My a/c has been working ok lately, but I had a 200 mile trip to eastern oregon and the temps were going to be in the 100's and after reading all these a/c problems I wanted to check my system. I hooked up a a/c machine and read pressures. ampient temp was about 90 deg. low side was 60 and high side went to 500!! I quickly shut off truck and evacuated the system the system had 1.8 pounds. I looked under the hood and the sticker states it only takes 1.0 pound. so i charged it to one pound and low side read 9-10 and high side was 190. Those pressures seem pretty low to me. air wasn't very cold. I put another .5 pound. pressures went to 20 and 250. shouldn't low side be about 40? temp out of vents were about 50 deg. now that i think about the first reading I am sure the fan wasn't on. so how much refrigerant do these trucks really hold for a/c to work properly?

 

I dunno, but a shop thats friends of ours put in 4 cans of refrigerant....the coil actually frozed over

 

I don't know the 3rd gens well, but the 2nd gens take around 2 lbs. I would think yours should too. That high discharge pressure makes me think your cooling fan isn't working, or the airflow through the condenser fins is restricted.

 

I am pretty sure my fan wassn't on when i got that high reading. Does your guy's engine fans seem to turn on and off with a/c on very often? Or is mine doing that because of having 1.5 pounds in the system?

 

I just had my '05 2500 serviced for the infamous A/C problems and was informed that I had a leaking condensor which was replaced and that the refrigerant was almost a pound low. The low side was charged to 42 PSI. I'm not sure what the actual refrigerant capacity is but someone on one of the other threads who seemed fairly well informed about A/C issues says that our trucks should hold 1.88 lbs. After the service was completed my interior vent temps while at idle were 42 degrees (drivers side) and 46 degrees (pass side) with an ambient temp of ~88 degrees (the service must have been done in the early morning for that low of an ambient temp).
From all I've been reading here lately it appears that many of our trucks were shipped from the manufacturer with insufficient refrigerant and/or the refrigerant specs tag under the hood is being misinterpreted by some service technicians. My A/C temps are holding so far but I can't say that I'm totally comfortable hoping that it will stay that way for long.
If DC wants my continued business on my next purchase they had better address this issue directly with the integrity we as loyal customers deserve. DC, are you reading this?

 

Look at the sticker under the hood of your truck. One pressure for Gassers and one pressure for Diesels. The diesels are 1 lb. 14oz. or 1.88 lbs. You had the correct charge. With a highside pressure of 500 psi I would suspect a blockage of some type or not enough cooling over the condenser(check fluid dampening of fan clutch). Make sure you vaccumed the system to get out all the air. Also, make sure the condensor is clean and free of bugs. I can't help but think the oriface tube may have crap in it causing the issue. You have to change the line, orifice tube is in the A/C line an is not serviceable.
This may even be the design problem that was changed in the 06' trucks. Orifice tube and fan clutch optimization. I will let everyone know when I check my truck what I find. I have no problem making it blow hot on the drivers side vents. If it was the problem the 03' thru 05' year trucks orifice tube lines may have changed part numbers to the 06' line numbers.

 

I just checked my truck tonight. You can follow along on the 03' AC thread. Yes, pressures are whacked.

 

Stupid question, of course. What type of refrig can I use to fill mine up if it needs it? It is now past warranty issues, 42k for miles. Now being a HOT vermont this year, I think it should be a little cooler in the truck then what it is. I know in the manual it talks about how to check it with temp gauges and I have not done that yet. But is it R134a stuff and could I just purchase a can and throw it in there.

I mean, it does feel a little chilled while coming out the vents, but I'm getting tires of keeping the fan on #3 just to cool the truck down. At #1 or 2 for the fan, it just doesn't do it. I don't know anyone with proper equipment to check this.

 

my pressures were way low with the charge at 1.9. Low side would get sucked down to 10psi and high side 180 psi at 95 deg. There could be something wrong with the fan optimization. The only time pressure looked right was at a 2.7 lb charge.

 

toypar, Please post your issue with the 500 PSI high side pressure on the "03 ac not working on pass side". Beemo "who works for D.C. is trying to help us out. I had the same issue with my truck yesturday.

 

It did it once the first time I hooked the a/c machine up to my truck. The truck was dead cold and the temp put side was 103. I immediatly evac the system and found 1.8 pounds in the system. then I realized the fan was never on and I probably didn't run it long enough for the fan to kick on. I haven't had the issue since then. I have had the a/c machine hooked up a couple times since then. my pressures still read on the low side even though it is over charged by almost a pound.

 

What are your pressures, truck temp, and ambient air temp? My truck did the same thing as yours on the pressure spike.

 

It looks like we have the exact same problem. My low side pressure at 85 degrees outside was 20 low side and 200 high side. If you revved the truck up to 1800 RPMs the low would drop to 15 PSI, not good.

 

Thats exactly what mine does when i rev it up. That is why I charged it higher than the factory 1.88 to get my pressures right. it blows 41 deg out of both vents now in 95 deg weather. I don't know if the pressure spike was a one time only occurance or happens often in my truck. I will have to hook up the machine this weekend and give you some pressure readings, I can't remember off hand what they were. I know they were low.

 

Toypar,
Please post your reading with the cooling fan running and not running.

MikeyB