AC Clutch not engaging

[jghflys]

I read a bit about your testing tool.

FYI, Power probes are good for up to 20 amps for two seconds. 8 amps continuously, 10 amps for 20 minutes and so on. Momentary inrush current rating is much higher. They have an auto reset thermal breaker internal to the instrument. I have used it to test starter solenoids, blower motors, power window motors, lights ..... I get your point though.

 

[petersonj]

@jghflys , that is good information to know. When doing electrical tests, I always like to error on the side of caution. I was mostly concerned with the overall length of the wiring used with the tool, especially not knowing the wire gauge. Some electrical components are more sensitive to voltage drop than others.

Thank you for the comment,

- John

 

[Zoomschwortz]

My Son uses a Power Probe 4 where he works and loves it, so I bit the bullet and bought one.

I wonder how many amps the clutch draws, could it be over 10 amps?
Those wires that power the clutch are pretty thin so I can't imagine it drawing very much amperage.

Thank you both for your help and information.
Ken

 

[petersonj]

I wonder how many amps the clutch draws, could it be over 10 amps?

The AC clutch on my 2nd generation truck is protected by a 10 amp fuse. Your truck would be similar.

- John

 

[sag2]

Power probes are the go to for most professional technicians. The new ones can even do PWM circuits and activate low current computer circuits. We use them at the college for all electrical diagnosis. I saw many technicians using them and thought they were a gimic the tool guy sold them on, but once I purchased one I would not be without it.
As far as the pressures, I would guess the gauges are not accurate, because if it is filled with R-134 the temperature/pressure should be within a couple pounds of the chart assuming there was not engine heat or sun load on the condenser that would raise the ambient temperature of the refrigerant.
Also the TIPM generally does not like to be back few power, so you should only apply power to the compresor with the electrical connector disconnected.
The diagnosis is pretty simple, you had B+ to the compressor. If you had a clean ground the clutch should work. Adding external power and ground to the clutch proves it is bad.

 

[Topzide]

Should hear the clutch click/clunck when energized. Very similar to a relay, only louder due to size. Was the one thing we used to tell people to check on there mowers when deck stopped working. Those PTO clutches had a loud clunck when they got power! Rock Auto has a A/C compressor kits for around $200 or a Denso compressor only for $206. I guess it depends on how in depth you want to go. I've done kit on a Caravan and my 1500. Not to bad as long as you have vacuum pump. 1500 was the worst due to also doing evap. Dash was such a pain to pull and replace! Good luck, glad to hear like the end may be near!

 

[BigPapa]

What’s the air gap on your clutch? Have you attempted to push the plate against the pulley while the magnet is energized?

 

[Zoomschwortz]

20 amps on the PP should have engaged the clutch. No clunk when power was applied.

Haven't physically measured the air gap, but there is a visible clearance, looks like .020"- .030" range.
I didn't push the plate when energized. It was hard enough trying to keep the probe on one terminal without touching the other terminal.

I used the AC less than 2 months ago to defrost the windshield and it worked fine then.

I have seen some surprisingly good prices on kits that include new compressors, but if I can find a new clutch and coil I would rather keep the system sealed and give a new clutch a try.

I believe I figured out why the pressure was high.
Last night in bed I was trying to figure out why the pressure was high and I had that embarrassing DUH moment.

As instructed on Youtube and the intranet, I had the engine running when I checked the pressure.
It was running 15-20 minutes DUH. No doubt the heat from the engine and radiator had to have heated up the R134a.


Any recommendations on where to buy a new clutch and any preference in brand of clutch?

I really want to thank everyone for their help and information
Ken

 

[petersonj]

I believe I figured out why the pressure was high.
Last night in bed I was trying to figure out why the pressure was high and I had that embarrassing DUH moment.

As instructed on Youtube and the intranet, I had the engine running when I checked the pressure.
It was running 15-20 minutes DUH. No doubt the heat from the engine and radiator had to have heated up the R134a.

One of the many variables - I just didn't mention that one. Solar energy can heat the cab as well. Many things influence the actual temperature of the refrigerant at any given moment. That is why I had no real concern regarding the 70 psi at 58°.

Let us know how the repair turns out.

- John

 

[jghflys]

Any recommendations on where to buy a new clutch and any preference in brand of clutch?

Sorry, I only have information on a 2005 with the Denso or Sanden compressors. Maybe someone else can help. FYI my 2005 has a diode in the wiring harness for the clutch circuit according to the manual. I do not know where the diode is. It may be part of the magnet. I found the attached picture. #ad

 

[jghflys]

The results with probe on + side was 0.0 & reversed it was more than 2k - less than 20k
wonder if there is a diode in it.

Looking at your readings, the magnet coil is open. The diodes are wired in parallel with the magnet coil to suppress voltage spikes in the coil when the field collapses when the magnet is deenergized. Reading one way the resistance should be 0.0 ohms, forward bias resistance of the diode. Reading the opposite way, the reading should be coil resistance of about 3 to 4 ohms. A reading of K ohms indicates you are reading the reverse bias resistance of the diode not the lower resistance of the coil.

 

[Ozymandias]

Get a clutch or if you can afford it change the whole compressor.

 

[CVR222NV]

I got mine from this outfit in Tucson, AZ:

Dodge Ram Diesel Clutch Coil CC-401DLN (shopcenturyautoair.com)

 

[Ozymandias]

I got mine from this outfit in Tucson, AZ:

Dodge Ram Diesel Clutch Coil CC-401DLN (shopcenturyautoair.com)

That's a good deal, I'd buy that.

