Ok history, Got truck beginning of june a/c worked decent. All of a sudden one day blowing hot. Stuck gauges on in idled up very low on freon. Recharged last two weeks out of freon again. Recharged sunday, few days after not working very good. Low again. This time I recharged and used a sniff detector went over whole system could not pick up any leaks. Stuck the leak detector in the air vents and drain tube and got no hits anywhere. Do these have some sort of pressure relief valve that may be dumping the freon? I have never heard of anything like that but thats really the only thing I can think of. I am at a lose on this one.

And no I dont want to run stop leak in it, I would much rather find problem and fix it.

UV dye, black light. They do have a high pressure vent off valve. Not sure if it's one-time or closes after pressure drops.

UV dye, black light. They do have a high pressure vent off valve. Not sure if it's one-time or closes after pressure drops.


Was told by previous owner a shop supposedly recharged and added dye but could not find leak. I do have the glasses and UV light so I may go over it and see what I can find. Guess if I dont see anything then it must be in evap. I also do get the infamous passenger side vents warmer than driver side so I guess I need to change the blend door anyways. I checked the recirculation door just now and it is good. With adding the dye is there any change of it stopping the system up? I do appliance repair for a living and I do refrigeration and we install driers that have UV dye already in them.

My experience with the different temps between driver and passenger side goes away if I have the a/c off when starting the truck and then turning it on after I start moving. Basically you need air flowing across the condenser to prevent a spike in pressure which must cause an incomplete frost pattern on the evap until it equals out.

My experience with the different temps between driver and passenger side goes away if I have the a/c off when starting the truck and then turning it on after I start moving. Basically you need air flowing across the condenser to prevent a spike in pressure which must cause an incomplete frost pattern on the evap until it equals out.

Makes sense. I am wanting to get the freon issue fixed before i try to figure out the different temp thing. The previous owner did take it to a dealer when he had the work done. You know how long that dye last? Its been a few months at least since he did that. I wonder if I would still be able to see it.

Makes sense. I am wanting to get the freon issue fixed before i try to figure out the different temp thing. The previous owner did take it to a dealer when he had the work done. You know how long that dye last? Its been a few months at least since he did that. I wonder if I would still be able to see it.


Why try to figure it out. Lots of stuff on here, just search. It does sound like your evap is done. With that big a leak, it should fail the vaccum test.

Oh I searched and searched for a couple hours last night. Guess I'll pick up a evap and blend door just in case. I'll pull a vacuum tonight and see what it does.

Here is one.

http://www.dieseltruckresource.com/dev/04-5-c-passenger-vents-not-cold-t245620.html

The original thread. Have fun reading.


http://www.dieseltruckresource.com/dev/03-ac-not-working-pass-side-t106452.html?&highlight=passenger+vents

Wow thanks. Just the start of the one answered one question that you can lose freon and not have a leak... Even the dealership agreed if I am losing freon there has to be a leak.

The reasons are in the threads. At the right time, the high side will spike up to 450 psi due to lack of air flow over the condenser. It'll make a leak....LOL It normally takes about a year to get low on freon. Sometimes the high side can spike high enough to activate the pressure relief valve on the back of the compressor. You'll see a big fog cloud and it happens on first startup in very hot weather when the truck is cold. Keep reading, lots of good info for ya. Evac the system and draw a vaccum on it. Let it sit for 30 min. if the vaccum drops more than 1 psi, you have a leak.

Consider a new heater core if you have to go deep enough to do an evap core. You'll know what I mean once you get in there. You won't want to go back and ALWAY replace the dryer if you open the system. Also add 1 ounce of the correct and NEW UNOPENED oil for every component you replace besides the compressed. (there's a different way to gauge how much oil to add when changing that)

If it's had the ac worked on before, look under the hood for a UV Dye label. Shops usually stick one somewhere if they've added UV Dye before and they usually put some in when they have to look for a leak, which is usually why it gets worked on in the first place. Might save a little $$