sevobuck

Okay, here is some history on my truck. 2006 Mega Cab Laramie 56K. I bought it from a Dodge dealer in Illinois and upon taking delivery of it found out the A/C did not work at all. I had noticed on the Carfax that the truck had been into the shop for HVAC work previously. I purchased it on a Saturday and apparently their shop was closed so they agreed to pay my local dealer to do the A/C repair. I took it in and they said I had in the evaporator and possibly the lines so they replaced the evaporator, accumulator, liquid lines, and o-ring, also topped off coolant. I thought every thing was good when I picked it up (because they said so). I very quickly found out that the air flow was very poor and the cooling ability was mediocre. After a 2 hour trip in the truck, the the air was warm and a huge chunk of ice fell off the accumulator.
I took the truck back a couple times and they checked the pressures and said everything was good. In the mean time I also noticed a whistling noise coming from the right side when the recirc button was on. I thought the cabin was pressurizing but even with the window cracked or open it still whistled (the whistle turned out to be a couple of broken tabs on the windshield cowl).
Even though none of the doors were broke, I figured the poor air flow was the blend doors so I ordered all 4 doors from heatertreater. Heatertreater doors are a solid product but there is definitely room for improvement. I choose to have the whole plenum taken out to have the doors put in which is not the recommended way to put them in from heatertreater but I can't stand the thought of putting more holes in the plenum and then putting tape over the holes. This being said, there is a lot of "slop" when the factory actuator arm is placed into the heatertreater door. So much that if the hairpin that is provided is not bent a little, there is a possibility that the arm could come out of the hole. Another thing that was not given much thought was the flipper doors that divert air to the vents in the back (for the Mega Cab). Since there is no place to attach the actuator arm to the Mode 2 door (which also controls the flippers to the rear) you basically have to decide if you are going to A) fix the flipper doors in a permanent "half open" position or B) close them completely and have no flow to the rear. I chose "A" for the simple reason that if I wanted to divert more air to the defrost vent (because that is what the Mode 2 door does; defrost or floor) I could always reach back and close the vents in the back.
Other observations I noticed about the Dodge A/C system...there is a mesh screen that goes over the top of the vents on the A/C plenum that go to the center vents. This mesh is pretty tightly woven an something that I believe causes a great amount of obstruction to flow (and one reason why it sounds like the system is blowing hard and not much output; no, I did not have any broken doors). I'm not 100% sure why the screen is there but if it is a filter then it is a poor one; maybe it keeps debris from falling down further into the plenum. I took a picture on my phone as an after-thought and as you can see I had already started to remove one side. This screen removal made a notable difference in the air flow.

The second thing I noticed was the passenger side vent had approximately a 1/8 to 1/4 inch gap between the conduit and the vent which probably also contributes to such low flow out that vent. I taped it up nice and tight.
So after that brief history I now have this to add. Even though the dealer says my pressures fine, I think low side 29-35 and high side around 275. My accumulator and lines keep freezing up. When I say freezing up, I mean hardcore ice covered as you can see in the pics. They have completely ran out of ideas at the dealership and say that the thermistor is working properly as well. Does anyone have any ideas or anything else that could be causing this? I did have them add 2 extra ounces to the system as I had heard that this could possibly help. It still ices up just as badly as it did with the correct amount (30oz, my truck was built 1-06). I would really like to get this fixed. I know I could turn the A/C button on and off to let everything thaw but should I really be expected to do this? There have to be other Mega Cab guys that don't have to turn their A/C on and off to thaw it out. I am all ears....

Accumulator frozen (94 degrees Outside)


Vent Temp when frozen


Screens on-top of plenum box (middle section) one cut out already

Spooler

That is a sign of a low charge. It is possible that the temp thermister sensor is in the wrong spot on the evaporator. What were the pressures high and low? The R134 fill is the same from 03' to 07' 5.9 trucks. You have to convert oz to lbs. An A/C machine adds by weight in LB's or Kg's. 30 oz or 1lb 14 oz is = to 1.88 lbs for the factory fill. They have got something wrong. You can put 2.00lbs in it with no issues.

Spooler

If the Dealer Tech is stumped. Get him up here on the board and we will get it straight.


Oh yeah, the temp sensor on the Evap is called the Fin temp sensor.

sevobuck

The first time they recharged the system (with new components) the admitted their machine put the wrong amount in but has since has it recalibrated. The second recharge (when they pulled the plenum to replace all the blend doors) they said they put in 1.9lbs or approx. 30oz. I drove the truck no less than 10 miles out of the city and the accumulator was frozen. Low pressures were 29-35 and high were around 275 (not 100% sure about high side number). Thermostat sensor was in the D/C suggested location.

