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Ask -Brad- Your Own Question
-Brad-
-Brad-, Dodge Dealership Tech
Category: Dodge
Satisfied Customers: 6958
Experience:  16 Yrs Chrysler/Dodge Technician. ASE Master Certified(L-1)
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I have a 2007 Ram 2500 with 5.9 Cummins and 48Re trans. 4x4.

Customer Question

Hi,
I have a 2007 Ram 2500 with 5.9 Cummins and 48Re trans. 4x4. 125000 miles. When I bought the truck the AC compressor would often make a short GRRK when being engaged for the first time each day. I replaced the compressor and recharged the system and all was fine for about 100,000 miles. The compressor started leaking clean clear oil (just a drop or two).
I flushed the system and replaced the compressor, orifice tube and accumulator. And recharged the system. The GRRK noise is back occasionally on start up. Now the low side pressure fluctuates from 25 to 48 PSI and the high side pressure fluctuates from 150 to 190 PSI. And the radiator fan turns on and off every minute or so when the AC is running even though the engine temp is normal (less than 195). The air temperature at the center dash vent stays about 42 degrees at all fan settings with outside air temp of 80 to 100 degrees and low relative humidity (16%). Is this problem related to a clogged orifice tube, a bad refrigerant temp sensor, a bad coolant temp sensor? All three? Or some other problem.
Hope you can help,
Thanks
Russell
Submitted: 1 year ago.
Category: Dodge
Expert:  -Brad- replied 1 year ago.

Good evening and welcome to JustAnswer!!

Russell I just had a 07 in my stall last week for a failed compressor in which I had to flush the condenser 3x and the evaporator 2x just to get all the debris out. When you replace the compressor did you see any debris in the lines? Also when you replace the orface tube did you happen to cut it out the line to see if it had any metal on it? How much freon did you put in, it takes 1Lb 14Oz to fill it. If everything checks out then the next step would be to connnect a scantool and see exactly what your evaporator temp is, and if it's around 32 then you have a blend door issue in the dash... Have you checked any of the doors to see if they are operating correctly?

Talk soon,

Brad

Customer: replied 1 year ago.
Hi,
Thanks for the quick response.
When I replaced the compressor there was no contamination or debris in the evaporator or condenser. I flushed both twice. Everything was clean.
The blend doors all function properly. I pulled a vacuum for an hour and recharged the system with 30 oz 134a refrigerant.
There is no scan tool available out here in the middle of nowhere so we will have to proceed without. Will test drive the truck on Wednesday and let you know the results.
Thanks
R
Expert:  -Brad- replied 1 year ago.

You are very welcome...

Glad I could help and thank you for the positive rating,

Brad

Customer: replied 1 year ago.
Hi ,
Test drove the truck today. Outside temperature 60 degrees F. The radiator fan still cycles on and off about every minute or so when cruising at highway speeds (55-65 mph) when the AC is on even though the engine temperature is lower than 195.
Does not cycle on and off when AC is off. Low side pressure is 25 to 45 and high side is 140 to 165. Could this be the result of a bad refrigerant temp sensor or bad coolant temp sensor. My service manual doesn't have any specs for ohm meter tests
for these sensors. Can you provide them?
Thanks
R
Expert:  -Brad- replied 1 year ago.

I re-read your question and is your only issue the fan cycling or the a/c nt being cool enough.. By the performance test I attached it sounds like it's ok besides the constant cycling of the fan..

Let me know,

Brad

Customer: replied 1 year ago.
thanks. I am trying to figure out why the radiator fan cycles on and off every minute or so when at highway speeds
with the AC on but not with the AC off. This happens both in hot weather and cool weather and was not noticeable until I recently replaced the AC components mentioned above.
R
Expert:  -Brad- replied 1 year ago.

Try disconnecting the high pressure switch and see if it quits, and if so replace the switch. And if it cycles with it disconnected you will need a scantool to monitor the requested and actual to see if the ECM is commanding it off/on or if the fan clutch is doing it on it's own.

I hope this helps, and thank you for the positive rating.

Brad

Customer: replied 1 year ago.
Would that be the pressure transducer located on the back side of the compressor?
Thanks
R
Customer: replied 1 year ago.
Would that be the pressure transducer located on the back side of the compressor fittings?
Expert:  -Brad- replied 1 year ago.

The switch on the compressor would be the low, the high is near the condenser on the high side discharge line.