns on the recirc function.

It turns on recirc because HVAC systems cause temperature delta change. e.g. AC system might only change the air temp by 40 degrees. Re-cooling the same air over and over is easier than constantly cooling 100 degree air.

Yeah partial clamping or cracking the valve defeats the purpose, you will still have 200+ deg coolant going to the core and blending with your cold air. That’s what makes it so easy to understand what the flaw is in these trucks AC system..

No it doesn’t. If you cut off flow completely, you have stagnant coolant in your core and lines for months. Sounds like a bad idea. Also, you lose all heat functionality. Weather isn’t constant. Cool summer nights happen, and maintaining HVAC function requires some heat. You can greatly reduce the flow and still get better AC temps without completely cutting off the flow.

I am NOT a fan of "remote start" to cool down the cabin before I get in. I will roll all the windows down for about a mile, letting a lot of that heat escape from the cab.

Remote start or remote window-down is still valuable. You can drive off and flush out hot air all you want, but it takes time to cool down that 150 degree interior. It will keep radiating heat long after you have flushed out that initial superheated air.

 

[Timeless]

I am NOT a fan of "remote start" to cool down the cabin before I get in.

Curious as to why? Is it you don't want to waste fuel? Worried about theft?

 

[User_3336]

Because it seems ineffective. that's alot of HOT cabin to cool down at first. Rolling down the windows first and letting some of that heat escape seems a little more efficient.

To each his own.

Curious as to why? Is it you don't want to waste fuel? Worried about theft?

 

[slicktop]

Your post is completely incorrect. Recirc can reduce airflow to the rear. How? Because when the HVAC is pulling air from the outside and blowing most of it from the front of the cab, it’s consequently pushing air back outside at the rear cab vents of the truck. It has to do this otherwise the cabin would attempt to pressurize and airflow would stop. Air naturally flows from the front to the rear of the cab, which helps equalize the temps throughout.

Recirc gets louder because it is sucking a lot of air through a small opening below the glove box - forced airflow is noisy. If anything, it could be moving less air because the recirc path is likely more restrictive.

Sorry, but no. You're just way off. If I get bored someday I'll get an anenomometer out of the office and do a mini air flow test to show you how you're totally wrong, but it shouldn't even be necessary. I just double checked and you can, too. Sit in the drivers seat with the AC on full cool, full fan, on recirc. Put one palm in front of a front vent and the other in front of a rear vent. Feel the air. Now turn off the recirc and put your palms back in the same place. The air both gets warmer and reduces in velocity. In no way does that aide cooling. I'm well aware of over pressurization conditions and friction loss in HVAC systems as my company engineers, tests, and commissions HVAC systems, but those factors clearly don't play a part in these trucks, as is evidenced by the lay test I described above. Now, I will admit that you could be right about one thing; the louder air on recirc *could* be a consequence of a smaller opening, that is a possibility. However, the main point is that in no way is slower, warmer air going to cool the back seat down quicker, sorry.

 

[slicktop]

Yesterday I decided to buy a digital thermometer to test my AC. It was 75 outside and I was able to get 54 out of the drive side vents, but the passenger vent got down to 46(!!). The 46 felts great, I only wish my other vents would do the same. If I can do the hack and drop them down to 45/40 I’d be happy. Still waiting to see what the new part is the ramcares mentioned they were making.

I can't find mention of this new part.... could you point me in the right direction, please? Thanks!

 

[z0n3]

I can't find mention of this new part.... could you point me in the right direction, please? Thanks!

Post # 678

A/C Performance

Maybe it's time to stop buying RAM's :unsure: if it weren’t such an easy fix I would, but I love everything else about the truck compared to the alternatives.

5thgenrams.com

 

[slicktop]

Just drove around the neighborhood for fun. Here's the reading out of the drivers side front vent, left of the radio, with the air on full cool, full fan, recirc on:

That's a bit below 38, so can we call that 37? Now here's the same vent, same fan speed, same cool setting, nothing changed except recirc off, taken only one minute after turning off recirc:



That's what, 55, 56 degrees? I'd love to hear how an extra 18 degrees could possibly cool the cabin quicker. Here's the back vent, recirc on:

Sorry, selfie camera flipped image, but can we agree on 40 degrees? Now here's the same vent with recirc off, again, just one minute later:


That's again another, what, 16 degrees? I don't know how you measure AC operation in your line of work, but if you can convince anyone that warmer, more humid air is going to cool the truck down faster than colder, less humid air, I'll be amazed.

 

[ColoradoCub]

No it doesn’t. If you cut off flow completely, you have stagnant coolant in your core and lines for months. Sounds like a bad idea. Also, you lose all heat functionality. Weather isn’t constant. Cool summer nights happen, and maintaining HVAC function requires some heat. You can greatly reduce the flow and still get better AC temps without completely cutting off the flow.

You don’t know what you are talking about, I have now experimented with the faulty AC on both my 2019 and my 2020 with valves hacked into both of them. I’m well aware that you have no heat with the valve closed completely off but that’s the only way you can get cold AC instead of this 50 + degree BS AC. Many of us have run the valve closed completely off for all of last summer. I tested my truck out last winter and with temps outside at around 20 degreees and with the valve completely open and AC set on fresh air the coldest I could get my AC to blow was 52 degrees. That clearly shows that the blend door for the heat does not close all the way. Any other vehicle with fresh air open and 20 deg outside air temps with the AC on would blow crazy cold, but thats because the heat blend door actually closes!

