Fan Clutch and AC woes continue

[scootergmc]

Backstory- 2004.5 HO Cummins owned since new, Smary Jr. level 1, 138,000 (I think) miles, basically a cream puff, no other engine/trans mods that I can recall offhand.

A few years ago the AC stopped being cold. I read Tuesdak's threads and many many others around the internet and this forum, which seem to attribute this issue to some sort of engineering flaw which magically appears somehow after the truck gets older.

Got around to trying to fix it in 2021 which ended up with an OEM fan clutch replacement after discovering refirgerant pressure was blowing the relief. Fan roar briefly came back on the first start and the AC (after recharge) worked again. But never heard the fan again. Didn't take long for the refrigerant to blow out the compressor relief. *sigh*

A few weeks ago it was time to replace the front crank seal so I did that and went ahead and installed another OEM fan clutch (p/n 55056990AC), along with a new pressure transducer just to make sure that wasn't the problem. First start heard the fan clutch roar. Sweet. Maybe it's fixed. Vacuum (yes it held vacuum) and fill the AC. Watch the gauges after fill and it climbed over 400 psi, the fan clutch didn't engage and I shut off the truck. Uninstall Smarty Jr. just in case. No changes. Reinstall Smarty Jr. No changes. No fan clutch codes or any codes for that matter at any point in this history. Still high pressure. Darn.

So I'm using the AC right now as long as I'm going at/over 45-50 mph.

The truck also climbs over 200 (just past the straight up position), maybe 210ish on the temp gauge before the thermostat opens. When the truck was new it would never indicate over 200, even when towing. I do not have a real time scan tool to see the fan speed, but all signs indicate it's not receiving the correct signals from the ECM/PCM, and if I understand correctly there are a few different components which trigger power to the fan, trans temp, engine temp, AC, etc.

As for the factory service manual fan clutch test, it says it should spin free 5 ish turns by hand. My original fan never did that, the 1st OEM replacement never did that, and the new one didn't do that either at install or at any point since. So I'm not sure that's an accurate test. Granted, I do live in a warm climate. I'm somewhat at a loss but I do want to get a scan tool (maybe Snap on or Autel or something like that, I'd like the factory DRB tool but they're pricey) to see what's happening. I just don't want to take it into a dealer for a snipe hunt that may or may not result in "oh, you need another fan clutch" or "oh, your EMC is bad it's going to be $2k..." I'd like to have a better idea of what's going on before I head down that road. I was also told there may be a TSB for my truck for poor fan clutch performance but I haven't found it (Did the TSB index disappear?).

What say those here? Thanks for the assistance again.

 

[Tuesdak]

First start heard the fan clutch roar. Sweet. Maybe it's fixed

Morning Sickness. A clutch fan is either "on" when the engine shut down or the internal ports line up and the working chamber fills up locking the clutch in. It then runs for 2 min after startup. It's uncommon these fans don't have morning sickness for the first 2 min or so after startup. When they don't due to an ECM bug the A/C overheats the condenser and NOTHING in the ECM shuts the A/C off. At times the fan, even on NEW under OEM Warranty in the day, couldn't kick in fast enough.

The manual test procedures for the fan are a bad joke. 15 Min to "Do Something" for the fan = the A/C has overheated and dumped 1/2 it's charge out the emergency high pressure relief valve. Fun fact: it paints the oil filter with A/C oil. However the official fan procedure mentions a fuse and a test of electrical here:

https://www.turbodieselregister.com/threads/fan-clutch-performance-test.261128/

You need something that tells you Fan RPM, PWM % Commanded for the fan, and AC pressure. I can't tell if your system has the ECM commanding the fan to come on, if a fuse is blown to the fan, or if you are simply running into this not so well known defect.

