My AC has been running perfectly for the past 3 summer seasons, really cold. Just in a sudden 2 days ago, as the truck sat in the shade and I was doing some texting, hot air start blowing out of vents. It looks like the compressor cycles on and of, during the on cycle (~30 seconds) the air gets cold and the hot again when it cycles off.

I hooked both the high and low pressure test ports to my Harbor Freight gauge set last night. Started the from a cold engine (sitting for at least 5 hours at 90F ambient temp). Before the engine starts, both low and high sides read ~90 PSI. Once I start the engine, low side gradually drops to ~50 and high side keeps climbing up over 400psi and it blows cold air, then it cycles off. From all the readings I did online, I assume that I have a clogged orifice tube. I'm planning to open it up and replace it this coming weekend. Please let me know if you have any suggestions. Thx. Erwin

 

you definitely have a problem in there, high side should not be getting any higher than around 250 lbs of so.
i would disable the ac until oyu can get it looked at before something plows up from over pressuring.

 

Thx. I'll do just that. Erwin

 

The big question is, if the orifice tube is clogged, why is it clogged? Did the compressor toss chunks? If it did, just replacing the orifice tube isn't likely to cure the problem.

 

You have a clogged system. Most probably at the orifice tube. The question is: Why is it clogged? Most often there is a compressor failure which moves particles through the system.

On the bright side, they're easy and cheap (compared to others) to repair. You can find the Compressor, Drier/Accumulator, Orifice tube, and line cleaner for around $300 - $400 as a kit and the 134a for about $60.00 a new Clutch fro $60 - You're set for 10 years!

Go with a smaller Tube if you're in a Hot Climate, one size smaller and makes the air a whole lot cooler on HOT days! I can get down to about 37* at the vent on a 100* day and about 40-45 on a 80* Day.

90*F Ambient Temp should be somewhere in this range:
250-270 PSIG High Side
40-45 PSIG Low Side

 

Thx for the good information on the new part kits. I'm glad that it won't be a leg and arm. Also, the compressor is on top of everything right in front of you instead of hidden under some of my other cars. For now I'll just open it up and look at the oriface if it give me a few more years of service for $3 oriface and $60 r34a then it will be worth it. If not, I'll just have to find the $400 to do the long term fix. Erwin

 

Sounds good. I would also get new O-Rings for the Hoses and use Aerosol A/C Line Cleaner to make sure as much is out as possible if there is dirt in it.

 

Can anybody elaborate on the orifice tube size. I found a couple on Oriellys website. One says for normal climates under 105 degrees and the other says optional for hotter climates with an orifice size of .0605.

Can you tell me what factory size is or what I could go to. My compressor is a little more noisy than it used to be (rattling) so I'd like to find the right one to help with these AZ summers if/when I break into the system.

 

Is there any step by step posts on how to do this. It would be nice to see. My ac goes off every once and a while also. Started last year. I don't have gauges so I can't check pressure.

 

opened up last night. There r lots of relatively "large" chunks of brownish chips (looks like wood chips to me at first) and a few alum shavings. Will do a flush and then charge it and hope to run another couple seasons. Erwin

 

sounds like the compressor is gone.

 

I agree. Probably the early stages of black death.

 

Not so sure,took lots of years to get there could be years of running.

 

when the compressor starts to fail, it usually will not last more than a few months before it locks up.

 

I too would like to know more about the choices in sizes of orifice tubes. I didn't realize there was more than one size.

As these guys said "It's done!" Don't waste your money on freon.
That would be my guess that you would be lucky if it doesn't just lock up in 2 or 3 months.