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A/C pressures for a Magnum 7230.


Reichow7120
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Anyone know what the normal operating pressures are on a 7230 Magnum A/C system? R134a system.

Got our new toy today and we knew we have a few things to address. The AC today wasn't working the greatest. Added refrigerant to it and it improved. Just want to know what the pressures should be so I can tell how much or if it needs more refrigerant. 

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presuming the temps were about 85 to 90 there today ? 

A "general" idea on pressures on a hot day should be around 30 low side and under 300 high side if York compressor.  This is a general numbers NOT in stone. 

 I would like to see about 250-275 on high side and 35 or 45 on low side.  A trick that helps get it into the system is to have a bucket of warm water handy and you can dip the can into the water which raises the pressure in the can and forces it into the system. You can use the gauge low side knob to meter in a little at a time and wait and see how the pressures stabilize after a couple minutes. 

I'll push mine to 300 on a smoking hot day out in the sun. You can't do this on a cooler day or you'll overcharge it. Just did that on my 1086. It was 90 out and I ran it to 300. It was cold as all get out but I finally kicked the high pressure cutout after a couple hours in the hay field. I had to back it off a fuzz. My low side never gets much over 35 on any of my 3. 

there are some recent notes from an ac situation discussed here on a 986 with R134a 

hope this  helps

 

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Low 80s and humid as all get out. Sanden compressor.

Thanks for your help. 

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Personally I dont like to see much consistently over 250 psi on the high side.  Compressor life gets drastically reduced from the pressure and heat.  If youre regularly getting over that be sure you dont have too much of a charge or lacking heat exchange across the condenser.  

I cant count how many times ive lowered high side pressures with a thorough cooling package cleaning with the hot pressure washer and a low pressure tip.  Compressed air just doesnt cut it after awhile dislodging dirt packed into the cores.

Some systems have condensers with space to spare, others are barely big enough and just 1/4 airflow restriction causes problems.   

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It depends what your outside temp is , should run between 20 and 30 on the low side and 150 to 250psi on the high side . If you have a reclaimer I think it holds 4.5 lbs or if your just running it in , run the Freon in until the low side pipe stays cold and stop , check your temp in the cab and you should be good . Make sure to check the cab filter , a lot of guys forget to do that . Wash the radiator out and remove the front grill and tip the hyd cooler and the ac condenser power wash it out good , don’t used a rotors nozzle , just a flat fan type tip . 
Danny

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If you have a completely empty system, vacuumed down and ready to recharge the book calls for 4 lbs R134a and 9.5 oz PAG 100 oil for a Sanden compressor. I echo Cdfarabaugh on keeping high side under 250 PSI for compressor longevity. High pressures on a properly charged system can indicate restriction in the condenser fins. A quick way to check for proper charge is to go by the temp as it shows on the gauges. The high and low should average to the ambient temperature. If your system is cycling off and on, go by the highest point just before the compressor kicks off. So if your low side reads 30 degrees and high is 140 degrees on a dual manifold gauge, the outside temperature (or temp of your shop) should be 85 degrees. I was taught this trick by a retired IH tech. It's not 100% foolproof because humidity plays a factor too, but it gets you a close idea where you're at.

A word of caution on using pressure washer on radiators/ condensers/ oil coolers- it works great so long as you wash at 90* angle to the fins. Just don't blast across or they'll bend and you'll be worse off than before! I personally like to use a long blow gun on a air hose (you can buy them from some farm supply stores, I use and sell Radiator Genie here at my shop) and if its really bad wet it down a couple times to loosen all the dirt. Hope this helps.

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What vintage of 7230? Early one that uses a lever for the PTO, or a later one with electric PTO? The AC system changed substantially when the PTO control changed. Early ones used 4 lbs, later ones use 4.5lbs. 

When they went to the newer-style AC system, some bean counter decided it was no longer necessary to install heater shutoff valves on the engine to shut off the water flow to the heater core in the cab....the heater valve in the top of the cab was all that was necessary. We started having problems with AC performance that first summer, due to the heater system having water circulate through it. We installed shutoff valves on a number of tractors, and that fixed the issues with the AC performance. Later on, CaseIH sent out a service bulletin identifying the problem....the person installing the heater control cable and cab heater valve did not adjust the valve/cable relationship properly, causing the hot water to flow to the heater all the time. After we adjusted the cable/valve as described in the service bulletin, the external heater valves were no longer necessary.

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6 hours ago, SDman said:

What vintage of 7230? Early one that uses a lever for the PTO, or a later one with electric PTO? The AC system changed substantially when the PTO control changed. Early ones used 4 lbs, later ones use 4.5lbs. 

Early one with the lever shutoff. 1995 model. 

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wash the livin **** out of the coolers and radiator.  I find using a garden hose with gun sprayer on the end works best.  evacuate the system.  4 lbs of 134a,  replace the drier and expansion valve.  I have found the magnums a/c system requires so little service that alot of the driers are OLD and full and will freeze up because they are restricted..   100 degree day with our humidity I will see 30-45psi on low side and 250 to 300 on high side.  If this fails to give you satisfaction I have an auxiliary condenser here that will drop high side pressure by 50- 60 psi.  My southern guys wont run without them anymore.  Remember the more heat we get rid of the colder its going to get.  Also make sure the tstat switch is cycling the compressor so it don't freeze this is important in the spring and fall.   Never take the tstat switch and cram it all the way around tight.  this seems to not let comp cycle

 

Mike  

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