Automotive Air Conditioning Information Forum (Archives)

sevobuck on Thu August 04, 2011 12:19 PM

Year: 2006
Make: Dodge
Model: 2500 Mega Cab Laramie
Engine Size: 5.9L
Refrigerant Type: R134a
Ambient Temp: 84
Pressure Low: 15
Pressure High: 180
Country of Origin: United States

Originally, I had no A/C at all. Took it to the dealer and they said it had a leak and replaced the lines, accumulator, and evaporator. So, off I went. After an hour on the road I noticed that the A/C was blowing warm air. When we reached our destination I took a look and everything was completely iced over. That Monday I took it back to them and they checked some pressures and said it was still good. The other quality of this A/C system was the poor air flow. I thought maybe a blend door was broken so I bought some of the heatertreater doors and had the system completely disassembled and the doors installed. I also had them cut out a screen that was over the top of the plenum. The combination of this helped air flow through the system. They also put 2 extra ounces in the system (now a total of 2lbs, originally called for 1.8). I went on another trip and within 15 minutes the thing was blowing warm air (around 73) on max fan speed and recirculation on. I have included a picture of what the accumulator looked like after that; totally frozen. Back I went to the dealer. I drove it there totally frozen so they could check the pressures.... Low side 15, High side 180 ambient temp of 84 degrees and rising. The Fin temp sensor was showing 70 degrees. What they found was that the fan speed was left on low then the system would not freeze over but anytime the fan speed was increased any higher than the lowest setting it would freeze over. Now they want to try and relocate the fin temp sensor to a colder spot on the evaporator (at their expense). What do you all think of this? Any one have any luck relocating the sensor or do you think it is just low of R134a? I am at my wits end...Please help...Thank you in advance.

Frozen Accumulator...


Screens that were cut out...

mk378 on Thu August 04, 2011 12:25 PM

Usually there is a switch that cuts the compressor off around 25 psi low side. This prevents overcooling the evaporator and ice up.

sevobuck on Thu August 04, 2011 12:36 PM

They said there is only a high side switch.

iceman2555 on Thu August 04, 2011 2:59 PM

There is a temp sensor mounted in the evaporator. Should be accessed thru a small opening/door in the evap case under the glove box. There should be a test for this sensor to determine if it is indeed the fault. Could be in the BCM....but probably the sensor.
Just to know for sure...check the suction line from the evap outlet back to the compressor for a LPCO. If not there...it's in the evap case.

Good luck !!!!

-------------------------
The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

sevobuck on Thu August 04, 2011 3:15 PM

I made the 30 mile trek to my dealer and left it on the lowest fan speed with the recirc on and by the time I made it to dealership, the whole thing was totally ice covered. There goes their theory that it doesn't freeze on the low setting.

sevobuck on Thu August 04, 2011 4:11 PM

Quote
Originally posted by: iceman2555
There is a temp sensor mounted in the evaporator. Should be accessed thru a small opening/door in the evap case under the glove box. There should be a test for this sensor to determine if it is indeed the fault. Could be in the BCM....but probably the sensor.

Just to know for sure...check the suction line from the evap outlet back to the compressor for a LPCO. If not there...it's in the evap case.



Good luck !!!!



There is no BCM on these trucks. What's an LPCO?



Edited: Thu August 04, 2011 at 4:18 PM by sevobuck

iceman2555 on Thu August 04, 2011 4:46 PM

LPCO is Low Pressure Cut Out/Off switch. It's purpose is to prevent exactly the condition you are experiencing. But I think this system utilizes a temp sensor located in the evap core that signal references the BCM for clutch engagment.

-------------------------
The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

sevobuck on Thu August 04, 2011 5:30 PM

You are correct. These trucks utilize a fin temp sensor. That is what they are going to relocate and replace. Hopefully it does the trick.

Edited: Thu August 04, 2011 at 5:33 PM by sevobuck