Engineers freezing their butts off in MI and Germany have no reason to extensively test their A/C systems until warranty and Lemon Law costs them enough to "Fix It". They looked into it and couldn't figure it out. In depth below.

https://www.turbodieselregister.com...rams-ecm-defect-opening-the-ac-relief.258779/

One way to help the A/C.

https://www.turbodieselregister.com...thermal-dispersant-on-an-ac-condenser.264486/

 

[Ozymandias]

Was the AC filled by weight or by pressures?

2004.5 has still the Sanden Compressor so it's a whole different system then the 05+ years with the x(forgot its name) compressor.

Mine is still on the factory compressor at 250k, I played around a lot with it to get more cool and even with a severe 50% overcharge it never blew the relief valve.
I do not hear the fan at all starting the engine (AC on), after a longer period of idling it comes on briefly for a couple second and then shut of for a minute or so, Engine hot.

 

[scootergmc]

Was the AC filled by weight or by pressures?

2004.5 has still the Sanden Compressor so it's a whole different system then the 05+ years with the x(forgot its name) compressor.

Mine is still on the factory compressor at 250k, I played around a lot with it to get more cool and even with a severe 50% overcharge it never blew the relief valve.
I do not hear the fan at all starting the engine (AC on), after a longer period of idling it comes on briefly for a couple second and then shut of for a minute or so, Engine hot.

Filled by weight, as prescribed according to the tag under the hood. Bottle on the scale, etc.

 

[AH64ID]

As far as going to 210° before the thermostat opens, you need a new thermostat. Get a genuine Cummins 190° thermostat.

 

[Tuesdak]

As far as going to 210° before the thermostat opens, you need a new thermostat. Get a genuine Cummins 190° thermostat.

I am not sure how the OP's knows the temp the T-Stat opens at. I would suggest it's just the engine temp gauge rising because the engine fan control is completely INOP. When in doubt I don't bother to even test T-Stats anymore because they can randomly stick. X2 on genuine Cummins 190°. However IMO it's clear the fan isn't coming on.

The engine temp running high is only related to the A/C by the engine driven fan. No fan, like a canary in a coal mine, the A/C system overheats and fails first. The condenser is starting to overheat at 160F, 300psig, and 178F is 380 psig on the high side of the A/C system.

Other than checking the fuse, checking for 12V at the fan connector, and then shorting the ECM side of the fan that goes to ground the test procedure isn't that detailed.

I would suggest the focus needs to be on troubleshooting the engine fan electrical. Two fan clutches and both had problems well odds are one may have been good.

@scootergmc Have you checked for codes? Some codes do not turn the Service Engine Soon light on. It would be helpful to know if there are any codes present before you do this test.

Some notes on the test that you can do without expensive tools.

NOTE: The following test may take up to 15 minutes to perform.

The engine should be at normal operating temperature. (All you need is enough time for the fan's morning sickness to stop. Engine temp for this test doesn't matter. The fan will work with the shorted wire regardless of engine temp. After all the fan comes on in two blocks for the A/C demand on a cold engine all the time.)

1. Set the parking brake and verify the transmission is in park or neutral.
2. Set air conditioner (if equipped) and blower fan to OFF.
3. Start and allow engine to reach normal operating temperatures. (All you need is "fan winds down" from morning sickness. Fan kicks out faster IF you rev the cold engine to 1500-2000 RPM.)
4. Stop engine, connect the scan tool and select appropriate model year and engine option.
5. Check for and correct existing DTC's
6. Using Tool 6801 , backprobe pin 1 of the electronically controlled viscous fan drive connector, with the harness connected located at the lower fan shroud to battery ground. (A safety pin to backprobe and a jumper wire will do the job.)

NOTE: The fan drive control coil is energized to 12 volts at this time.

WARNING: A spark may occur when connecting pin to ground. Be sure that no combustible material is in the area.


