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Discussion Starter · #1 ·
Has anyone had any issues with their A/C? I swear over the past few jaunts, it 'sometimes' feels like it is not cooling as best as it could. But then sometimes it cools really well.:banghead:


I just don't want to take it in to hear, "We didn't find anything!":doh:
 

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When I first got my truck, I took it back in for poor cooling. They said it was as good as it was going to get and it would never cool like a "chevy". In short, the dealership was no help whatsoever. Recommend that you take the temp at the air duct outlet and see what it reads. Don't know what cold enough is but I'm sure someone on here does.
 

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I started a thread about this about a year ago. These trucks don't have the best ac, but they will cool down given enough time. I tinted my windows and put an eyebrow of dark tint on the winshield and this helped quite a bit. I did use the good stuff on the front windows. I don't remember what it is called but it really blocks the uv and heat and it aint cheap. There are some mods that will improve the performance,someone else will have to chime in on those.
 

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I started a thread about this about a year ago. These trucks don't have the best ac, but they will cool down given enough time. I tinted my windows and put an eyebrow of dark tint on the winshield and this helped quite a bit. I did use the good stuff on the front windows. I don't remember what it is called but it really blocks the uv and heat and it aint cheap. There are some mods that will improve the performance,someone else will have to chime in on those.
You talking about some sort of window coating stuff, or the tint you put on? I would be interested in this if you could shed some more light on the subject.

Back to the original question, you could bypass the coolant flow to the heater core in the cab with some sort of a valve. That would make it cool down more in the cab. Is anybody familiar with the coolant routing on that side of the engine? Is it fine to just block it off with a shutoff valve or does it have to be by-passed and still flow?
 

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Back to the original question, you could bypass the coolant flow to the heater core in the cab with some sort of a valve. That would make it cool down more in the cab. Is anybody familiar with the coolant routing on that side of the engine? Is it fine to just block it off with a shutoff valve or does it have to be by-passed and still flow?


We did this to one of our JD tractors and it worked quite well. We installed a pet **** valve and shut it off each spring and turn it back on in the late fall.
 

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I had similar problems with my AC for the past year. While driving, it would become intermittent and seem like it was not cooling effectively or at all. Took the truck into the dealership when the problem first appeared a year ago; they ran a diagnostic and said they could find nothing. Told me to come back when it was not working. Well, a few months ago, when I began using the AC again, same problem appeared. Would run cool, then warm, then cool. Took it to another dealership and the technician immediately identified the problem as the harness assembly relay inside the compressor. Moving the wire harness going into the compressor actually turned the compressor on/off. So that would explain why my AC was running cold and then hot. Vibration and wind moved the wiring harness enough to cause an intermittent condition with the relay. He indicated this was not an uncommon problem and had dealt with it before. They immediately replaced the compressor(relay is inside the compressor) and my AC has worked with no problem since then. Hope this information helps you. At least it is one more answer to why your AC may not be working well.
 

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The bottom line that many of us have found is that the system was not designed to cool the mega very well. There have been technical issues, but the bottom line it is not a great system.
 

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AC Problems

I have replaced the entire AC twice,it keeps going out,they say that it builds up to much head press. in the system and dumps the r34 out the compressor,so far its about $2500 in repairs and out again.
 

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I think there is a tiny jet inline in the system somewhere. Mine got clogged after having to replace the defroster flap, guess we got some dirt in the lines when we reconnected the a/c. Maybe someone with more a/c knowledge can elaborate.
 

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Discussion Starter · #11 ·
I think I will call the dealer this week. Took it out this weekend and it just doesn't cool very well. I know it will take awhile to cool the big cab, but just putting my hand up to the vent - sometimes it is very cold and sometimes just barely cool.

Either way, there is an issue.:confused013:
 

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Discussion Starter · #12 ·
Man I wish I lived closer to the dealer I bought my truck from!:doh: They were great during the sale and talking to the service manager, they are good on the phone too!!

I told him about my issue and he just kept saying, "Bring it in!" But I want to make sure I have an issue that is repeatable so that I don't get the canned response of we can't find anything wrong.

But I found a guy at work that had a thermocouple probe that I can hook up to a Fluke meter, and then take some readings in the A/C vents, to see the actual temps. I told my dealer that I will record some values prior to me dropping it off, as it is a bot of a drive.

We'll see soon...
 

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Discussion Starter · #13 ·
Used a Fluke 87 IV meter with an 80K-A thermocouple and on the way home tonight, the vents were putting out a brisk 54*F.:whip: It was only 83*F outside, but it definitely wasn't cooling properly inside.

And the closer I got to home, the warmer it got, up into the lower 60s. Put it on recirc, and it went down to a record 53.5*F.

Oh well, another day or two of data collecting and back she will go.
 

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Air Conditioner expectations.

Hi
To obtain accurate readings. You must put mode selection on recirculation (oval symbol with the curved arrow in the center). You lose about 10 degrees of cooling when not on recirc. Put the system on max air or all flow thru the center vents depending on your knob configuration. Put fan speed on a mediumlow setting. The temp will be the coldest at the lowest setting and lose about 5 to 7 degrees on max blower due to lower efficiency at highest velocity. Driving the vehicle anything avove 20 mph will give most stable readings. In traffic or at idle, the lower air flow thru the condenser provided by the condenser fan will not be as good.

A functional system on ANY vehicle should be capable of delivering between 42 & 45 degrees at the outlets. Virtually all vehicles are capable of that or better. Ocassionally you may find some vehicle that the system will cycle on and off between 45 & 48 degrees, but not your dodge. This should be attainable right up to near 100 degrees outside. Some vehicles will get down to 38 degrees outlet temp. Now in a big cab like the Mega, it may take a bit longer to get the whole cab temp down, but the outlet temps should be as above. As mentioned, shaded windows can increase efficiency and cut down cooling times.

Now text books and service manuals sometimes have graphs & charts that show somewhat more conservative numbers like 54 degrees acceptable in 90 degree ambient. Personally I think If I ever caught one of those technical writers , I would send him off to HE** without an air conditioner.

You need to see if you can maintain those outlet temps on hot days. If not you?they have to determine if it's a gas related issue or a air distribution issue ( we are seeing recirc doors breaking on 06-07 vehicles.)

Hope that gets you pointed in the right direction.

Charlie
 

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Discussion Starter · #15 ·
Yeah, I did some trials tonight on the way home between idle & driving speeds. Then other trials between using outside air and recirc. All results were nearly the same.

Best (coolest) vent temp I read with the Fluke was 54*F. Not good in my book!


I know, back in the day with R12, we used to be able to get cars to cool down well into the low 30s. And when R134a came along, we sometimes would get in the higher 30s, but usually around 40, or low 40s. And those are just temps taken at the vents.

I'm not worried about cab cool down times, as much as I am at trying to make sure the coolest temp is coming from the vents. :thumbsup:
 

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I just keep mine on recirculation. I noticed that when I keep it on fresh air it doesn't cool very much when I come to a stop. I think keeping it on recirc all the time keeps the cab filter clean since your not taking in as much outside air. (that is if it has a filter). That was last summer though it hasn't done it this summer.
 
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