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03 f350 xl 7.3 2wd x-tend
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119 Posts
Discussion Starter #1
Ok, my compressor was shot so I got a good one at pick n pull and threw it on. Got 44oz of 134a, because my '93 calls for 2lbs12oz of freon, I slowly put each can in, per directions, both cans feel empty, pressure builds to 45psi when the compressor idles. Once it reaches 45psi compressor kicks on and pulls psi down to 15psi within 1-2 second and then the A/C clutch releases and pressure starts building again. It's currently about 90° outside. Thanks in advance for the help. Every time I get on here y'all have been spot on.
 

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03 f350 xl 7.3 2wd x-tend
Joined
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119 Posts
Discussion Starter #2
Let sit while ate dinner, walked out and hooked up my good gauges and both side have evened out to 100psi. The weather channel app says its 79° right now. Firing it up and seeing what the gauges do. Ok. When compressor engages low drops from 50psi to 30psi and high side goes from 100psi up to 150psi. Anyone have any suggestions? Thanks
 

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Junior Member
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93 Posts
Changing the refrigerant from R12 Freon to 134 requires a compressor oil change. R12 oil is not compatible with R134 refrigerant. The system should be drawn down and leak checked, then recharged. If you do not draw it down, moisture could be trapped inside and turn to ice. I had a situation with debris in the system when I converted my 89 f350 from r12 to r134. near the evaporator on the suction side of the system located inside the line there should be an orifice tube. that is the dividing point between high pressure and low pressure. If the tube is restricted it will cause the high pressure side to be high and the low pressure side will be too low. The tube costs less than $10.00. I had to use a piece of wire coat hanger formed into a small hook to get the tube out, but it is supposed to just be lifted out easily.
 

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Diesel Maniac
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110 Posts
Also I have found a flush of hi side is in order, some parts from compressor may b trapped, then filter suck and recharge. Will need different oil for 134a. Like courtem says
 

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Junior Member
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3,533 Posts
We had to go to a course on the modifications needed to change the system from R12 to R134a, besides giving us a book on which systems in different Class 5 and above trucks needed hard parts upgraded the point they stressed the most was you do not remove the Pag oil from the system that oil is needed for the seals and hoses you add the ester oil to the system they mix just fine, and will carry thru the system as they should.
I am not a believer in adding freon to a system that has been opened you have to evacuate it to make the system work properly.
Just a thought!
 
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