My A/C stays engaged all the time.

[Nystagmus]

https://www.ramforum.com/threads/ac-stays-engaged-all-the-time.166634/

This thread was over in the electronics forum. Thought I might get more responses here.

On my 2014 Longhorn I can’t turn the A/C off. Even on Vent… the compressor runs non stop and the air is cold, not just outside temperature air.

Help !!! Trying to prevent undue wear and tear on my ac system.

 

[Nystagmus]

Bueller…..
Bueller…..?

 

[indept]

Pretty much the same here. It seems to do it most in spring & fall. Mine doesn't engage in winter unless the defroster is on.

 

[Nystagmus]

Sometimes I just want the freakin vent to blow outside air !!! Like 8-9 days a year…. And when just running heat, no reason to run the compressor all winter long !

 

[chris1126]

lturn the thermostat knob down just a click or 2 and then see if the ac disengages

 

[Nystagmus]

lturn the thermostat knob down just a click or 2 and then see if the ac disengages

I’ll try that today…but I’m not holding my breath.

 

[Ricks Ram]

I’ll try that today…but I’m not holding my breath.

Since your truck is a Longhorn it has the Dual Zone ATC as standard equipment. There is a Humidity Sensor on the 14 and up 1500 trucks located to the right side of the rear view mirror covered by a small black cover that attaches to the windshield. This pops off to access the sensor that controls the compressor clutch engagement if there is moisture on the inside of the windshield. If this sensor is bad or you have some type of an issue with the wiring or connections the compressor will stay on by default whenever the system is in use no matter what setting you have it on in manual or automatic. When you have your truck in manual mode on vent the compressor should NOT be engaged no matter what you have the temperature set at. If it is engaging while set on vent in manual mode you have an issue of some kind. Whenever the truck is in the Auto mode the compressor will be engaged at all times. This is why I don't use the Auto mode as much in the spring and fall and just keep the truck on vent to save the wear on the compressor. I have seen this issue with other trucks in the past and it was corrected by replacing the humidity sensor but there is no guarantee that's what your issue is. If you have the Alfa tool you can also check for DTC codes that could possibly point you in the right direction.

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[Nystagmus]

Thanks Rick. I don’t have a scanner, but maybe Autozone would check for codes ?

 

[Ricks Ram]

Thanks Rick. I don’t have a scanner, but maybe Autozone would check for codes ?

A regular scanner cannot check for DTC (Diagnostic Trouble Codes). They can only check for OBD (On Board Diagnostic) codes. You would need the Alfa tool or similar tool to the dealer. We are very familiar with this because we actually added the Dual Zone ATC to our trucks and had this exact issue until we figured out it was the fact that we didn't install the Humidity Sensor when we did the upgrade. After installing the sensor and wiring the system acted correctly. Unfortunately not having the sensor did not generate a DTC code so we basically figured out what was wrong by trial and error. I have helped two other members that had the same issue with factory installed ATC and they were both corrected by replacing the sensor. This doesn't mean that's what's wrong with your truck but it's a possibility. The Alfa tool or dealer could possibly tell you if there is anything else going on. Unfortunately most dealers are clueless and usually aren't much help and are more interested in draining your wallet instead of fixing your truck. The Humidity Sensor is around $50 and can be replaced in around 10 min. I usually never recommend just throwing parts at a problem but in this case since not having a Humidity Sensor didn't set a DTC code in our trucks and it's one of the systems that will make the compressor stay on by default you might want to pull the cover and check the connection and if it looks ok possibly replace the sensor to see what happens. Lots of guys do the ATC upgrade and need the sensor so you could easily sell it if it's not the problem.

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[Nystagmus]

Thanks for the info. I checked the sensor wire this past weekend. It all looked intact. I just hated to spend $50 on a part that might not fix the issue !!!

 

[Ricks Ram]

Thanks for the info. I checked the sensor wire this past weekend. It all looked intact. I just hated to spend $50 on a part that might not fix the issue !!!

I agree, but unfortunately you're going to pay a dealer or someone else around $100 Min to check for DTC codes that may or may not be present and this is money you can't get back. There is no way to diagnose the problem other than checking the wiring and connectors without the correct scan tool. If you purchase a new sensor and it doesn't correct the issue you can sell it on the forum to someone who is upgrading to the ATC and recoup some or all of your money. Since a missing Humidity Sensor did not set a DTC code in our trucks when checked with a scan tool it's possible it wouldn't set a DTC code even if it was defective in your truck. There are definitely a few different ways to go about it.

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