Air conditioning Hack

[James Cole]

This was just a theory before people spend money on clamps and valves.

I work in a big store where things are sold on pallets. Some of the giant coolers have a roll-up door run off a motor and a small computer. The computer counts rotations of the motor to know when the door has rolled all the way down to shut off the motor. It knows all the way up based on a lever it hits.

If you manually adjust the door up a foot off the ground and then hit the open switch, the door will roll all the way up, but when it goes to close, the door will stop at a foot off the ground.

I was applying that logic to the blend door as after I did this, I did get cooler temps. What is odd is now it is back to the way it was. Sometimes I get freezing air out of the vents, and sometimes I get cool air.

We seem to have isolated this issue to the blend door - how can we focus on that instead of clamping or shutting off the heater core? Has anyone peered up into the cabin air filter box to see what is reachable from there? BTW, I am just spit-balling ideas here.

Yes, you might be on to something and this theory is not far fetched at all, thank you for that.

About checking the doors physically if someone more mechanically inclined could access them then we might find other less invasive solutions.

 

[jkm312]

Nice job!!! Great info! I will order up the 3/4 size right now. I might get 2 .. valves and 2 .... 3/4 pex "T" fittings to make a cross hose (between "out" and "in" water pump hoses) to avoid any chance of a problem by restricting flow. Basically create my own bypass route with 1 valve in cross hose and 1 valve just after the cross hose but still in "out" hose from water pump. Thanks to jkm312 for the 3/4 Pex size info!!! Here is diagram of my plan. Amazon for everything except heater hose that I will just get 2 feet of 5/8 from local auto parts store. What do you think? View attachment 26692

I don't think you would want to shut the heater core completely off. If you did, then the AC coil would most likely freeze up and turn into a giant ice ball. You need some warmth to control the cabin temp and avoid a freeze up where you can't get any air flow across the coils to condition and dry the cabin air.

I put a thermometer in the vents yesterday. Drove the truck out of the garage, was not heated up as sitting in the sun. It was a 75 degree day. Cabin temp dialed in at 71. It started out at 52 and began to climb as the engine came up to temp at 204, tranny at 158. Drove for about 20 minutes. Pulled the thermometer at 20 minutes and it read 68, cab was comfortable. I then turned the cabin temp down to 61. Vent temps dropped back to 52 and stayed there. Turned the cab temp back up to 71 and the vent temps climbed accordingly.

I live in Southeast Iowa along the Mississippi, we are just caught in this never ending cycle of rain. We are 10 to 15 degrees below normal. I haven't had a chance to see what it does on a really hot day. What I saw yesterday tells me the system is working as it should. I tested it as much as conditions would allow. I have a hand held lazer thermometer. What I want to do is take reading on the suction line right out of the AC compressor and then just as it goes into the firewall and see what the difference is. I want an 85 plus day to see what I get when I know the AC is pumping at full capacity.

For those of you that are in the south, if you have time try what I did and see what your results are.

Finally I wish someone from the mother ship would comment on all of this, instead of watching all of us flop around out here.

 

[RPeezy]

I put a thermometer in the vents yesterday. Drove the truck out of the garage, was not heated up as sitting in the sun. It was a 75 degree day. Cabin temp dialed in at 71. It started out at 52 and began to climb as the engine came up to temp at 204, tranny at 158. Drove for about 20 minutes. Pulled the thermometer at 20 minutes and it read 68, cab was comfortable. I then turned the cabin temp down to 61. Vent temps dropped back to 52 and stayed there. Turned the cab temp back up to 71 and the vent temps climbed accordingly.

I live in Southeast Iowa along the Mississippi, we are just caught in this never ending cycle of rain. We are 10 to 15 degrees below normal. I haven't had a chance to see what it does on a really hot day. What I saw yesterday tells me the system is working as it should. I tested it as much as conditions would allow. I have a hand held lazer thermometer. What I want to do is take reading on the suction line right out of the AC compressor and then just as it goes into the firewall and see what the difference is. I want an 85 plus day to see what I get when I know the AC is pumping at full capacity.

