A/C not cool enough/ compressor cycling - Dodge Cummins Diesel Forum
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post #1 of 18 (permalink) Old 08-13-2019, 10:09 PM Thread Starter
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A/C not cool enough/ compressor cycling

I have got vent temps at 60 on a 80 degree day here and the passenger side vents are warm compared to the 60 deg drivers side.
I have read this is mostly caused by low freon so i hook my gauges up and i had 42psi on low side and 350psi on high side.
Seems to high on the high side at least. Should i be checking at idle?
Also, compressor doesnt engage for all that long keeps kicking on and off.
Does high pressures mean overcharged? because other things are pointing to too low freon.
So just trying something i recovered some freon from the system and got my pressures to 28psi on low side and 270psi high side made it slightly cooler but a bigger difference in how warm the passenger side air is coming out.

Should i try replacing the liquid line?

My fan has some resistance it doesnt spin freely with the truck off if that tells you the fan is working properly just from what ive read


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post #2 of 18 (permalink) Old 08-14-2019, 08:55 AM
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Quote:
Originally Posted by Diezl View Post
80 degree day
42psi on low side and 350psi on high side.

Should i be checking at idle?
Also, compressor doesnt engage for all that long keeps kicking on and off.
At idle, 80F day, the low side should be 40-50, high side should be 170-210.
So your condition fits "low side is normal or slightly high and high side is too high".

Possible Causes:
Condenser air flow restricted
Inoperative cooling fan
Refrigerant system overcharged
Air in the refrigerant sytem
Engine overheating

This info comes directly from the FSM.

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post #3 of 18 (permalink) Old 08-14-2019, 12:38 PM
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I am having this same problem. So this is what I have done so far...replaced all flapper doors. Regained directions and ac/heat control. Replaced console, regained selections/eliminated component. Replaced compressor, drier, high side line. All leaked or due to age.

Took it back to my A/C man to dial it in for R134. I have heard the system is sensitive to amount. He double checked the rated capacity. Said itís something else or his new compressor isnít working /leaking and he canít easily check seal due to clearances at the pulley. Under warranty. Check other causes and come back.

I bought a new Mopar fan, fan resistor, pressure sender, and evaporator temperature sender. VDO Fan is not blowing hard and does not work on settings currently.

I am also converting the old evaporator temperature sender to post-Ď06 sender also because you cannot get Ď06 anymore. I will clean my evaporator and check it for leaks. Unknown if it has ever been changed but we could not tell if it is/was leaking as nothing was leaking from the drain. I have a black light and will check. System has dye in it.

After these installs and checks, we should find the issue with my 2006. If not I will find a cliff.




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post #4 of 18 (permalink) Old 08-14-2019, 01:19 PM
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check for equal or correct flapper operation.
also loose mis aligned ductwork leakage


This reminds me .... my 05 blew lil black rotten pieces of foam out the vents from the day i got it , to the day i sold it . lol
Funny now , not so funny then.

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post #5 of 18 (permalink) Old 08-14-2019, 09:05 PM
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Check orifice tube as well.
Check condenser for blockage/damage and that fan clutch harness is unscathed.

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post #6 of 18 (permalink) Old 08-14-2019, 10:39 PM
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If the above advice doesn't solve your issue, here are a couple more thoughts.

Is your condenser clean and are the fins straight? If not, clean with a spray can of coil cleaner and straighten fins with a fin comb off Amazon. Is your fan clutch working correctly? Spin test with resistance doesn't really tell you much. If it's inoperative, condenser cooling will be inadequate which can cause high AC head pressure. For a simple diagnostic, start the engine and turn on the AC. Fan should fully engage and roar within a short period of time. Mine takes less than 30 seconds. Rev the engine a little and you'll definitely hear it if it's working. For better diagnostics, you can get out a multimeter and run the fan clutch diagnostics in the 2006 FSM. Here's a link if you don't have a copy.

https://www.dropbox.com/s/rwus86v9aw...al%20.pdf?dl=0

And a link to a thread on cleaning your condenser: https://www.cumminsforum.com/forum/3...ling-fins.html

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post #7 of 18 (permalink) Old 08-15-2019, 12:17 PM Thread Starter
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Good information here guys. My vents seem to work like they should going from floor to dash.
Condenser fins are definitely smashed in some places mostly the top im guessing from someone leaning over it( just bought the truck couple weeks ago) probably full of dirt too cant really tell. Maybe i clean it or just replace it if i open up the system and need an orifice tube too they are fairly cheap.
I will have to check my fan like suggested as well then.

Is there a way to check if the orifice tube is clogged without taking the line off/replacing?

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post #8 of 18 (permalink) Old 08-15-2019, 11:29 PM
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I ran into the same thing. Temps were sort of cool. Shop checked AC pressures and checked for leaks and couldn't find anything. I replaced blend doors, blend door motors, evaporator, ac drier filter, a/c orifice tube and no change. AC compressor would cycle on/off every 8-10 seconds and would cool down when cycle on but never stay on for long. Following the wiring schematic, led to the evaporator temp sensor which sends its signal through the HVAC control panel....after all that, a new HVAC control panel fixed the issue.

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post #9 of 18 (permalink) Old 08-16-2019, 08:00 AM
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Is the suction line cold? How much superheat do you have? Doesn't sound like much of a restrictor problem with suction psi like that. Do you have subcooling at the liquid line? Those things tell you whats really going on in the coils. I plug the heater water to see if theres heat leakage when in the ac mode. Craig

I just did a search and theres plenty of reading on how to diagnose by subcooling and superheat. Learn how to do that and its as good as having windows all over the system. Pressures don't tell spit compared to SC and SH and knowing what they mean!
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post #10 of 18 (permalink) Old 08-16-2019, 09:39 AM
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Quote:
Originally Posted by BFD View Post
Is the suction line cold? How much superheat do you have? Doesn't sound like much of a restrictor problem with suction psi like that. Do you have subcooling at the liquid line? Those things tell you whats really going on in the coils. I plug the heater water to see if theres heat leakage when in the ac mode. Craig

I just did a search and theres plenty of reading on how to diagnose by subcooling and superheat. Learn how to do that and its as good as having windows all over the system. Pressures don't tell spit compared to SC and SH and knowing what they mean!
This is the next higher level for diagnostics.

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post #11 of 18 (permalink) Old 08-16-2019, 09:43 AM
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Quote:
Originally Posted by coastie View Post
I ran into the same thing. Temps were sort of cool. Shop checked AC pressures and checked for leaks and couldn't find anything. I replaced blend doors, blend door motors, evaporator, ac drier filter, a/c orifice tube and no change. AC compressor would cycle on/off every 8-10 seconds and would cool down when cycle on but never stay on for long. Following the wiring schematic, led to the evaporator temp sensor which sends its signal through the HVAC control panel....after all that, a new HVAC control panel fixed the issue.
Any AC DTC for the temp sensor?
Or you got it figured out after you did/replaced everything you could except the HVAC control module?

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post #12 of 18 (permalink) Old 08-17-2019, 12:03 PM
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Quote:
Originally Posted by PWong View Post
This is the next higher level for diagnostics.
Got that right !

I have heard the terms . BUT no idea after that .....

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