A/C Compressor Clutch - Diagnosing

[GordDavey]

Thanks Gord,
both ends of the fuse have 0v and I even put a new fuse just to be sure. I will try to check the pressure transducer tomorrow. I did connect the gauges and the low pressure was on 60psi and the high pressure was 20psi with the clutch disengage. I am not sure if that is OK but at least I know there is freon in the system. what voltage should I get from testing the pressure transducer to be correct? Where do I go if the pressure transducer checks OK?
Thanks.

Rafael
I’m sorry I don’t remember the pressure values. But yours sounds low to me. Others will know the pressures.

 

[GordDavey]

Thanks Gord,
both ends of the fuse have 0v and I even put a new fuse just to be sure. I will try to check the pressure transducer tomorrow. I did connect the gauges and the low pressure was on 60psi and the high pressure was 20psi with the clutch disengage. I am not sure if that is OK but at least I know there is freon in the system. what voltage should I get from testing the pressure transducer to be correct? Where do I go if the pressure transducer checks OK?
Thanks.

Rafael. From what I’ve read depending on the surrounding air temp the high side should be over 100. There are charts on the net with pressures for low and high side based on ambient air temp and what to look at when the pressures are wrong. If you really are only getting 20psi on the high side. Then it’s likely the transducer is reporting that pressure and the ECM is refusing to power the clutch. I’m no AC expert so this is we’re my knowledge ends on this one.

 

[Rafael Blanco]

I forgot to mentioned that the condenser fan does not come on either. Is it possible that the solenoid in the compressor is bad and causes the problem? I checked the connector and was all coated with white type corrosion, I cleaned it the best I could but did not make any difference.

 

[crash68]

If the compressor is not running, both the high side and low side pressure should be the same, if not there a problem. Also the refrigerant pressure should be roughly the same as the ambient temperature 65°F = 65 psi

 

[Rafael Blanco]

Thank you guys!
Today when I was coming back home from work the AC worked. I was playing with the headlights switch and I started to feel nice cold air then I stop to visually check and sure enough the compressor was working. When I got home I was checking things under the hood and the refrigerant pressure was fine (pressure according to chart observed in gauges). However, two things I observed were the condenser fan was not working though the AC was on and the low side AC hose only felt a little cold and not super cold as you would expect. Now I am totally baffled because I don't know how the multi-displacement solenoid in the AC compressor affects the way the AC works in comparison to other cars without that solenoid. I hope it works tomorrow but even if it does, what system might be interfering with the AC? The headlights seem like a good candidate but I don't really know how or what to start checking from here.

 

[GordDavey]

Rafael, Well you did mention that fuse 62 was blown and you replaced it. There could be a short in the wiring somewhere which caused that fuse to blow, or an issue with the PDC that caused that fuse to blow. But the wire is just ECM to PDC, then PDC to AC compressor.

I don't know what conditions cause the condenser fan to run or not. But there are only a few pieces to the entire AC system. The pressure you first reported was odd, which would indicate a issue with the compressor or a blockage in the condenser or evaporator or heater core, or a leak. I'd say try to eliminate the electrical side by making sure connectors and contacts are clean, grounds all work and voltage is correct with the truck on Max A/C. Test what electrical you can like powering the condenser fan, just like you did the clutch and eliminate the electrical. After all that appears OK, I would get leak test and validate the pressure. If nothing is found, then I would suggest a new AC compressor. But as I've said before I'm not a pro, just a DIY'er. But that's my advice.

 

[Rafael Blanco]

Ok, due to my inability to find the problem took the truck to a professional AC shop and they diagnosed the the problem to be the compressor built in solenoid. I was wondering if that is a part that can be purchased separately from the compressor. I made a quick search and could not find it. Any ideas?

 

[RedSRT4Me]

There is an electronic controlled solenoid in the compressor. It is what varies the displacement of the compressor.

Connector C1 should have 12V and ground. C2 will have ground and a pulse width modulated circuit. How much voltage there will be on the circuit depends on demand of the system.

Man you are a wealth of knowledge.

I need 24 hours with an employee computer and I'll be able to find every FCA question I've ever had.

 

[RedSRT4Me]

On my 2015 I've gone through 2 A/C compressors. The clutch both times was the culprit but it was probably more beneficial to the dealer to just replace the whole thing.

The air would continue to blow ambient or hot just never cold. That tells me right away the clutch is not engaging to compress the air. I could visibly see the clutch not engaging when it was being commanded to.

I can fix just about anything on my vehicles but for some reason A/C is my kryptonite.

 

[RedSRT4Me]

Ok, due to my inability to find the problem took the truck to a professional AC shop and they diagnosed the the problem to be the compressor built in solenoid. I was wondering if that is a part that can be purchased separately from the compressor. I made a quick search and could not find it. Any ideas?

Based off my research you have to buy it as a unit. Trying to find AC parts for 15 and newer is like pulling teeth.

Not sure if the dealer was making extra on the side but each of my A/C failures required replacement of the compressor.