For those of you that are in the south, if you have time try what I did and see what your results are.

Finally I wish someone from the mother ship would comment on all of this, instead of watching all of us flop around out here.

That's not really what is at issue here. The complaint is that when on full, max a/c, with the temp turned down all the way to low, the air doesn't get cold enough to cool the cab down on hot days. I live on the Alabama gulf coast, and we have had mid to upper 90s the last few days. It doesn't matter to me what temperature the air out of the vents is when set to 71, because that would never be cold enough to bring the cab down to a comfortable temperature on southern Alabama summer days.

 

[Gman]

Here comes a couple of thoughts from me (aka Master of the Obvious):
If you set it to 71, the system should figure out what it takes to get to and maintain that temp.

If you have to set it as low as it goes just to keep up, then it's not working correctly.

 

[Ickabod]

... and see what your results are.

Here are my results:
BEFORE

AFTER

 

[kjn86]

I had similar issues with AC not being the coldest and I think I may have fixed it.

All I did was sit in the truck with it set to run but engine off. Make sure it is very quiet.

I set climate control to fan speed 1 and then rolled the temp up to max. You should hear the blend door move. Then slide it all the way down to low. You should hear the blend door move again.

I cycled it a few times to make sure the door opens and closes fully. Although I cannot verify that, I believe doing this "teaches" the door fully open to fully close and allows the auto AC to figure out where to move the door to.

I get pretty cold air now, but haven't tested the vents with a thermometer.

I did this today and I swear it got colder! I had trouble getting the thermometer to agree with me unfortunately, but I did notice it. Maybe placebo effect.

 

[Jhill]

I don't think you would want to shut the heater core completely off. If you did, then the AC coil would most likely freeze up and turn into a giant ice ball. You need some warmth to control the cabin temp and avoid a freeze up where you can't get any air flow across the coils to condition and dry the cabin air.

I put a thermometer in the vents yesterday. Drove the truck out of the garage, was not heated up as sitting in the sun. It was a 75 degree day. Cabin temp dialed in at 71. It started out at 52 and began to climb as the engine came up to temp at 204, tranny at 158. Drove for about 20 minutes. Pulled the thermometer at 20 minutes and it read 68, cab was comfortable. I then turned the cabin temp down to 61. Vent temps dropped back to 52 and stayed there. Turned the cab temp back up to 71 and the vent temps climbed accordingly.

I live in Southeast Iowa along the Mississippi, we are just caught in this never ending cycle of rain. We are 10 to 15 degrees below normal. I haven't had a chance to see what it does on a really hot day. What I saw yesterday tells me the system is working as it should. I tested it as much as conditions would allow. I have a hand held lazer thermometer. What I want to do is take reading on the suction line right out of the AC compressor and then just as it goes into the firewall and see what the difference is. I want an 85 plus day to see what I get when I know the AC is pumping at full capacity.

For those of you that are in the south, if you have time try what I did and see what your results are.

Finally I wish someone from the mother ship would comment on all of this, instead of watching all of us flop around out here.

I agree totally. Maybe shut flow down by 50% or so as cool mornings you will still need heat in cab. Also, heat will be present to reduce chance of ice in humid situations but not so much to heat up chilled air from evaporator on way to vents.

 

[RPeezy]

I agree totally. Maybe shut flow down by 50% or so as cool mornings you will still need heat in cab. Also, heat will be present to reduce chance of ice in humid situations but not so much to heat up chilled air from evaporator on way to vents.

Where I live, there's no such thing as cool mornings for the next 5 months.

 

[niftyguy239]

Can confirm this works flawlessly. I had 48 degree temps within two minutes of starting the truck. Thank you brothers and sisters. I thought I was alone until I found this thread. Temp outside is 86.

