07 A/C Moaning noise

[RussellSullivan]

2007 5.9 48Re 4wd 275K miles Stock except Banks Exhaust Brake

After a long very hot day of travel I noticed the A/C was moaning. Still cooling the cab nicely with 41 degree air. Not wailing or grinding, just a low moan easily heard from in the cab. Too much engine noise to hear when listening near the engine.
Only moaned while the compressor was engaged. Nope, not the fan. I figured the compressor was bad so I
evacuated the system and took it apart. Liquid (orifice) line was full of aluminum flakes. Compressor cylinders were all lightly scored.
I flushed the evaporator and the pressure and suction lines. Then replaced the compressor (with 5 oz PAG 46 oil), condenser, liquid line and accumulator (with 2 oz oil). Pulled a vaccume for 50 minutes and after recharging with .850 KG 134a it was blowing 40 degrees at outside temp of 85 degrees.
Works great, but it still moans whenever the compressor turns on.
I'm at a loss as to what is causing this noise. Hope someone can help.
Thanks,
Russell

 

[Tuesdak]

Check every bearing on the fan belt path. Spin by hand with belt off.

What is the high side pressure? How old is the fan clutch?

 

[RussellSullivan]

Check every bearing on the fan belt path. Spin by hand with belt off.

What is the high side pressure? How old is the fan clutch?

Check every bearing on the fan belt path. Spin by hand with belt off.

What is the high side pressure? How old is the fan clutch?

All the old parts had about 100K miles on them.
I forget to mention that I did remove the belt and spin all the bearings run by it. The fan bearing and the alternator bearing were bad so I replaced them. Also replaced the H20 pump, tensioner and idler pulley bearing.
The power steering was smooth as was the Banks vacuum pump.
Even with all the new parts including compressor the noise continues.
The low side pressure varied up and down from 35 to 55. The high side remained below 180.

 

[PMedina]

I recently spent considerable time trying to track down what I was certain was a bad bearing. It made more noise when the compressor was running. The nut on the AC clutch was backed out and the clutch was quite loose. I tightened it up and the noise did not go away. The alternator bearings sounded really dry and a bit rough. I replaced it with a new Bosch unit and the noise was still there. The idler pulley on the tensioner turned smoothly but it has radial play relative to the arm. A new tensioner didn't fix it. All other accessory bearings seemed fine. I was pulling my hair out trying to figure it out and finally took it to a trusted mechanic. He called me and said he was certain it was the belt. I've never heard a belt make that kind of noise. It was one of the premium green Gates belts with less than 75k miles. He replaced with a standard belt and the noise is completely gone. Maybe it’s your belt. I’m guessing, while troubleshooting, that had I squirted the belt with water when running I may have been able to identify it as the problem. Good luck

 

[RussellSullivan]

I recently spent considerable time trying to track down what I was certain was a bad bearing. It made more noise when the compressor was running. The nut on the AC clutch was backed out and the clutch was quite loose. I tightened it up and the noise did not go away. The alternator bearings sounded really dry and a bit rough. I replaced it with a new Bosch unit and the noise was still there. The idler pulley on the tensioner turned smoothly but it has radial play relative to the arm. A new tensioner didn't fix it. All other accessory bearings seemed fine. I was pulling my hair out trying to figure it out and finally took it to a trusted mechanic. He called me and said he was certain it was the belt. I've never heard a belt make that kind of noise. It was one of the premium green Gates belts with less than 75k miles. He replaced with a standard belt and the noise is completely gone. Maybe it’s your belt. I’m guessing, while troubleshooting, that had I squirted the belt with water when running I may have been able to identify it as the problem. Good luck

Thank You, I’ll order the new belt and reply soon hopefully with positive news. R

 

[RussellSullivan]

Thank You, I’ll order the new belt and reply soon hopefully with positive news. R

Well, I had high hopes that the new belt would solve the problem. Unfortunately it did not. Tomorrow I will seek the expertise of a couple of auto shop owners in town. And hope for a remedy.

 

[RussellSullivan]

Well, I had high hopes that the new belt would solve the problem. Unfortunately it did not. Tomorrow I will seek the expertise of a couple of auto shop owners in town. And hope for a remedy.

 

[RussellSullivan]

Well, the folks in town didn’t know.
The moaning, now more like a whooooing at higher RPMs is more pronounced especially at around 1500 RPMs. I can feel the vibrations as the engine drops a hundred RPMs and the noise begins when the AC cycles on. Not good.
Is it possible that faulty electronics related to the fan clutch are causing the fan to engage at the same time as the AC?
Thanks

 

[Tuesdak]

Time to look at A/C line placement and see if one is vibrating on something. You can do this by feel although gloves/pot holders are needed on the high side line from the compressor.

What brand of compressor and from where?

Because fiction has to be plausible and truth does not: You can also look into the power steering and hydroboost system. My 2003 had an updated line, with a weight on one of the lines, to stop noise from the P/S system. IDK if 2004 also has a revised P/S line.

 

[RussellSullivan]

There is minor vibration on the pressure line. It is routed properly, held in by plastic clips that separate it from any metal surfaces.
When I flush the evaporator I notice more resistance when blowing flush solution in through the pressure side than the suction side. Should there be a difference? It goes through either direction ok and comes out clean. Just more resistance through the pressure side. 80 psi.
The compressor is a new Four Seasons from NAPA.

