Strange A/C Problem

If it's about Power Wagons, all generations, this is where it'll go. This is the original PWR Forum Power Wagon Technical Discussion Section. And this includes everything that doesn’t fit in any one of the other categories related to the truck goes here!
Ducky's Dad
1000_Posts
1000_Posts
Posts: 1489
Joined: Thu May 24, 2012 10:55 pm

Re: Strange A/C Problem

Post by Ducky's Dad » Wed Sep 19, 2018 11:25 pm

Either the A/C problem is getting worse or I'm learning to manipulate temperature by throttle modulation. Got it to heat up in town today on a "normal" drive. Anyway, stopped by the shop to kick ideas around with the mechanic and he slipped a feeler gauge in the compressor clutch just to check it. Measured at .025" and the spec for this truck is .016"-.024". Current theory is that the compressor coil may be getting weak and that extra play in the clutch may prevent it from engaging. Looking for a compressor shim kit tomorrow to try to bring it back into spec. Will also try to rig a bracket to hold an old iPhone camera pointed at the compressor to record whether it's disengaging when it shouldn't.

User avatar
Retired BLM Rig
500_Posts
500_Posts
Posts: 799
Joined: Sun Jan 31, 2016 6:51 pm
Model Year: 2008
Location: San Clemente, Ca.

Re: Strange A/C Problem

Post by Retired BLM Rig » Thu Sep 20, 2018 1:40 am

I haven't had to do that on a Dodge yet but I've done it a couple of times on Fords.
The Ford actually has one or two shims behind the clutch hub already and you just remove one of the shims to tighten up the clearance. Maybe it's the same on our trucks. It's worth a try! :popcorn:

User avatar
Bill2014
1000_Posts
1000_Posts
Posts: 1224
Joined: Fri May 09, 2014 9:03 pm
Model Year: 2014
Location: Northern NY

Re: Strange A/C Problem

Post by Bill2014 » Thu Sep 20, 2018 7:59 am

Ducky's Dad wrote:
Wed Sep 19, 2018 11:25 pm
... Will also try to rig a bracket to hold an old iPhone camera pointed at the compressor to record whether it's disengaging when it shouldn't.
That's the ticket!
2014 Power Wagon Laramie
Titan V5 2.5" Receiver Pintle Hook
Warn wireless winch controller
.188" DOM White Knuckle Rock Sliders
Locker Bypass & Nanny Kill Switch

Moab 2006

Ducky's Dad
1000_Posts
1000_Posts
Posts: 1489
Joined: Thu May 24, 2012 10:55 pm

Re: Strange A/C Problem

Post by Ducky's Dad » Thu Sep 20, 2018 1:18 pm

The Ford actually has one or two shims behind the clutch hub already and you just remove one of the shims to tighten up the clearance. Maybe it's the same on our trucks. It's worth a try!
My PW only had one shim behind the hub, and the only replacement we could find in the miscellaneous parts bin is only .001" thinner, but we installed it anyway. I went to the Dodge dealer this morning to drink their free coffee and talk to the parts guy, who used to be an an actual dealer tech. Turns out Dodge had (past tense) an A/C clutch rebuild kit with shims and clips and a few misc parts (PN 5135972AA). It is, of course, discontinued, but he found one at a dealer about 400 miles away, so I ordered it for $24. Turns out to be the same dealer where I bought the PW 13 years ago.

Parts guy said the first thing that usually goes is the A/C fan, which we replaced a couple weeks ago. Next is the A/C clutch, so we are on the right track. Related to the clutch is the magnetic coil in the compressor that engages the clutch, but the clutch rebuild may be able to overcome the weak coil (if that is the issue). Compressor rebuild kit and labor is about the same as a new compressor, so that is a last resort. Looks like the OEM compressor is Hitachi, but there are lots of options if it comes to that. The other likely suspect is the pressure transducer in the refrigerant line on top of the compressor, as previously mentioned by RetiredBLM. Parts guy said the newer trucks use multiple parameters through the ECU to control the A/C compressor, but mine (pre-CanBus) uses only temperature and line pressures, so a simpler system. He also suggested hooking up an old scanner to the OBD port so that I could monitor actual pressures while driving at highway speeds. The old scanners showed pressures, but the new scanners only show code numbers. I don't have an old scanner.

