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03 f350 xl 7.3 2wd x-tend
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119 Posts
Discussion Starter #1
Ok, been awhile, but I have a '93 N/A and the A/C won't work. The fan blows good, the compressor kicks on, no unusual sounds from the compressor but its not cooling the air. I checked the the pressure on the low side and its good. Also just recently started smelling antifreeze when the fan is on and get a little "fog" on the windshield but haven't seen any coolant on the floorboard or noticed the level go down any? Any help will be appreciated, thanks.
 

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Junior Member
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93 Posts
A/C problems
in order to smell coolant in the cab I think you have a small leak in the heater core. It is located behind the glove box. If the AC compressor is operating and no cool air entering the cab, check the vacuum lines to the mixing door. there may be a small vacuum accumulator, probably on r/fender, look for a disconnect vacuum line. Also check the heater hoses at the firewall for water leak near the connection to the heater core. it could be letting in a small amount of coolant into the heater compartment causing the smell.
 

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Formerly Powerstrokin350
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9 Posts
Yes, I forgot my password for my powerstrokin350 so I'm N/AF-350 now, but I replaced my heater core. As parts guy told me unlike Chevys these fords have a drain that dumps a heater core leak on the ground and not your floor board, and my a/c problem was I replaced the compressor with one from a junk yard and flushed the system and replaced my orifice tube. Works awesome. Blew colder the monkey snot for the last few hot days, but of corse now it's getting cooler and don't need the ac but to dry the defrost. Since winters coming its time to fix the glow plugs.
 

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Formerly Powerstrokin350
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9 Posts
glad it worked out for you. was the orifice tube dirty?
Yes and clogged up with the old compressor shavings, that's what was causing all the problems. I just couldn't think that was my problem because when I pulled the compressor and looked at the lines there were shavings in the hose at the compressor but no where else. I disconnected the hose at the other side and blew it out and nothing came out. So it had collected at the compressor and the orifice.
 

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Junior Member
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93 Posts
The A/C system is pretty much a free flowing closed system. If the orifice tube were not in place the entire system would be about the same pressure just moving the refrigerant around. I has to compress the gas to a liquid form in order to work. It works on the same principles as the engine cooling system. Under pressure the liquid will not boil at its normal boiling point at sea level. R12 (freon) boils at about -72C. In the low pressure side the refrigerant enters the evaporator core and boils as it absorbs heat from the airflow over the core. It then goes to the compressor as a gas (can not compress liquid) and turns back into liquid form and gives off it's heat in the condensor core. That is why when you check the exhaust of an airconditioner it is usually warmer than the surrounding ambient temp. The orifice tube in the system is a choke point for this action to occur. The restriction that is created at the orifice is the valve that allows for the compression of the gas to a liquid.
Any small particles that can be trapped anywhere are like to be found at the orifice tube screen.

In my system I had a rapid decompression. I replaced a hose and tried to service the system. It did what your's did. High pressure got very high with almost no low pressure. When the line ruptured the desicant in the dryer/accumulator ruptured and sent debris into the gas flow. It all got choked out at the orifice tube and pluged the passage between low and high pressure. Glad you got it straightened out.
 
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