ISO solution to recharging AC often due to Ram's ECM defect opening the AC relief

[Bob4x4]

I stand corrected about extreme heat being a factor at all. If I idle the truck cold on 75 degree days like we have now I can still get 450 PSI on the high side. Further watching the fan % commanded to 99% at idle the fan is doing a lot of NOTHING for a LONG time. The only thing that matters is the fan isn't kicking in from around 250PSI to 450+ PSI. Specifically seeing less than 400 RPM on the fan.

Do you have the latest flash?

 

[Bob4x4]

I stand corrected about extreme heat being a factor at all. If I idle the truck cold on 75 degree days like we have now I can still get 450 PSI on the high side. Further watching the fan % commanded to 99% at idle the fan is doing a lot of NOTHING for a LONG time. The only thing that matters is the fan isn't kicking in from around 250PSI to 450+ PSI. Specifically seeing less than 400 RPM on the fan.

Do you have the latest flash?

 

[scootergmc]

So I have this same problem- starting two years ago, refilled last spring, blows warm again. No leaks detected/located, nothing, and it rarely gets driven. If this is my problem, what a pain, maybe I'll just sell it- that or just top it off every year?

 

[Tuesdak]

So final answer is the electronically controlled fan does not lock up fast enough or at all from a cold start at idle speed. Outdoor temp has nothing to do with the eventuality that the system will 'run away' and vent from overheating the condenser. Blower speed doesn't matter because low speed won't buy enough time - again because the fan isn't locking up at all. The official fan clutch test is to short a wire and wait 15 min for the fan to kick in. It doesn't take 15 min to vent the system at 450+ Psig even on low speed.

Solution is high idle with blower on low till the fan kicks in.*

*Without gauges you can hear the fan kick in. Once it's locked in you are ok to use normal idle RPM and higher blower speeds. I don't use high blower speed when idling unless I am watching the guages. This is lower risk then the OEM vent the system at idle setup. If you have high idle it's best to leave it on anyway. Gauges would take the guess work out of this. My Smarty is set to alarm at 400 Psig for AC high side pressure.

Watching my Smarty Touch I see 99% commanded fan from AC pressure at idle cold start. Going from 250 to 450 Psig the ~500 fan RPM doesn't change at idle. Now if I take the same cold start and bring the engine speed up to 1200 RPM (high idle if you will, no I don't have high idle working on my 2003) the fan's 500 RPM will lock up before 400 Psig. Warm engine idle the fan kicks in from low RPM.

No, being in Phoenix is actually an advantage: the cool days (aka my winter your summer) when the fan can kick out and stay out leads to more cold starts with the fan kicked out. Hot days has the fan lock in before I shut it down and it's locked up in morning sickness the next cold start avoiding the problem. Yes, the AC system is cooled by Ram Air so if you get moving the fan doesn't have to kick in unless it's hot out with blower on high and that's still MPH dependent.

So there you have it: two problems collide to vent the AC system.
1) No ECM high pressure kick out of the AC clutch before the system safety valve vents.
2) Unlocked cold fan clutch will not lock up at idle RPM.

As an aside IMO this is why the "electric fan" solution doesn't work 100% - the electric fan isn't delivering enough cooling alone. Idled long enough the clutch fan isn't kicking in and eventually the AC pressure rises and vents.

Do you have the latest flash?

Checked with dealer and there are no flash updates for my 2003.

 

[BILTIT]

So basically, I should stop using my remote start and idle up anytime I cold start. I will be filling my AC shortly again.

 

[Tuesdak]

Wow! Ran across the specs from Sanden, the OEM supplier of our compressors. More or less should not be going over 430 psig ever and max of 400 psig. I did find that Dodge has improved the condenser design to the more efficient design so I ordered one and had a Thermal Dispersant coating applied to it. Mainly because my Idle pressures are so high in Phoenix. I will also follow the oil level procedure they provide on page 11 to make sure excess oil isn't a problem.

