I've been having problems with the A/C ever since I bought the truck. Thought I had a leak somewhere, so I put the dye in it and could not find anything. I took it to mechanic (local) and he went over the system with his Snap-On sniffer and could find no leaks. But he did say:

The fan clutch is not working, so there is not enough airflow through the condensor and the condensor is getting way too hot, causing extremely high pressure buildup, which is causing the safety valve on the compressor to open. This is how I'm losing freon.

Does this sound right? I thought that there was a (too) high pressure sensor that would prevent over-pressurization. He said he saw it spike up to almost 500 psi!!

Also, should the fan clutch be fully engaged whenever the A/C is on, regardless of engine temp?

03 2500 SLT, stock, 5 speed, quad cab, longbed

 

That makes sense. I don't know what you have but my 03 fanclutch has wires going to it and it drives harder when the ac is on. Craig

 

The fan clutch is controled by the ECM. This is exactly why we have so many issues with the A/C systems on these trucks. I did a retrofit to my truck courtesy of BEMO. It has worked for 2 years with no issues. My truck has now leaked down again. My opinion the programming is not quite right causing the high spike. You will mainly see it with a cold engine. If you get going down the road before you turn the A/C on the spike is not as bad and you will not loose freon. Make sure you only have 2.00lbs of refrig. in the system, don't overcharge it with freon or oil. My next step this year is to put a electric fan on the front of the condenser (slim line 2" thick) with a thermostate control and A/C on control. This should stop the high pressure spike with a cold truck and in stop/go traffic when the fan dosen't come on. Their is no real fix for this. Guess I am going to have to make my own.

 

So the spike is indeed caused by the condenser getting too hot? If so, then it seems that the best fix would be an electric fan with controls as you described. That should prevent the overheat.

 

If you do any towing you will want to get the fan fixed electrics can't move enough air to keep it cool

 

I've hauled a small trailer (1 ton), fairly regular, with my bed full of materials too, and I've never had the temp needle go much past 200, even on hot days. After digging thru the forums, I suspect the fan clutch is working OK. I wouldn't really know for sure unless I hooked up a scan tool that could turn the fan on manually.

My current plan is to only use the A/C once I get up and going, and turn it off in traffic, just to see how long the charge lasts. If I lose charge again then I'll have someone do an evacuation, check the amount of oil, then recharge. Sounds like I might need to install an electric fan as well....

Spooler, can you give more info on the BEMO retrofit?

 

Mine seems to work fine, even in the desert and city driving. Is there a reflash to make the fanclutch work better in A/C? Or maybe add a temp switch to the A/C compressor discharge line to bring on the fan when the A/C is on and the discharge gets hot enough? Craig

 

I will reply back to the questions later.... Kinda busy at the moment.

 

This is just an added electric fan on the condensor, the factory is still used. No towing worries.

 

Do a search for "03 A/C not blowing cold on the passenger side" lots of info. The fix is a new orifice tube line and 2.00lbs of R134a. All the part numbers are in the thread.