 

[Zoomschwortz]

I ended up ordering a Carbole clutch & coil with lifetime warranty.
If I'm tearing it apart I might as well replace the clutch and coil.

Really are not a lot of options for clutch and coil packages, but it appears that just a few years ago there were no options, so I guess I can't complain.

Supposed to be here Friday, I will let you know how it turned out.
Thanks to everyone that helped

 

[Tuesdak]

Can you post a picture of the clutch? Otherwise is the paint burned off, blue metal, or melted magnet look?

If the clutch has been slipping it will burn up the magnet coil. Some may have a one time thermal fuse in them.

The clutch slipping can be from a shaft seal oil leak, compressor locking up, clutch wear. A slipping clutch is likely to hurt the shaft seal.

 

[Zoomschwortz]

Can you post a picture of the clutch? Otherwise is the paint burned off, blue metal, or melted magnet look?

If the clutch has been slipping it will burn up the magnet coil. Some may have a one time thermal fuse in them.

The clutch slipping can be from a shaft seal oil leak, compressor locking up, clutch wear. A slipping clutch is likely to hurt the shaft seal.

Thank you for this information.
I am waiting for the new clutch/coil to arrive so I haven't removed the old one from the truck yet.
I will take pictures and post them when I get it off the truck.

Thanks to everyone for their information and help, hope you all have a safe and fantastic 4th!
Take care
Ken

 

[Zoomschwortz]

I installed the coil/clutch yesterday. The coil was literally cooked and the clutch assembly fell apart in my hands.

After installation last night, outside temperature was about 56F and AC Temp was just under 40F, so it is now working good.

I am wanting to connect the manifold gauge set and see what my pressures are while the engine/AC are running.
Does anyone have a R134a chart that shows expected pressure vs ambient temperature?

Any ideas for what would have cooked the coil? It is literally flaking apart when I touch it.
There was black, sooty residue inside the coil, clutch & pulley assembly and while pulley bearing rotation on the original pulley wasn't as easy as it is on the new pulley, it still turns fairly well with 2 fingers. It appears that the black residue is from the coil.

Thanks in advance for any help or information.
Ken

 

[jghflys]

I use the procedure and the bands below in the chart to add to existing charge. I get satisfactory results without evacuating the system.

A/C PERFORMANCE TEST

WARNING: REFER TO THE APPLICABLE WARNINGS AND CAUTIONS FOR THIS SYSTEM BEFORE PERFORMING THE FOLLOWING OPERATION. FAILURE TO FOLLOW THE WARNINGS AND CAUTIONS COULD RESULT IN POSSIBLE PERSONAL INJURY OR DEATH .

NOTE: When connecting the service equipment coupling to the line fitting, verify that the valve of the coupling is fully closed. This will reduce the amount of effort required to make the connection.

1. Perform the A/C System Performance Test found within the HVAC System Test. If no diagnostic trouble codes (DTCs) are found in the A/C-heater control or the powertrain control module (PCM), go to Step 2. If any DTCs are found, repair as required, then proceed to Step 2.
2. Connect a tachometer and a manifold gauge set.
3. Set the A/C-heater control to the Recirculation mode (max-A/C) position, the temperature control to the full cool position, and the blower motor control to the highest speed position.
4. Start the engine and hold the idle at 1,000 rpm with the compressor clutch engaged. If the A/C compressor does not engage, see the A/C Diagnosis chart.
5. The engine should be at operating temperature, the doors should be closed and the windows opened.
6. Insert a thermometer in the driver side center panel outlet and operate the A/C system until it stabilizes.

NOTE: The A/C compressor clutch may cycle, depending upon the ambient temperature and humidity.If the clutch cycles, use the readings obtained before the clutch disengaged.
#ad



Performance Temperature And Pressure

 

[Zoomschwortz]

I use the procedure and the bands below in the chart to add to existing charge. I get satisfactory results without evacuating the system.

A/C PERFORMANCE TEST

WARNING: REFER TO THE APPLICABLE WARNINGS AND CAUTIONS FOR THIS SYSTEM BEFORE PERFORMING THE FOLLOWING OPERATION. FAILURE TO FOLLOW THE WARNINGS AND CAUTIONS COULD RESULT IN POSSIBLE PERSONAL INJURY OR DEATH .

NOTE: When connecting the service equipment coupling to the line fitting, verify that the valve of the coupling is fully closed. This will reduce the amount of effort required to make the connection.

1. Perform the A/C System Performance Test found within the HVAC System Test. If no diagnostic trouble codes (DTCs) are found in the A/C-heater control or the powertrain control module (PCM), go to Step 2. If any DTCs are found, repair as required, then proceed to Step 2.
2. Connect a tachometer and a manifold gauge set.
3. Set the A/C-heater control to the Recirculation mode (max-A/C) position, the temperature control to the full cool position, and the blower motor control to the highest speed position.
4. Start the engine and hold the idle at 1,000 rpm with the compressor clutch engaged. If the A/C compressor does not engage, see the A/C Diagnosis chart.
5. The engine should be at operating temperature, the doors should be closed and the windows opened.
6. Insert a thermometer in the driver side center panel outlet and operate the A/C system until it stabilizes.

NOTE: The A/C compressor clutch may cycle, depending upon the ambient temperature and humidity.If the clutch cycles, use the readings obtained before the clutch disengaged.
#ad



Performance Temperature And Pressure

Thank you for this information, I will check to see where my system is at.
Ken