New Member. Looking for a little help with this stupid Ram AC System.
2006 Ram 3500 MegaCab 5.9L Cummins

AC Stopped working. If I used my Bully Dog Power Pup to change programing levels between Stock and Tow the Bully Dog would tell me there were no codes. But asked if I wanted to clear DTCs. I selected YES and then the AC would work again just fine for a few days. Then stop working again.

Researched and read about the know issue with the AC Coil failures. Checked the coil and got 2ohm reading. But I did not think to check the AMP draw.
I replaced the entire AC Clutch, Pulley, and Coil.

Used the Power Pup to clear any codes (even though it said no codes were found) and the AC worked great again for a few days.

Now the AC is not working again. Programmer again says no codes but tried clearing them anyways. But it did not fix the issue this time.

So started troubleshooting.
Checked new Coil and Compressor by bypassing the TIPM.
New Coil reads 4ohms. And inline AMP reading when engaged in 2.905 to 3.02AMP draw. AC works great. Gets cold when bypassing the TIPM and applying 12v direct to coil. Suction line pressure with the clutch engaged is 34PSI @ 74F with 54% Humidity. I do not have the right adapter to check the High Side. The condenser fan does come on to cool the condenser.

Checked for voltage at the plug leading to the Coil.
With Snowflake switch OFF.
Yellow indicator light is OFF
At the compressor coil plug.
Blue Wire / yellow stripe 12vDC
Black Wide Continuity to Ground.

With Snowflake switch ON.
Yellow indicator light is ON
At the compressor coil plug.
Blue Wire / yellow stripe 12vDC
Black Wide Continuity to Ground.

With Snowflake switch OFF.
Yellow indicator light is OFF
Selector Switch to Defrost Mode
At the compressor coil plug.
Blue Wire / yellow stripe 12vDC
Black Wide Continuity to Ground.

I am always seeing 12V and ground at the compressor plug. Yet the AC does not engage.

Help...

 

Ac clutch relay going bad?

 

In a 2006-2007 there is no Clutch Relay. It is controlled by an internal circut inside the TIPM. No relay to replace.

 

Not 100% sure if these apply TSB 18-005-6a and 6b

 

Hey Aaron: been looking for you to come back and bring us up to date.

Did the new clutch go bad?


Puzzling why it worked by bypassing the TIPM with 12v , and not with 12v from the TIPM.

Did you find out why the constant 12 volts to the clutch?

Now, the ECM does tell the TIPM to turn the clutch on, so either one could be causing it.

I have the manual if you need any help.

 

I got it fixed. I had already replaced the clutch and Coil.

I was getting 12v at the coil plug but no amps. Voltage would fail and drop to 0 under even a small LED load. So no way to trigger a 12v Relay at the coil plug.

Traced it back to the TIPM and found the signal wire from the PCM. Light Blue / Orange wire on C2 Plug Pin 10.

PCM was sending the control signal just fine. Looks like the High Driver inside the TIPM has fried from the Coil pulling 6amps before I replaced it.

I bypassed the TIPM.
Wired the Signal Wire from the PCM to a standard 12v relay setup for Ground Signal Trigger with a 5amp fuse inline, isolated the AC Coil Output wire from the TIPM found on plug C9 Pin 3 Dark Blue/Yellow wire, and fed 12v power via the relay.

Simple solution and a $20 fix too an $800 problem. As long as you understand electronics.

AC works great again. Stupid Engineers..... Over complicating a simple control circuit. Why use a $7 relay when you can build in failure and charge $800 for a replacement TIPM>
Took ab out 30 mins to actually fix the problem . After spending 6 hours troubleshooting it.

 

Glad you worked it out. You are one of the few who understand electronics enough to come up with a workaround.
You get the MacGuyver Award
One question tho, about the TIPM wire you disconnected. My manual says that wire on C7-7 is the 5 volt supply to the AC Pressure Sensor. The control for the clutch should be on C9-3, a DARK BLUE/YELLOW wire.

 

Yep you are right. That was a Typo. I was writing my response from my cell phone in the dark and trying to look at my Connector Pin out sheets. I referenced the wrong connector and pin. Should have read Connector C9 Pin 3 DarkBlue/YL.

Prior Post edited to correct the Plug Pin reference. Dont want to confuse anyone who may also have the same problem.