4230 Air Conditioning Cool but Not Cold

I recently put on a new R134A compressor, flushed the system, installed new filter/dryer, a new evaporator (old one was leaking), and charged the system with 4 12oz cans of 134A. I was talked out of changing the expansion valve. The condenser is clean. The air temperature coming out of the vents in the cab is 70 degrees. It is 95degF here and I'm reading 23PSI on the low side and 265PSI on the high side with the AC on. Based on this information, why isn't my air temperature dropping lower? Is it the expansion valve? Any other suggestions?

1. WHY would anyone talk you out of replacing the TXV????

2. 265 PSI indicates a condenser temp over 150Fº, REALLY high unless it's REALLY hot where you are.

4 twelve oz. cans doesn't sound like enough for a completely empty system but I'm not an ac expert.

If it is really important that this AC works well and works well for a long time, here is my advice:

Take the tractor to someone who specializes in fixing old Sound-Gard cab air conditioners and pay him what he asks. Don't be surprised if you have to drive for a county or two to find the guy. There is more idiocy, fraud, and outright ignorance in the mobile AC field than you can imagine. What works OK in Minnesota or Iowa will last an afternoon where it really gets hot.

You will never, ever become proficient in these repairs by hearsay or message board postings. The information you posted tends to indicate there is too much heat entering the system. The problem is probably compounded by poor condenser efficiency. I also suspect the tests you are running are no where close to the procedure described in the technical manual.

The replacement R134A expansion valve is calibrated a little different than the original R12 valve. But right now, that is the least of your problems.

You can make this AC as reliable as it was when it was it was new. But it is gonna take some $$$ in parts and labor. We don't want to sound like we are beating you over the head. It's just that a lot of us have spent way too much of our lives re-doing these things after they have already been "fixed".

I have converted several systems to 134A and even started using the newer celtec aluminum pump conversion. The new gas should be just as cold. I would change the expansion valve, and while you are up in the top of the cab, clean the evaperator with a coil cleaner. Next, evacuate the system with a good vaccum pump. Pull it down to -25 and let it hammer to get the moisture out of the system. Then turn it off and see that it holds the vaccum, to see the system is leak free. Don't release the vaccum, put oil in if you need it, or hook up your 134a tank and let the vac pull it in. Thats how I was thought to handle a ac system when you break into it. Also, be checking the hi and lo pressures, with the AC on and rpms at pto speed. I have systems that will pump down as low as 15psi on the low side, and be 300 or so on the high side and cool really good. If that same system is at idle, the low side will read 30-40 and high will be much lower. You have to manage the high side pressure to keep from blowing lines, and pto speed checking it will keep you in spec even as the ambient temp increases. Also clean the condenser out front. I promise I am not a clean freak, but I am not going to set in a hot tractor any longer than it takes to get it to our shop and fix it. One other thing, it is better to be comfortable all day than to have goose bumps for a few hours and then the system burst, so don't get wild with the gas.

48 ounces is too much 134A for my JD 4255. It will be after 9AM today before I can ask the technician that changed my AC to 134A but 34 ounces comes to mind. My 4255 cools better on 134a than it ever did on R-12.

I also added extra heater hose cut-offs to be sure "no hot coolant" was flowing through heater core.

Your exactly right about heater hose cut offs. I've got a Maxxum tractor that has a factory installed ball valve close to the engine and if you don't turn it off, it will seep hot water though the cab. it is easier to use that valve than change the valve up in the cab.

My 4240 took 7 cans.The high side pressue could be normal,but the low side is very high.Sounds like the expansion valve to me.Could just be freezing up.

did you vacuum the system ?

I checked with the technician that worked on my 4255 and 36 ounces is correct. If your rec/dryer has a sight glass and you can't see a few bubbles in sight glass the system has too much 134A in it. This is totally different from R12

Question? Did you remove expansion valve when the lines were flushed, if not you didnt flush anything out of the evaporator, expansion valve would have stop anything from going through. 4230 were charged with 4.0lbs of R-12, change over to R-134 charge with 3.6lbs. Anytime I repair a system, expansion valve or orifice tube, reciever/dryer, all lines unhooked then flushed, along with compressor, R-134 oil added back, vacuumed for 30 minutes, let stand for 5 minutes to check for leaks, then shoot the freon to it to high side first then low side, shut both down start tractor and slowly start adding to the low side at no more then 40lbs, till the scales sounds off at 3.6lbs, check for leaks, temp in cab if good, send it down the road. Any question call me tomorrow 815-262-1851. Brent

Most of these methods of dealing with Sound Gard AC's are correct, I do one thing that no one has mentioned, I check for leaks by first pressuring it up to 400psi with compressed nitrogen and then use a soap bottle to look for leaks,,I know this sounds like Hill-billy Tech, but it works "much" better than a leak detector, after I find and repair the leak I charge it up to 400psi again and let it set for 3 or 4 hours,if it holds I vac it out and charge it,,the job will not be succesful if a leak remains.

Thanks for each of the replys. To respond to a few of the questions, I did remove the expansion valve while flusing. Also did pull a vacuum and let it hold to check for leaks. I cleaned the condensor very well. I think I should have replaced the expansion valve while I had everything apart, if nothing else just to remove any doubt. Pressures don't seem to indicate the valve is shot...I'm going to run it for a while, if it gets too warm for me, and if the pressures read similar to now, I'll change out the expansion valve.

Pinch off the heater hoses and see if that helps

my 4230 ex valve had a screen filter in it, the new one from deere did not