 

[Tuesdak]

Post a video of the sound?

It's either Normal, indicating high head pressure, or another compressor failure.

Has the outside temperature been higher than usual with the heat waves?

At 1500 RPM what is the high side pressure? What is the outside temperature?

Does the engine fan come on before two blocks at 25 MPH with the A/C turned on from a cold start?

Assuming the noise is a problem, Vs. Normal I would start with the cooling fan clutch and making sure there isn't a bunch of debris clogging the cooling stack. Is the fan clutch over 5 years old? They get slow to respond and loose 200 RPM per year. The Electronics can overcome some of the RPM loss, but, the response time they can't. More or less replace a fan clutch that's 5 years old as the A/C system is the first to overheat and burn up from a weak fan clutch while the engine running at a higher temperature doesn't care yet. The heat from the cab has to go somewhere after all.

Next I would look at the orface tube (line) again for metal. It's possible debris remained in the system including an internally corroded evaporator. These systems with a low charge can run the low side in a vacuum and draw in moisture that will corrode the evaporator.

I would use a OEM compressor, Genuine Denso for your year. I have had way too many problems with aftermarket compressors. Four Seizeasons I do hold in a better regard than other stuff. Clearly the bar ain't that high.

What compressor came off? OEM? Maybe the aftermarket compressor is a nosier design.

 

[RussellSullivan]

Thanks for the info and questions.
The outside temp is most always over 100 this time of year. Normal, with low humidity.
This morning the AC high side pressure was 275 psi at 1500 rpm at 93 degrees ambient temp.
It stayed about the same to 2200 rpm which is as high as I went.
I can't tell about the engine fan coming on before two blocks on a cold start because
its a 1/3 mile down a rough dirt road before I get to the pavement and can get going.
The fan clutch is clean and debris free. Its seven years old and has 38,000 miles on it.
The old compressor was also a Four Seasons.
Am working with the TDR to get a video uploaded. It may be a while.
Will also have to budget for a new Mopar fan clutch and Denso compressor plus related parts.
Any insight will be much appreciated.

 

[Tuesdak]

It stayed about the same to 2200 rpm which is as high as I went.

This is windows closed, blower on high, holding just 1500 RPM, watching the high side pressure, and verifying the fan comes on. No need to rev higher. Sometimes the compressor clutch will cycle as the system gets the evap near freezing. I generally don't do this longer than a min or two.

If anything this is appearing to be normal with the possibility noise is transmitting through something it wasn't before. (Without benefit of hearing the noise myself.) I am assuming the fan is coming on by the high side pressure readings. I would run the system and not worry about it at this time. When budget allows I would prioritize putting a fan clutch on it.

 

[RussellSullivan]

Still working with TDR to get the video uploaded.
I will order the new fan clutch and the Denso compressor.
Thanks to Tuesdak and PMedina for your help.

 

[RussellSullivan]

I had to open a you tube account so I could upload the video. That route didn’t work either. Aaargg!!
I’d rather replace a u joint.

 

[RussellSullivan]

I had to open a you tube account so I could upload the video. That route didn’t work either. Aaargg!!
I’d rather replace a u joint.

Well, I replaced the fan clutch (Mopar) and it comes on more often than the old one. Im sure the truck will be "happier" with the change.
After evacuating the A/C system and flushing it thoroughly (did the evaporator four times both directions) and installing a new Denso compressor, plus 46 oil and R134a, I still have the same moaning noise.
Only happens at an idle now.
Reading about other A/C systems I learned that a compromised evaporator can cause
moaning or humming noises.
Since all other A/C parts are new and everything that turns or moves on the front of the engine has been replaced
I will now tackle the evaporator.
I have the service manual and have reviewed all the steps to remove the dash. I once removed the dash in my 2001 5.9 so I am generall familiar with the procedure.
Can this evaporator be accessed with the dash just tipped and leaning on the seats or is complete removal necessary?
Any pointers would be greatly appreciated.
thanks

 

[Ozymandias]

From what I've seen you lay down the dash on the two front seats or take it out entirely. Taking it out isn't that big of a deal on these newer trucks then it was in the older days.

 

[Tuesdak]

Any pointers would be greatly appreciated.

When I had the dash out on my 2003 (Load Parts Cannon) I replaced the heater core (MOPAR) and upgraded all the failure prone doors with Heater Treater. I was chasing the AC design defect that vents the system out the safety relief valve and was guessing it had an evaporator leak at the time. It also needed a new wiring harness for the blower motor and it's resistor. (Bad hot spot at the blower resistor plug and at the motor connector.)

 

[eimhear]

If the compressor mounts or brackets aren’t secured tightly, or if there’s slight play, it can cause a moaning or humming noise. Double-check the mounting bolts and any rubber bushings. Sometimes, when the A/C system operates under pressure, the refrigerant lines can resonate or vibrate slightly, which could cause a moaning sound. Ensure the lines are securely clamped and spaced to minimize vibrations. And also check the bearings.

 

[tjm]

When I had the dash out on my 2003 (Load Parts Cannon) I replaced the heater core (MOPAR) and upgraded all the failure prone doors with Heater Treater. I was chasing the AC design defect that vents the system out the safety relief valve and was guessing it had an evaporator leak at the time. It also needed a new wiring harness for the blower motor and it's resistor. (Bad hot spot at the blower resistor plug and at the motor connector.)

second this. did the same when i replaced the evaporator in my 2005