AC problems--Have you measured the temp?

[Crunch]

I have a probe type thermometer, the kind the health inspector used when he inspects food service coolers, and keep it in the vent to monitor temperature. Then following are the readings I've noticed, and they seem to be constant with the listed conditions:



Recirc - 40* regardless of time of day or night, outside temperature or amount of sun shining in the truck. Sits right on 40* once the system has run for 10 minutes or so. I've also noticed that it doesn't matter what speed the fan is running on, either. Normally, you want to pass the air over the coils as the lowest speed possible for the most efficient cooling.



Fresh - 40* at night and on days when the temp is generally less than 100*, and once recirc has lowered the cab temperature sufficiently and the sun isn't beating down on the truck. It also sits at 40* at night. Fan setting never higher than 2.



Fresh - 50*-54* on days when the temp is over 100* or the sun is beating down on the truck, and as long as I am driving at freeway speeds of about 70MPH. Fan setting never higher than 2.



Fresh - 57* on days when temp is over 100* and the truck is sitting still or I'm driving it on side streets/city driving. On the hottest days it doesn't get below that. Makes me think this new refridgerant has a sweet spot when it comes to ambient conditions, and slow driving on hot days ain't it. Fan setting never higher than 3.

 

[TFucili]

I'll grant you that r-134 is inferior to r-12 as far as its ability to cool. I have owned other cars and trucks, though, that had r-134 systems that worked far better than these do. Either the whole system is undersized for the truck, or there is some mis-match of components. The only thing I've owned with A/C less effective than this truck was a '95 Chevy Tahoe.

 

[DPKetchum]

Try using TWO to measure the left and right side vents at the same time.

 

[Crunch]

Try using TWO to measure the left and right side vents at the same time.

I checked that last night. About 90* outside, evening hours. The vent just to the right of the steering wheel was right on 40*, the vent closest to the passenger window was 43*. I haven't had any complaints about my AC, other than the inferior quality of R-134, as TFucili mentions. The old school stuff would cool your vehicle while sitting still at a stoplight on a 100* day. The R-134 seems to require significant outside air flow to assist in the cooling.

 

[JayWm]

Crunch, are these numbers with the truck parked or in motion? I ask as I am having the same issues. Except I only get the higher temps while the truck is parked or moving in stop and go traffic, or city traffic.



On the highway I get 25-30 degrees. I have found that the windshield is a giant greenhouse and having tinted helped the comfort level while driving.



My dealer wants to reflash, but can't give me more info of what the reflash is gonna do.



Jay

 

[cummins_crewcab]

My vents blow about 100* when sitting still since my a/c shuts off when I stop at a red light... Haven't had time to get go get the TSB done yet :{

 

[Crunch]

Crunch, are these numbers with the truck parked or in motion? I ask as I am having the same issues. Except I only get the higher temps while the truck is parked or moving in stop and go traffic, or city traffic.



On the highway I get 25-30 degrees. I have found that the windshield is a giant greenhouse and having tinted helped the comfort level while driving.



My dealer wants to reflash, but can't give me more info of what the reflash is gonna do.

The fresh air figures are for in motion driving, though I've noticed that at night I can get the 40* with fresh air and stopped. The recirc temps seem to be constant regardless of motion, as long as the cab has already cooled down. If you can get below freezing temps I'd say you are doing great, if not too great. I've never thought that I was having a problem with my AC, but a lot of people do seem to be having problems. On long trips I have to turn the temperature setting down a bit because it gets so cold, especially on recirc. But as DP Ketchum pointed out, constant recirc is what gets you that stank ho smell in the cab.



Once nice thing I've noticed about these trucks is that my fuel economy doesn't seem to drop because I'm using the AC. Once again, thank you Cummins, for providing an engine that can get the job done!

 

[DPKetchum]

The problem I have is RIGHT SIDE vents at times when stopping the temp will go close if not to ambient. Worse and a LOT more noticable on fresh and on high temp days like high 80s to mid 90s. Its a blast of warm/hot air. D/side stays ok. I'm running two ac thermometers. Also when this occurs and as I pull off the d/side vents blow vapor of condisation and the thermometer in pass vents fogs over. No matter what the humidity. If you stop every 5 miles or so and then pull off it does it time after time. On recir it stays pretty consisdent from side to side(withen 3 or 4 degrees of each other.

 

[JayWm]

I have to run it on recirc to get it to really cool down and when I stop or am driving in traffic it starts to climb immediately. I have checked my other vehicles that I drive and none of them do this. In fact my 02 work truck will get so cold you have to turn the heat on and this is while its parked. Something is not right on these 3g trucks AC systems.

 

[JNeves]

What dealer are you going to?

 

[Matt400]

At work on the west coast we find vent temps of 43 is the cut off of being ok. . so 43 and below is good to go where 44 and above call for attention.



Crunch- are you sure you don't need this TSB done-

http://www.dodgeram.info/tsb/2004/18-003-04.htm



I had that done on my 03 and it fixed the high vent temps at idle speeds.

 

[DPKetchum]

On fresh the ac performance in general with mine is poor. My 1993 W250 never had the ac touched in the 7 years I owned it. Would freeze you out of the truck. All the vapor mine produces and fogging up the pass side thermometer is indicating a problem of warm/hot air pouring into the system I think. Any thoughts?

 

[Crunch]

At work on the west coast we find vent temps of 43 is the cut off of being ok. . so 43 and below is good to go where 44 and above call for attention.



Crunch- are you sure you don't need this TSB done-

http://www.dodgeram.info/tsb/2004/18-003-04.htm



I had that done on my 03 and it fixed the high vent temps at idle speeds.

No, until you posted that I wasn't aware of that TSB, and I had it in to the dealer this last Spring. Funny thing is, until you posted that link I didn't think I had a problem with my AC, but now I'll check. My truck and engine were manufactured in the Spring of 2003, so it falls in the range specified. Thanks for the info. The vents on the driver's side and passenger side are pretty much the same; it's just the temps rising while standing still and the AC set to fresh air.

 

[Matt400]

I would just print that TSB and hand it to them. That TSB I think slips by many because its not listed in the A/C section.