Spooler

Did they put on the upgraded orifice tube line? DC upgraded them in 06' to a bigger orifice. I still think it is low. They can put 2.00lbs of R134a in it with no issues.

sevobuck

They put in "Line-A/C Liquid" PN 55056808AA.....don't know if that has the upgraded orifice in it or not.

There is supposedly 2 lbs in there as of now.

maxwellp

Looks like from the picture that the Liquid line is frozen also. My guess is that the evaporator, accumulator, liquid lines are all frozen. You will get low air flow from this. Only seen this from low charge or something stuck in the liquid line. Sounds like the Dealer is just puting in parts and not finding the problem. With is frozen up like that they should be able to find the problem if not find a new Dealer.

Boudreaux

Spooler, do you think that moisture in the system would cause this?

(Not vacuuming or insufficient vacuuming)

Spooler

It's possible. If air was in the system you would get some funky pressure readings. Hard to say what is wrong from here.
It's a do-over...LOL I would recommend the flush the system one line at a time and see what comes out.

madhat

What spooler said.

You need to quit messing with that dealer and find a good AC guy.

sevobuck

Yep, so far I have had to put $678 of my own money into the truck. The dealer that I originally purchased the truck from footed the $1100 bill for the evaporator/line/accumulator replacement.
I would love to find a good A/C guy in the Missouri area. I live about an hour southeast of Kansas City. I'm giving them one more shot at it. I live 30 miles from the dealer I am taking the truck to so after the 4th time the drive is getting real old real quick...is there anything else I could ask them that may help in diagnosing the problem?? Thanks-Ryan

maxwellp

Get the Low and High side readings from them, also outside air temp when it was done. From that we can see what is going on. 29 PSI on the low side is very close to freezing. 28 PSI with R134a is 32. By your pictures it looks as it is lower than that.

sevobuck

Will do...I'm off tomorrow and scheduled to have them look at it again. I can't thank you guys enough for the help!

BC847

The accumulator tank and suction line frosted all the way back to the compressor is not a sign of being low on refrigerant. It's a sign of a lack of proper airflow through the evaporator. Without the proper volume of air through the evaporator, there isn't enough heat provided to boil off the refrigerant in the evaporator thus, the flooding back to the compressor.

If it were in fact low on refrigerant, you'd see the evaporator supply line and the first portion of the refrigerant circuit in the evaporator frozen over as a result of it being "Starved" of refrigerant. As such, the low volume of refrigerant supplied boils off VERY rapidly (as opposed to the evaporator simply filling with boiling refrigerant, sucking up heat) and has the condensate freeze, turning a portion of the evaporator into a block of ice.

As it stands, based on the first image, there's enough refrigerant to fill the evaporator, a portion of the accumulator tank, and spill into the suction line headed back to the compressor. You simply don't have enough airflow through the evaporator to boil off the existing refrigerant. The lack of proper airflow, the evaporator running much too cold, combined with the proper refrigerant charge will present with low suction and head pressures.

Further, if there were moisture in the refrigerant circuit due to improper/ineffective evacuation/dehydration, the moisture would freeze at the outlet of the refrigerant metering device (TXV, orifice, etc) and plug it, if not substantially restrict the flow of refrigerant, thus the evaporator will starve.

You'd do well to NOT run the system at all till it's fixed as you run a great risk of damaging/destroying the compressor due to the liquid refrigerant (should be vapor only after the accumulator tank) flooding back to the compressor can/will dilute the compressor's lube oil ruining the bearings, if not slugging the compressor with liquid refrigerant, enough to bust the valves, swash-plate/crank, etc.

You need to find a qualified HVAC tech to see what's going on with those dampers. In my professional opinion, the refrigeration system is OK.

sevobuck

Yikes! That sounds like it could get expensive real quick. That first image doesn't do the amount of freezing justice. After a 1 hour trip the accumulator was frozen all the way solid. It took almost 5 minutes before the whole system thawed out and the ice fell off. Tomorrow should be an interesting day at the dealership. In the mean time I'll keep searching for a great HVAC tech.

Thank you for the in detail explanation of things...hopefully I can use this information to guide them in the correct direction. Is it possible that the controls on the dash are broke and that is causing the dampers to be in the incorrect position?