2012 Dodge Ram 1500, 5.7 Liter, Strange A/C issue

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m_misztal

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I'm hoping someone can help a new member out!

I have a 2012 Ram 1500 with the 5.7 liter hemi that had to have the evaporator changed out. The shop I used didn't have a sophisticated machine and charged it as best as they could. Turns out that it was 9 ounces low. I had a professional shop vacuum it down for four hours, and it held the vacuum flawlessly for 2 hours.

They then charged it with the exact amount with a digital machine and it works amazing now!....but only at idle.

When I drive, it works, but not as well as it does at idle. Essentially, when under a load the compressor doesn't stay on as long as it should and I can feel the air get a bit warmer and it smells a bit stale, if that makes sense?

I was wondering if anyone has had this issue, and has found a solution? My initial thought is that the a/c pressure transducer is marginal, and should be replaced, but that is a complete shot in the dark.

My other thought is that the mounted orifice tube is partially blocked, or the same scenario with the expansion valve.

Any and all help is appreciated!

Thanks in advance.

Marc
 

Demon-HeMi

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id say there is too much Freon in the system and its got too much pressure when the motor is running harder, id let a little bit out at a time and see if it gets better, been there done that before
 

crash68

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You would need to get some gauge readings to determine what's happening. If the second shop weighed in the correct charge, it's probably a restriction issue or something mechanical with the compressor.
 
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m_misztal

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Thanks for the responses everyone! I actually found the issue, and it was one that hasn't been mentioned before on any forum I've come across for ram trucks.

I have a faulty evaporator temperature sensor. I removed the lower glove box, then removed the upper box by undoing a screw, and started looking for the sensor.

The sensor was on top of the box and had a 2 wire connection running to it.

1. It was not pushed in the box all of the way.
2. It was not connected all of the way.
3. It was coated with residual freon.

The part removes without pulling the dashboard (thank god)

Took it out, cleaned it and put it back in. The a/c is working MUCH better now, but not as well as I remember it. I ordered a OEM Mopar one for 19 bucks last night, I'll let you know if it helps!

FYI, the information that led me down this path came from a dodge caravan forum...
 

Tpearson515

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Have you added a cab air filter now? Restricted air flow to the evap will reduce suction pressure causing your system to short cycle. Also condenser condition can have a large impact to how your system removes heat. With what crash said you would need some gauges to see what your pressures were doing under high idle,
 
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m_misztal

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I was able to install the new part over the weekend and it completely took care of the issue.

Part was 15 bucks online for a genuine Mopar replacement.

Blowing like a champ at 38 degrees at both idle and highway speeds now!
 

Demon-HeMi

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did you have to discharge the system when you changed the sensor? and pictures of the process?
 

nateinva

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I was able to install the new part over the weekend and it completely took care of the issue.

Part was 15 bucks online for a genuine Mopar replacement.

Blowing like a champ at 38 degrees at both idle and highway speeds now!
I'm having a similar issue on my 2011. I just had my compressor and expansion valve replaced and system recharged. Blowing 38 degrees at idle but it fluctuates a bit while driving the highway. Better again at stop lights, etc.

I think I can see the sensor when I pull lower glove box....right on top. Can you share a part number? Also, where is the screw to remove the upper glove box?

Thanks!
 

nateinva

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Found the part number...68004239AA

I guess I'll order one and see if it helps.
 
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m_misztal

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@nateinva

That's the correct part/part number!

Essentially, I had three things to remove in order to get the upper glove box to come out.

1. The USB port which is removed be pressing up and pulling out.
2. A wiring harness in the upper left corner which just pulled out.
3. A single philips screw that is located in behind the upper glove box and approximately in the middle.. (you have to lay on your back and look up to see it easily.

I'll try to snap some pictures tonight to provide some more guidance. Feel free to shoot me a direct message.

The part is simply an electric sensor that has a wiring harness that connects to it. There isn't any freeon involved with it, so discharging the system is completely unnecessary.
 

nateinva

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@nateinva

That's the correct part/part number!

Essentially, I had three things to remove in order to get the upper glove box to come out.

1. The USB port which is removed be pressing up and pulling out.
2. A wiring harness in the upper left corner which just pulled out.
3. A single philips screw that is located in behind the upper glove box and approximately in the middle.. (you have to lay on your back and look up to see it easily.

I'll try to snap some pictures tonight to provide some more guidance. Feel free to shoot me a direct message.

The part is simply an electric sensor that has a wiring harness that connects to it. There isn't any freeon involved with it, so discharging the system is completely unnecessary.
I ordered one yesterday, thanks for the follow up. Don't worry about pics for me, unless you want to update your thread for other readers.

I'll post back once I install to see if it takes care of my intermittent issue. It's exactly as you've described and I never knew about this thermostatic sensor before seeing your post recently. Good info...

I recently added the cabin filter to my 2011 after purchasing my truck used. Hoping that'll help crud from reaching the evaporator and prolong life.
 

nateinva

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@nateinva

That's the correct part/part number!

Essentially, I had three things to remove in order to get the upper glove box to come out.

1. The USB port which is removed be pressing up and pulling out.
2. A wiring harness in the upper left corner which just pulled out.
3. A single philips screw that is located in behind the upper glove box and approximately in the middle.. (you have to lay on your back and look up to see it easily.

I'll try to snap some pictures tonight to provide some more guidance. Feel free to shoot me a direct message.

The part is simply an electric sensor that has a wiring harness that connects to it. There isn't any freeon involved with it, so discharging the system is completely unnecessary.
Thanks again for posting about this sensor. Got mine in the mail today, swap took about 10 minutes. Just finished a drive thru town with ac turned down to low on full blast. Working perfect so at this point I'm saying this was the problem. Cheap easy fix...
 
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