Ducky's Dad
1000_Posts
1000_Posts
Posts: 1489
Joined: Thu May 24, 2012 10:55 pm

Re: Strange A/C Problem

Post by Ducky's Dad » Mon Nov 26, 2018 11:19 am

Finally got a chance to run the PW out to the desert over the weekend, with the new shims in the A/C clutch. Did not solve the problem. Temps were pretty mild this weekend but with the A/C set for max cold and recirc on highest blower speed, a long grade at max throttle got the A/C vent temp to blow 6 degrees warmer than outside air, but still cooler than intake air temp. Basic A/C performance was similar to September when A/C was blowing 103F at the top of a long grade, except that this trip it was blowing 68F when outside air was 62F. Looks like the next step is to change out the pressure transducer.

RustyPW
2000_Posts
2000_Posts
Posts: 4603
Joined: Thu May 24, 2012 4:23 pm
Model Year: 2008
Location: Brownsville Pa.

Re: Strange A/C Problem

Post by RustyPW » Mon Nov 26, 2018 4:22 pm

Mine was acting up like your's some what when I was at the Outer Banks running in the sand on the beach. When I got back home. The dealership sucked down the system and refill it. Said I had about 1 oz left in it. Said the gauges show good pressure before they sucked it down.
PWOC #53
2008 POWER WAGON RC

My build thread. viewtopic.php?f=13&t=2826 :cash: :cash:

Moab '10, '12, '14.
Rausch Creek - Summer '10, Spring-Fall '11, Spring '12, Summer '13, Summer '14, Summer '15, Summer '16, Summer '17, Summer '18, Summer '19 AOAA,

Russ
NRA - Benefactor, Golden Eagle. :lockedandloaded:

Ducky's Dad
1000_Posts
1000_Posts
Posts: 1489
Joined: Thu May 24, 2012 10:55 pm

Re: Strange A/C Problem

Post by Ducky's Dad » Mon Nov 26, 2018 11:13 pm

Thanks. Mine was full in September and the shop even topped off the slight amount that bled off when they tested the pressures. So I'm still befuddled. Just got back late yesterday because we were delayed by the caravan kerfuffle at San Ysidro. We were coming back from Yuma on I-8 towards San Diego and the highway was backed up for about 30-40 miles because highway patrol had closed all the north/south highways in and out of San Diego. While we were sitting there trying to figure out WTF was going on, a couple dozen Border Patrol vehicles blew past us on the center median at Code 3-1/2 toward San Diego. That was our first clue that it would take a while to get home. So today my ass is dragging and I did nothing on the truck.


Ducky's Dad
1000_Posts
1000_Posts
Posts: 1489
Joined: Thu May 24, 2012 10:55 pm

Re: Strange A/C Problem

Post by Ducky's Dad » Wed Aug 07, 2019 8:41 pm

Update is that the PW went into the shop yesterday for its annual physical, and to get it ready for the smog test. It's also getting a new pressure transducer and a new A/C compressor because I'm tired of screwing with it. System will be evacuated and flushed, condenser should be flow tested (could not find an improved condenser), everything will be checked again before it goes to Yuma in a few weeks. Final straw for me was that yesterday afternoon, the A/C was blowing 90F at the dash vents after twenty minutes on the road at freeway speeds. And just to put icing on that cake, my A-pillar grab handle snapped off on Monday afternoon. Ordered a new handle from the dealer and it's just like the old one, no visible improvements and no reinforcement of the mounting bosses, so it's going to break again.

Chubbs
50_Posts
50_Posts
Posts: 50
Joined: Tue Jan 24, 2017 7:34 pm
Model Year: 2018

Re: Strange A/C Problem

Post by Chubbs » Wed Aug 07, 2019 8:58 pm

There are bushings you can buy to strengthen the grab handle. I added those after I went through a couple of replacement handles.
2018 Power Wagon
Bright Silver, Dual Alternators, Leather and Luxury, Ram Boxes

Ducky's Dad
1000_Posts
1000_Posts
Posts: 1489
Joined: Thu May 24, 2012 10:55 pm

Re: Strange A/C Problem

Post by Ducky's Dad » Wed Aug 07, 2019 10:31 pm

The grab handle bushings are available from Geno's Garage, but they don't work on "new production" grab handles, so I didn't order them. I thought ordering a new handle (SRT-10 version with gauge pod for my trans temp) would get me "new production", but when I picked up the part at the dealer it looks just like the old one. So I may order bushings to repair my old handle and keep it as a spare. The color of the new handle is just a tick off from the old one (fading?), so I may go back to the old handle anyway, if I can fix it.

Post Reply