 

[silverbullet]

I'm going to have to get some readings over the next few days. I've had times where I'm not pleased with the performance and other times when it seems just fine. Seems to really reinforce the blend door theory.

 

[niftyguy239]

My wife shivered as soon as she got in the truck. On a 98 degree day, being able to get these temps is nothing short of amazing. True story, when I went to Advance. The guy asked me if I owned a new Ram. I was like the tenth person since Wednesday to buy one of these. It's widespread from pretty much September 2018 build date, backwards.

 

[James Cole]

You guys are not having leakage issues with this valves?

 

[niftyguy239]

You guys are not having leakage issues with this valves?

I lost about 2 oz when I first pulled the hose off the water pump. But since then, zero issues. The parts KcRay listed are spot on.

 

[Jhill]

I am not looking at my truck right now, but wouldn’t it make more sense to install a “u” into the heater core line so that you aren’t changing the flow from the water pump? That way the water will pump towards the core and return just as it would before. (Maybe it is a simple Tee off the main lines so this wouldn’t matter). They do sell adjustable bypass valves like this, although I don’t know that I’d want the added complexity. There are plenty of U hose kits on ebay etc.

What is the diameter of the heater core line? Asking for a friend.

If anyone does this, don’t forget to cap off the heater core as well.

I’m not surprised at the results, in most vehicles the heater core is practically right next to the AC evaporator. I do wonder if there is any increased risk of evaporator freeze up or similar.

I’ve still got my fingers crossed that my dealer will perform the AC TSB next time I go in for an oil change. I will say that after my last trip to the dealer I could swear that I heard the cooling fans on high much more than I used to - not sure what update might have influenced that or if it is just my imagination.

*** Here is a 2 ball valve version with a partial/total bypass that adds the cross hose with its own ball valve. This way you can avoid flow or pressure changes from stock levels. All parts are available on Amazon. (maybe auto parts store for hose) Pex 3/4" male fittings/valves just happens to match 5/8" auto heater hose. I plan on adding this to my truck when parts arrive. Do not cut your factory hoses so you can return to totally stock with no trace after Ram comes up with fix. If you choose to add this, it is at your own risk. Also not responsible if you catch pneumonia from the colder temps.

 

[thenrich]

I ordered mine today. I assume you'd at least want a little flow to prevent the condenser from freezing into a solid lump of ice.

 

[KcRay]

I ordered mine today. I assume you'd at least want a little flow to prevent the condenser from freezing into a solid lump of ice.

I have had no problems with zero flow. Running two weeks this way. No freeze up, and no added pressure problems. This is my experience, yours may vary.

 

[392DCGC]

Installed the Harbor Freight clamp today. I choked the line off completely, set the HVAC to hot, and waited for the temp to stabilize. Then I opened the clamp little by little until the temp started to rise a few degrees. Left it there so I have at least a little flow through the system. Stagnant water in the heater core and lines sounds like a terrible idea for a long period of time. Maybe the antifreeze would prevent any growth, but the heat certainly plays a roll in killing everything that would grow in there too.

At first my AC vent still showed mid 50s out the vents... wasn't happy and thought it didn't work for me, or maybe the little bit of flow was too much. Then I thought to try driving around the block. Sure enough, as soon as the truck started moving the temp dropped to 45 degrees. Much better.

 

[Feltcycle]

@KcRay Is there a reason you used the 1/2” cutoff valve for 5/8” heater hose? I assume it’s 5/8” ID, but I could be wrong.

 

[KcRay]

@KcRay Is there a reason you used the 1/2” cutoff valve for 5/8” heater hose? I assume it’s 5/8” ID, but I could be wrong.

It's part #84706 5/8
Not sure where you got that I used 1/2?

 

[Feltcycle]

Ok. The screen shot part number you posted on the first page showed 84705 which is 1/2”. Just making sure I needed 84706 (5/8”). Thanks for sharing your fix!