AC problem probably fixed, advice needed.

[scootergmc]

So my AC has been slowly leaking over the past few years and I've refilled it a couple times only to have it happen again. Trouble is, we don't drive it much so I usually ignore it until springs rolls around. This year, I figured I'd try to figure it out. My buddy pulled a vacuum and refilled the refrigerant and dye. The truck wasn't overheating (190-200) and I had no fan clutch code (no soft code either), but after we filled it up this time and noticed the high side pressure was way high, so we pulled some of the refrigerant back out and we figured the fan wasn't doing its part. We checked for leaks all over and found none, including the evaporator. Started driving so I could replicate the problem and a couple days later I checked for dye with a UV light at night and the only place it appears is like a fine mist dried on the right side of the engine above and behind the AC compressor.

In the meantime I bought/installed a new OEM fan clutch on a couple days later and now it's locking the fan at low RPM (I forgot how loud it was first thing after cold start) and the AC is still working a week later. So I figure that prior to the fan replacement it was blowing it out the relief on the compressor due to over pressurization. I'm ready to top it off with refrigerant now. Do I need to add oil for the compressor? Should I vacuum the system again and start with a fresh refill? Thanks.

 

[xcc_rider]

Only way to get the proper fill is to vacuum again and fill with the recommended volume.

I would think you're good on the oil.

 

[scootergmc]

I too would think I'm good on oil.

 

[Tuesdak]

the only place it appears is like a fine mist dried on the right side of the engine above and behind the AC compressor

It's not leaking. It's (refrigerant and oil) being blown out the relief valve at 450+ psig as the spray pattern you described... The run away high side pressure is also normal on these year trucks because the cooling fan isn't up to speed. It's complicated and more than just the fan. (High side pressure running away is a quick verify with an IR temp gun on the hot condenser and now you are dealing with a cooling FAN problem causing the AC symptoms.)

I would replace the fan clutch if it's over 5 years old with a new MOPAR fan clutch. They loose 200 RPM per year that the ECM compensates for and also spin slower when kicked out as they age. Eventually they can't lock in fast enough and the AC system overheats. When it overheats the high side pressure goes over 450 psig and the relief opens on the back of the compressor dumping out 1/2 the system charge. The dye paints the oil filter and everything behind the compressor.

Even then that's not a 100% cure as these trucks did this even when new. Some have had luck with a electric fan strapped to the condenser. I suggest speed 2 or lower on the blower till you hear the engine fan come up to speed.

Oh yeah a little bug where the ECM doesn't kick out the AC compressor on extreme high side pressure that the engineers never figured out in the day. These systems will relibily vent the refrigerant under some specific conditions.

Long story:

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

 

[scootergmc]

Thanks Tuesdak-

I did replace the fan clutch, not the fan, and I found that issue by reading one of your old threads. Definitely was the issue as far as I can tell.

 

[Tuesdak]

I would still start the engine using no more than blower speed of 2 until you hear the engine fan pulling air. That rare time the fan clutch doesn't have morning sickness may vent the system if you run higher blower speeds.

 

[scootergmc]

10-4. Should I just vacuum again and do the recommended fill on the tag? Thanks.

 

[Tuesdak]

10-4. Should I just vacuum again and do the recommended fill on the tag? Thanks.

Yes.

 

[scootergmc]

Just to follow up, it seems to be working great. The only other problem I have is that all my HVAC doors move slowly. I have removed the motors and tested them and they seem to have a mind of their own. If I move the knob, they sometimes move, sometimes not, and if they move it's slowly. I replaced the controls but there was no change. Does the HVAC have a reset procedure?

 

[scootergmc]

OK, so it seems like my problem is back. The passenger side vents have gone warm again so I know I'm losing refrigerant. The truck doesn't have morning sickness (it did when I replaced the fan clutch), but maybe that's due to ambient air temp?? The engine temp rises over 200 (probably 210ish) before beginning to cool and unless I'm on the freeway it doesn't happen quickly. In town transmission temps can hover anywhere from 160-180 depending on ambient temperatures (can be 100+ here). I don't know where to start. I've read about corroded connectors, wiring, TIPM issues, etc.