 

[Timeless]

Because it seems ineffective. that's alot of HOT cabin to cool down at first. Rolling down the windows first and letting some of that heat escape seems a little more efficient.

To each his own.

More efficient only in regards to using less fuel. But you still sweat like mad till it cools down. Whereas the remote start you get into the truck with the cabin normalized to cool depending on how long you let it go before entering.

 

[KcRay]

392DCGC
The automotive engine cooling system is a closed system, so being stagnant, (not moving) is a non issue. The coolant used today is highly treated to stop corrosion, rust, or gumming up. Also the heater core is the highest part of the system and likely drains back down to the water pump anyway, as we are not blocking off the return line. This practice of blocking off the heater core is as old as the invention of the heater core itself, and is still used widely today.

 

[392DCGC]

Sorry, but no. You're just way off. If I get bored someday I'll get an anenomometer out of the office and do a mini air flow test to show you how you're totally wrong, but it shouldn't even be necessary. I just double checked and you can, too. Sit in the drivers seat with the AC on full cool, full fan, on recirc. Put one palm in front of a front vent and the other in front of a rear vent. Feel the air. Now turn off the recirc and put your palms back in the same place. The air both gets warmer and reduces in velocity. In no way does that aide cooling. I'm well aware of over pressurization conditions and friction loss in HVAC systems as my company engineers, tests, and commissions HVAC systems, but those factors clearly don't play a part in these trucks, as is evidenced by the lay test I described above. Now, I will admit that you could be right about one thing; the louder air on recirc *could* be a consequence of a smaller opening, that is a possibility. However, the main point is that in no way is slower, warmer air going to cool the back seat down quicker, sorry.

I never said recirc cooled worse. If you had read the rest of my post, I clearly said re-cooling the same air (recirc) could produce lower temps than constantly cooling hot outside air. What I DID say was that recirc reduces airflow throughout the cab because air is no longer being forced front to rear. The blower speed isn't changing just because you turn recirc on. If it actually is blowing harder on recirc, than the fan filter is restricting airflow and should've been sized larger.

You don’t know what you are talking about, I have now experimented with the faulty AC on both my 2019 and my 2020 with valves hacked into both of them. I’m well aware that you have no heat with the valve closed completely off but that’s the only way you can get cold AC instead of this 50 + degree BS AC. Many of us have run the valve closed completely off for all of last summer. I tested my truck out last winter and with temps outside at around 20 degreees and with the valve completely open and AC set on fresh air the coldest I could get my AC to blow was 52 degrees. That clearly shows that the blend door for the heat does not close all the way. Any other vehicle with fresh air open and 20 deg outside air temps with the AC on would blow crazy cold, but thats because the heat blend door actually closes!

Oh boy, sure don't know what I'm talking about even though I tested it the same as you did. I never said leave the flow wide open. You leave a trickle flow, still get heat, and still get colder temps. Is it as cold as completely closing off the hose? Nope. Is it colder than stock? Yes.

 

[slicktop]

I never said recirc cooled worse. If you had read the rest of my post, I clearly said re-cooling the same air (recirc) could produce lower temps than constantly cooling hot outside air. What I DID say was that recirc reduces airflow throughout the cab because air is no longer being forced front to rear. The blower speed isn't changing just because you turn recirc on. If it actually is blowing harder on recirc, than the fan filter is restricting airflow and should've been sized larger.

Yeah I read that, and it's also wrong. First you say "blower speed isn't changing" then you say "if it is", but let's move on. The air velocity absolutely increases on recirc, and it's not due to the fan filter restricting airflow. It's actually common with all squirrel cage style blowers. You can do the experiment yourself with a surplus blower fan out of a residential AC system. Hook it up to power and note the air speed out of the blower. Now take a piece of plywood and block off one side of the blower intake, and you'll notice the air velocity increases. There's videos of this on YouTube, you don't have to do it yourself. Squirrel cage motors actually come with a chart showing how much output they'll produce with a given amount of inlet air and friction; it's a design variable and isn't intended as a constant, nor does it mean the filter was designed wrong. But again, just try it yourself in your truck. The velocity noticably does increase on recirc.

 

[User_3336]

I've never sweated in my truck. I use a sensible method to cool off before I flip on the a/c.
Use the method that keeps you happy.

More efficient only in regards to using less fuel. But you still sweat like mad till it cools down. Whereas the remote start you get into the truck with the cabin normalized to cool depending on how long you let it go before entering.

 

[Timeless]

I've never sweated in my truck. I use a sensible method to cool off before I flip on the a/c.
Use the method that keeps you happy.

You must live in a fantastic climate area then. Here in SC it gets triple digits with 90% humidity and you start sweating walking to your truck. Cannot imagine how awful it would be to enter a fully heated truck that has sat outside for hours and hours.

 

[z0n3]

Installed the HF fluid clamp today. Before I used to get 46 out of one vent, the others were all 54. I was able to get 43.9 consistently out of all of the vents. Truck said it was 91 outside (more like 85). I took these temps while the truck sat, it didn’t get driven at all. I will have to take temps during my commute tomorrow to see how she does.

 

[User_3336]

In motion, on the road, you will probably get down to about 40 on max a/c recirc.

QUOTE="z0n3, post: 310670, member: 14911"]
Installed the HF fluid clamp today. Before I used to get 46 out of one vent, the others were all 54. I was able to get 43.9 consistently out of all of the vents. Truck said it was 91 outside (more like 85). I took these temps while the truck sat, it didn’t get driven at all. I will have to take temps during my commute tomorrow to see how she does.
[/QUOTE]