2004.5 Air Conditioning Problem & Fan Not Cycling At Idle

[MJWenrich]

Since new, my 2500 dual control Laramie A/C system has not functioned as well as what I would like. Although, a few rare times, it seemed the air has been colder and seemed to be operating correctly. Very few times I might add. Years ago when I was taking the truck into a dealer for warranty service, I complained about the air temp, mostly at idle, and after reading a 2004 post on this forum about 2003 TSB 18-043-03, I referred to that at the dealer. I was told that TSB did not apply to my truck, even though it would not pass the fan test described. When driving at speed and pulling a hill towing I can hear the fan kick in as the temp goes over 210. But I never hear it at idle.



Now, I noticed that the passenger side air is warmer and after reading another recent post, I plan to top off the refrigerant. All of the ducts/controls are working correctly so I have not experienced that breakage yet. Adding a little freon may cure the at speed temp problem but what would cure the idle warm air condition and the fan not engaging? We are going to be heating up quite a bit locally in the next week and that will be a good time to test the system I would guess. And add the freon. Suggestions appreciated.

 

[p-Bar]

Some guys have added a mystery switch to over ride the computer and turn it when they know they will be needing it .

here is a thread read from #20 and down

https://www.turbodieselregister.com...sion-Temperature&highlight=fan+overide+switch

You are fooling the computer that the temp is 220 thus turning on the fan. This is also great for backing up with a heavy load as the trans temp seems to peak real fast

 

[MJWenrich]

From reading that thread, and my head is still hurting from the data upload, it seems there is an on going problem with the fans engaging and how long they last. Switching them manually seems a good solution for the trans problem of over heating but not much is mentioned in there about air conditioning. I do have a manual switch on an older vehicle that does not have a computer to "fool". I guess I will have to try to trouble shoot the fan and see if it is bad. The 2003 TSB may not apply since there were changes in the ECM setup for 2004. I seem to recall that the fan used to cycle at low speeds on warm days. The test of running the blower at full speed on A/C does not make the fan engage so there may well be a fan problem. Thanks for the link.

 

[MJWenrich]

Well, I added a can of 134a and the temp cooled somewhat but only to 60 degrees at the vent on the extreme left. So I decided to go to an a/c shop. They drained it and refilled saying that the system appeared to have air bubbles and they could only detect the can of 134 I had added. After the refill, the temp is still only down to about 50-55 degrees and the fan still does not kick on with the air on full blast. So I can cool it on max air but it still is not what I would call a great a/c and never has been. I suspect the fan is some of the problem at idle but that would not account for the less than 45 degree air at the vents. Still trying to determine what is wrong but thought I would update this post for others.

 

[sag2]

What is the ambient when you are measuring the outlet temp? As a very general rule you will never see more than a 40 degree difference from ambient. So if it was 100 degrees the best most systems will do is 60 degree air. Notice I said general rule, some vehicles do better, some worse, but if you average all cars it is pretty accurate. In the R12 days it was 50 degrees or better.

 

[MJWenrich]

The 60 degree reading came with an outside temp of 85-90 degrees. The temp at the shop when it was serviced was in the 100 degree range. As an update, I went on a 250 mile trip a couple days later and the system worked about like when the truck was new (not as good as our Suburu Outback with similar space to cool) but good enough to keep the windows up. But slowing into traffic signals and lower rpms brings back the heat and no radiator fan kicking in. I have to run between stoplights in the max a/c mode to get any cooling below 1200 rpm. Much better now than it was and it was about 103 at times while on the trip. Probably have a rad/fan clutch problem.

 

[hawkdriver]

I had the same problem with my 04. 5 3500 dual A/C control Laramie as well last summer. There where 2 issues and it took me forever to hunt them down. The first issue with the difference in temp was that I had installed a satellite radio receiver and the power adaptor that was spliced in behind the radio, fell loose and blocked the temp mixing door on the right side of the truck. 2nd issue was the A/C compressor having intermittent operation. Turns out that the electrical connection between the truck and compressor was bad, it was loose so that it would work sometimes but not others. I ended up cutting the plug of both the truck harness and the compressor and soldiering the connection. Works like a champ!

 

[MJWenrich]

Hawkdriver... . does your truck have the problem of very little a/c at idle or low rpm? And does your radiator clutch fan kick on when you go to the highest fan setting on regular flow thru a/c? I am trying to determine if the 2004. 5 has the same system as other years trucks. If no one else with a 2004. 5 Laramie has good a/c at idle then maybe it's the nature of the beast. Going to max a/c (middle button) does help at idle but you have to put up with the noise of the unit as well. It goes to full blast air recirculating thru the truck cab. Just seems it should work better than it does.

When I complained about the poor cooling when it was new, the service managers (yes, more than one) said it was normal for these trucks. The standard answer. Since I was working for a living I chose to make money rather than spend my days at the dealership. My truck was already spending quite a bit of time there with a rear end howl problem. Too bad Mopar left Dana and went to American axles in my opinion.

 

[ScottRoberts]

I've been having issues with mine for about a year or so as well. The problem seems to be when I start the truck and let it idle in neutral with no load, the compressor cycles somewhat rapidly and blows ambient air. If I am idling in gear or at speed the AC will begin working. I finally decided to take it to my local mechanic, he diagnosed it as a bad fan clutch that was not engaging at idle. They intended to replace the fan clutch but ended up cleaning the connections and could not duplicate the symptoms while in their possession. The day after I picked it up, the symptoms appeared again, but not as often. I dropped it back off that afternoon, as they had ordered a replacement fan clutch but decided not to install after they cleaned the connections and could not duplicate symptoms. They replaced the fan clutch the next day but were still having the symptoms and put the original back on without charging me anything. They do not specialize in diesels or Dodge's so he told me he wanted to ask around for ideas as to what may be causing the issue.

It sounds like some of the issues in this thread are similar and I look forward to seeing if the OP has any luck getting his AC working again.