 

[Rafael Blanco]

SOLVED

The problem was the multi-displacement solenoid in the compressor. That solenoid is not sold separately, not even the dealer, so I bought a used compressor from a 2017 Ram for $75 and swapped with mine and I have nice cold air again.

Thanks all for the suggestions and help!

 

[RedSRT4Me]

SOLVED

The problem was the multi-displacement solenoid in the compressor. That solenoid is not sold separately, not even the dealer, so I bought a used compressor from a 2017 Ram for $75 and swapped with mine and I have nice cold air again.

Thanks all for the suggestions and help!

Makes perfect sense why I've had the compressor replaced twice now under warranty.

 

[Jwrigh12]

Holy dead thread revival Batman!

Sorry...but this thread fit with where I'm at. So I have a similar issue. One day, about two months ago, the ac quit blowing cold in my 2014. (5.7 Hemi, Lonestar) didn't do anything for a while, as it kinda had to be on the back burner.

I'm finally getting around to working on it, and here's where I'm at:

Took it to a shop to have the refrigerant toppd up, they did, but said the compressor would no longer engage. Wanted 1900 to replace the compressor. Told them to remove all they added, and I'd deal with it later. At this point, the system is empty

Came back, started doing some research, and found this thread.

-Tested ground to C1? And it's good.
-Manually jumped the compressor clutch and it seems good (not sure how much travel there is supposed to be. Mine has a mm or two when engaged/disengaged)
-fuse looks good in 62... but with no refrigerant in the system, I dont think there would be a voltage there, correct?

Trying to keep tracing the problem, but not sure where to go from here. Any help would be greatly appreciated!! @GordDavey

 

[Swamptech]

There is a clutch control wire in the (Module PowerTrain control) (typically I call it ECM for Engine Computer), a wire Light Blue and Orange goes from connector C1 (Black) pin 79 on the ECM to the Fuse box (PDC) Connector 3 (black) pin 10.

The A/C Pressure Transducer is also part of the Clutch Control circuit, its a smallish sensor in the AC tubing not far from the fill openings. It has 3 wires, ground, 5v and pressure signal. You can put a voltmeter to ground and the pressure signal and you can see how much pressure it is sending, 1v=100psi, 1.5=150psi, 5v=500psi. This sensor can be replaced without draining the system.

So, if your A/C Pressure is too low or the sensor is bad, then the ECM will not allow the clutch to get voltage, which means 0v at fuse 62.

Yeah this isn’t right. I have 5.5 volts with no refrigerant in it. So replaced everything in the refrigerant systen . Still nothing. I’m sure nobody knows how to fix theseRam trucks they just quote theory. All of these threads are years old. And there’s a million of them. Apparently these aren’t breaking with anyone else. $4,000 later in just parts and I’m certain not even Chrysler knows how they’re made.

 

[14ram1500eco]

Let me know if your truck is Gas or Diesel (engine size too), and what type of Heating System you have (manual or automatic). I have the 2014 wiring diagram, and while the A/C is basically the same for all the different types, there are differences in wire colors. I can send you a piece of the wiring diagram dealing with the A/C.
The A/C clutch itself has two wires, ground and power. You can disconnect the clutch wire and jump them to ground and power at the battery. You won't hurt it, its designed to take 12v. Put the ground on, then touch the power wire to positive on the battery and you should see the clutch move in and out. If it doesn't move, double check your connections, if it still doesn't move then the clutch is bad. If it does move properly, then you can trace it further.

The Relay they refer to is built into the circuit board in the PDC and cannot be replaced separately as far as I know.

The heater module, which depending on the heating type (manual or automatic) will either be a small back box at the far right side of the dash behind the right end dash panel, or will be part of the heating circuit on the back of the controls in the center console (manual). It has a wire which which goes to the A/C clutch should be Light Blue with a White stripe, this wire simply sends 12v when the heating module wants the AC Clutch to engage.

The engine computer (PCM) deals with the AC Compressor control, that wire goes from the PCM to the PDC (fuse box) to supply power to the relay which is part of the circuit board in the PDC. Power comes out the relay thru fuse 62 and down to the back of the AC Compressor, you should get 12v at the AC Compress connector when the truck wants the AC to run. If you get 12v on the Dark Blue with Yellow stripe wire on the back of the AC Compressor when the truck calls for the AC to be on, then it is OK.

You should ensure both black wires in the AC Compressor and AC Clutch connectors get a good ground. Make sure the AC is on and check the power wires for 12v and see which is not right. Depending on what you get, it will point to what the problem is. For the AC Clutch it will be one of: a bad clutch, or a bad power wire or a bad ground or a bad heater module. If the problem is the AC Compressor values, then it could be a bad compressor, bad PCM, bad PDC or power / ground wiring.

where is the wiring ran. I am having the same issue with no continuity on the c1 wire. I have continuity on the c2. I may be wrong but appears to run over to the passenger side of the truck