 

[brucejohnson]

I had a similar "slow leak" situation in my former '02 for a few years in a row. Many parts were changed over that time. Long story short, It ended up being a very slow leak in the compressor.

 

[Tuesdak]

OK, so it seems like my problem is back. The passenger side vents have gone warm again

The problem is always "there". It's a defect where the ECM will not kick out the compressor clutch when the high side is overheating for any reason. The trucks did this brand new. Some strapped an electric fan on the condenser and even that's not a 100% cure. I replaced the evaporator on mine and at the end of the day there were no leaks. I even replaced the pressure sensor on the high side of the AC system.

As always leak check your system. It's always possible you have a leak.

However if you see that the relief valve blew out because it dye painted the oil filter: that's the problem. Evac and recharge the system and call it a day.

With the A/C on does the fan start roaring in about 1 block of slow driving?

 

[scootergmc]

We did a refill/leak check before I replaced the fan clutch and the entire right side of the engine was yellow and the oil filter coated. That's how I diagnosed the fan clutch. There was nothing visible or detectable. The only loss was out the relief prior to the fan clutch replacement. I never had this problem until about 5 years ago and the truck has sat a lot in those 5 years. So I guess there is a chance a compressor seal could be bad causing a very slow unnoticeable leak, or the relief itself is bad. But would that keep the fan from morning sickness?

No, with the AC on the fan does not start roaring. Tried it yesterday just to make sure. Ambient air temp was 88 degrees. I will try it again today when I leave work.

 

[scootergmc]

I should add, the truck is still a cream puff. It's had a great life, only 125k miles, no wiring chops, added goodies, Smarty Jr. has only ever been on fuel economy, etc.

 

[Tuesdak]

Fan may need a once over. Wires come loose amd go through the fan? MOPAR fan clutch or aftermarket?

 

[scootergmc]

Wiring is good. The replacement fan clutch is Mopar OEM- Vistronic if I'm not mistaken?

 

[Tuesdak]

I missed that maybe the system hasn't been recharged yet? There may not be enough R134a left in the system to raise the high side pressure enough to kick the fan on.

Again verify the relief is the cause by checking the oil filter for being misted with A/C oil - I assume you wiped it off or changed the oil since the last trouble? The safety relief valve itself isn't the problem unless it's leaking.

Evac and recharge the system then make sure the fan kicks on in a block or two at 25 MPH with the A/C on high.

 

[scootergmc]

Yes, the system was evac'd and recharged to the proper spec after the fan clutch replacement.

Yes, the oil has been changed since all this was done, and the new filter has no A/C oil coating it.

When I left work tonight (a few hours ago) I turned on the AC and drove slowly away- no morning sickness at all.

When I just went out to check for AC oil on the filter I tried turning the fan by hand, it had resistance but it did turn. I don't know if this is normal. The fan wiring also looked good.

 

[scootergmc]

I had a similar "slow leak" situation in my former '02 for a few years in a row. Many parts were changed over that time. Long story short, It ended up being a very slow leak in the compressor.

I suppose it could be a very slow compressor leak, unable to be detected, but I don't know how that would affect the fan behavior. I could very well be dealing with compound issues given its age.

 

[brucejohnson]

I suppose it could be a very slow compressor leak, unable to be detected, but I don't know how that would affect the fan behavior. I could very well be dealing with compound issues given its age.

I believe Tuesdak addressed the fan issue stating the system detects a low charge which may cause your inop fan symptoms. I know your system is more involved than the Gen 2's, but the basic symptoms and protections are still valid between the systems. Yours has more controller events to play with operations stuff. Multiple issues can arise anytime "Murphy" gets involved.