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AC Fix TSB (Pre 8/20 build trucks)

progatschnigg said:
Iv been trying to find the evap sensor specs for a while now. When i uad it on my workbench it was around 20-23 degrees celcius. My fluke meter mesured 3200ohm approx. I did a ice bath test and it was approx 8000ohm. My truck is a 19. I uploaded a youtube video showing some resistance values. Title is, 2019 Ram A/C sensor hack for colder A/C.
I will probably purchase a new sensor, maybe mines out of spec. But for now its working great. Thx.
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@progatschnigg
I also have the 19 Limited and even with the TSB done the AC leaves much to be desired.
Your "custom sensor" sounds like an easy fix, do you need a scanner or any reprogramming to make it work?
 
I think I'm not going to bother with a TSB, I tried last fall and as I expected they said "it's fine, no problems".
Would rather do this mod by myself instead of letting some grease monkey wrench on my truck.
 
johnnyroastbeef said:
@progatschnigg
I also have the 19 Limited and even with the TSB done the AC leaves much to be desired.
Your "custom sensor" sounds like an easy fix, do you need a scanner or any reprogramming to make it work?
Click to expand...
No scanner or programming. Its looking like mine, and now a few others are much better with adding resisters in parallel with the evap temp sensor.
 
MEGA HO 3500 said:
I think I'm not going to bother with a TSB, I tried last fall and as I expected they said "it's fine, no problems".
Would rather do this mod by myself instead of letting some grease monkey wrench on my truck.
Click to expand...

That's just a lazy dealer who doesn't want to do the work at the warranty rate.
The repair conditions are clearly stated on the TSB and it has nothing to with them.
If you describe the condition, they are supposed to fix it... full stop.

1689082728870.png
 
MEGA HO said:
I think I'm not going to bother with a TSB, I tried last fall and as I expected they said "it's fine, no problems".
Would rather do this mod by myself instead of letting some grease monkey wrench on my truck.
Click to expand...
Hello,

If at any point you decide to go the dealership route to have this addressed and would like an extra layer of support, please feel free to reach out via private message. We would love the opportunity to assist.

Lex
Ram Cares
 
UPDATE;
another member has installed and tested my resister mod. Railfan413
His AC is colder than ever on a 21.So thats makes 2 of us now. All it takes is a resister of 28.5, or 29K ohms. With a couple hours of removing the glove box and finding which resister works to get the vent temp down to 40-43F.
 
Wonder if it would work on a '22? Mine is slow to cool down. Once it's cool inside, it does ok.
 
Yes! I've had very good success with this modification on my 2021 Ram 3500. I found my A/C to be okay, but definitely the least impressive I've ever experienced. At 28.5k ohm resistance my A/C has been consistently sitting at 40 degrees. I'm still in testing faze to be sure my evaporator doesn't freeze up at 40 degrees. In Pennsylvania the weather has been constantly 85-90 degrees with high humidity. Perfect testing conditions for this sort of thing.
 
RamCares said:
Hello,

If at any point you decide to go the dealership route to have this addressed and would like an extra layer of support, please feel free to reach out via private message. We would love the opportunity to assist.

Lex
Ram Cares
Click to expand...
that wold be nice, my dealer flat out refused to do the SIB for the A/C. I ended up adding a valve to the heater core to stop coolant flow in the summer.
 
progatschnigg said:
UPDATE;
another member has installed and tested my resister mod. Railfan413
His AC is colder than ever on a 21.So thats makes 2 of us now. All it takes is a resister of 28.5, or 29K ohms. With a couple hours of removing the glove box and finding which resister works to get the vent temp down to 40-43F.
Click to expand...
Do all HD Ram trucks have this sensor or just the trucks that have automatic temperature controls? I have a Bighorn with the manual ac system.
 
thecastle said:
that wold be nice, my dealer flat out refused to do the SIB for the A/C. I ended up adding a valve to the heater core to stop coolant flow in the summer.
Click to expand...
Hi there,

We're sorry to hear that. Please send us a private message with some additional details, so we can see how we can further assist you.

Lex
Ram Cares
 
It looks like SENSOR, EVAPORATOR FIN PROBE part number: 68396 045AA is the one the resistor is added to.

My 2020 Bighorn 6.4 has that sensor even with the manual HVAC..

hdrams.com

Looking for a Part Number? Must provide VIN (only up to model year 2020 at this time)

Looking to see if my 2020 Bighorn VIN 3C6UR5DJ7LG223246 with the manual AC has the AC temperature sensor mentioned in the post link below. https://hdrams.com/forum/index.php?threads/ac-fix-tsb-pre-8-20-build-trucks.3162/post-268162
hdrams.com hdrams.com
 
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progatschnigg said:
I didnt measure it. But the amp draw is very low. Its just a small sensor altering its millivolt signal.
Click to expand...
So if I was going to order a resistor to do this what size should I order? Would a 22k be ok? I don’t see any 24.4k. I’d rather not try to get the right assortment of resistors. I don’t know a lot about resistor math lol.
 
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