7. Using the scan tool, verify that DTC 0480 set. If it is not set, verify that a good ground is available. (If you haven't checked for codes this step should set one.)
8. Start the engine.
9. Actuate engine speed to 2000 RPM. (You can work the throttle no need for a tool)
10. Go to the SENSOR screen and observe the fan speed. (You Got Ears? You will hear the fan come up to speed. If so the fan clutch itself is working.)
11. Run the engine at 2000 RPM until the fan speed increases to 1850 RPM or more for 30 seconds.

NOTE: Fan RPM may ramp up slowly.

NOTE: It maybe take 15 minutes before fan speed increases. (IDK maybe in Podunk Alaska at -40F. Normally it will be up to speed in less than 2 min.)
12. The fan speed should be in accordance to the table below.
13. If fan speed does not increase, make sure that the jumper wire has a good connection. If so replace the electronically control viscous fan drive.
14. If the fan speed does increase and there is still a concern, refer to the appropriate Engine Electrical Diagnosis Section to diagnosis the electronically controlled viscous fan drive control circuit.



ELECTRONICALLY CONTROLLED VISCOUS FAN DRIVE SPEEDS
ENGINE RPM FAN RPM (Min)
1000 950
1500 1420
2000 1850
2500 2230

 

[AH64ID]

To clarify, I think his thermostat opening temp and A/C issues are completely unrelated.

 

[scootergmc]

The thermostat is an OEM Cummins 190, replaced once since the truck was new, and the temp gauge behaved as the original prior to this AC/Fan issue. The temp didn't climb as it does now prior to opening, nor did the temp increase when climbing hills, especially unloaded. Right now it reads just under 200 cruising on the freeway, as has always been normal, since the fan isn't required to do much at speed. But if I pull a grade, even unloaded, I'll see over 200 easily. Makes me think the fan isn't receiving the signal to speed up or engage. I guess I could replace the thermostat again, but I don't see the need at this second.

Re codes: Yes, as previously stated, I don't have at present and have never had codes.

As far as the backprobe test, if I understand correctly, I stick the pin in the #1 terminal (park lockout solenoid control according to the manual) on the fan clutch side, the upper right wire (as if looking at the open pin ends with clip up), and jump that directly to battery ground. Fan should fully engage correct?

 

[scootergmc]

To me, it behaves like there's a cracked/broken solder connection on a circuit board somewhere.

 

[AH64ID]

The 190° thermostat cracks at 190°, but isn’t fully open until 207° with a max allowable temp of 225°. The fan isn’t commanded to 100% until 215°, so you aren’t in the fan operation range for ECT.

The reason I think it needs to be replaced is because of how warm it gets on the initial opening, which means it’s wearing out. The fan should have no effect on the ECT for initial opening.

If you’re getting above 200° empty on a grade it’s also an indication of the thermostat being an issue. The fan shouldn’t be doing anything at this point either.

 

[scootergmc]

Ok thanks. Guess I'll get another.

So at what temp is the fan commanded to do anything?

 

[Tuesdak]

So at what temp is the fan commanded to do anything?

Engine as noted above. You would need a scanner or a temp display on say a Smarty as the temp gauge is a guess.

A/C should have the fan on in about 1-2 blocks at 25 MPH with the cab blower on high. I recall 250 psig starts the fan and 300 psig the fan should be on 100%. @AH64ID may know the A/C fan pressures better.

As far as the backprobe test, if I understand correctly, I stick the pin in the #1 terminal (park lockout solenoid control according to the manual) on the fan clutch side, the upper right wire (as if looking at the open pin ends with clip up), and jump that directly to battery ground. Fan should fully engage correct?

Yes. This makes sure the 12V fan control works. No codes could be voltage but not able to carry current say: corroded wire, corroded connector, corroded fuse contacts... Does this year have the TIPM?

 

[scootergmc]

Yes. This makes sure the 12V fan control works. No codes could be voltage but not able to carry current say: corroded wire, corroded connector, corroded fuse contacts... Does this year have the TIPM?

No, it has the what the service manual calls the IPM (fusebox), but not a TIPM.