6.6.1 Discharge gas conditions

Short term peak: 430 psig max. (short idle or short acceleration time)

Limited term: 400 psig max. (extended idle or short acceleration time)

Long term continuous: less than 300 psig. Up to 4000 rpm (for optimum life)

Max continuous temperature: 280 deg. F (300 F short term)

http://www.sanden.com/productlibrary/manuals/SD_Service_Guide_Rev_2.pdf


Current Condenser:

New Coated condenser:

 

[Dan_69GTX]

How much did the new condenser help?

Re the thermal coating - have you used this before or is this the first time? Thoughts on it?

You show to be from Phoenix. We lived in Glendale from 87-92. My brother and some of my wife's relatives still live out there. Nice place but I don't miss the heat or the traffic. Low humidity was nice!

 

[Tuesdak]

Time for an update. This past spring I was watching the AC high side just run away no matter what. The 400 Psig event in a drive through line after engine warm up was showing me that the fan clutch was taking forever to respond and get up to speed. Considering the fan clutch was at least 6 years old IMO it's due anyway. (It's a known 5 year fan clutch life on obsolete spring thermal fan clutches as they loose 200 RPM per year. Guess this is one way electronically controlled viscus clutches slowly die.)

So I replaced the fan clutch with a MOPAR unit from Geno's Garage. (Their advice was the fan should be on in about a block with the AC on. Yeah, it used to do that when I bought the truck.) I also replaced the fan shroud because the old one was hard and had some of the lower shroud retainer parts were missing having broken some unknown time in the past. The old shroud was so stiff it came out with a sawzall. The new one had enough flex to install without major surgery. The coolant recovery bottle was in the way as I recall.

Replacing the fan clutch on a 2003 with common household tools:
1 and 7/16" wrench, 8mm wrench, BFH, and large screwdriver/prybar. Removed two 8mm bolts so the 1 7/16 would clear. Good wack or three and it comes loose.

Holding two bolts with the screwdriver on the pulley.

Dealer had a difficult time finding the part number for the shroud on my 2003.
New big part is: 52028912AF
The small bottom part is: 52029081AD

The 6.7 damper I put on makes this job a little tighter taking the fan out the bottom.

There was some confusion from my shop in the past if I had a MOPAR or aftermarket fan clutch. The Prior Owner said he had replaced it. Looking at the new MOPAR fan clutch and the one that came off the truck was only once difference: The new fan clutch had a MOPAR part number on it.

How much did the new condenser help?

Re the thermal coating - have you used this before or is this the first time? Thoughts on it?

You show to be from Phoenix. We lived in Glendale from 87-92. My brother and some of my wife's relatives still live out there. Nice place but I don't miss the heat or the traffic. Low humidity was nice!

Results of the Thermal Dispersant coating on a new condenser are here.
https://www.turbodieselregister.com...thermal-dispersant-on-an-ac-condenser.264486/

Combined with a new fan clutch the head pressures are down in town.

 

[Prairie Dog]

Truly not trying to be a smart-ars, just trying to understand - but why have I not had a problem with this on my 15 y/o, 108K mile truck?
Although I do admit that this year, for the first time ever, I've had my evaporator freeze up twice but hasn't done it in a month.

I didn't either. That was until last year when I finally had the same low freon issue. Probably took a long time because AC just doesn't get much of a workout here. Mine started screwing up by randomely freezing just like yours.

 

[nibroc]

interesting read-------thanks

 

[Prairie Dog]

I could update my last post too.
I finally got so low on freon that the compressor wouldn't kick on. I had to put a bunch in and it works fine again. Also, I just ordered a new clutch fan. Heck, the old one doesn't even have "morning sickness" anymore.
This whole thread has been super helpful and I've learned how to keep mine from venting. Thanks to all who contributed.

Hey Tuesdak, any chance you could give us the new Condensors P/N?

Thanks!
Scott