I started working on one of my semi's that saw a sudden loss of refrigerant, but without the tell-tale loss of oil. By sudden loss, I mean it within a few days lost its charge but had been charged and working fine.
I 1st saw some oil that might have come from the A/C around the drier (turns out it didn't), and since it was several years old, I went ahead and changed it out as well as a trinary switch that was showing some problems. Wouldn't hold a vacuum, so started investigating further. This is on one of my cabover semi tractors, where the A/C (and heater) hoses connect from the bottom thru the floor into the heater/AC box under the passenger seat. There is a short "extension tube" that goes between the Tx valve and the hose under the cab. It is about 1 1/2" long and has a male insert O ring on one end and a female O ring on the other. It has been a problem in the past and I suspected it now. If I were designing the system I would have used bulkhead fitting in that position. The tube, the Tx and the return (suction) connection are all wrapped in that "tar" dum-dum insulation that was so common year ago. Carefully pealing back the dum-dum I could hear a leak. Using a deep socket I removed the tube to f the fitting at the Tx valve end so corroded that only the "points of the hex nut remained, the rest of the nut was just "gone". I tried putting a new tube on but there was still a leak. Working carefully I remove more and more of the Dum-dum. I seams the junk they spray on the roads, has traveled up the tubes and eaten the Tx valve and even the evaporator connections. The Equalizer tube connection on the outlet of the evaporator was also attacked to the point you can see the threads of the nut, the outside of the fitting it threads into is just gone!
I've seen the junk they spray on the roads in winter attack the silvering between the glass on rear view mirrors, That layer is only a few mircons thick and the junk can get in a eat that out.
What was a simple repair has now turned into a evaporator, Tx valve, new tubes and hose fittings. Evaporators are never a "fun" job and this one is no picnic. I think and hope I have a used one I can replace the damaged one with, even so I have several hundred into the repair already, and a new evaporator is between $400 and $626 if I can get one, non stock item that is on the verge of obsoleteness This truck has a limited number of years running in the winter and with the junk spread on the roads, It has been a back up truck for many years so I really don't know how fast it deteriorates but it is obvious that dum-dum is no match for the chlorides that spread on the roads.
I'll try can get pictures of the damage once the parts are off the truck and in the open. Picture while in situ would be hard to see anything.
I 1st saw some oil that might have come from the A/C around the drier (turns out it didn't), and since it was several years old, I went ahead and changed it out as well as a trinary switch that was showing some problems. Wouldn't hold a vacuum, so started investigating further. This is on one of my cabover semi tractors, where the A/C (and heater) hoses connect from the bottom thru the floor into the heater/AC box under the passenger seat. There is a short "extension tube" that goes between the Tx valve and the hose under the cab. It is about 1 1/2" long and has a male insert O ring on one end and a female O ring on the other. It has been a problem in the past and I suspected it now. If I were designing the system I would have used bulkhead fitting in that position. The tube, the Tx and the return (suction) connection are all wrapped in that "tar" dum-dum insulation that was so common year ago. Carefully pealing back the dum-dum I could hear a leak. Using a deep socket I removed the tube to f the fitting at the Tx valve end so corroded that only the "points of the hex nut remained, the rest of the nut was just "gone". I tried putting a new tube on but there was still a leak. Working carefully I remove more and more of the Dum-dum. I seams the junk they spray on the roads, has traveled up the tubes and eaten the Tx valve and even the evaporator connections. The Equalizer tube connection on the outlet of the evaporator was also attacked to the point you can see the threads of the nut, the outside of the fitting it threads into is just gone!
I've seen the junk they spray on the roads in winter attack the silvering between the glass on rear view mirrors, That layer is only a few mircons thick and the junk can get in a eat that out.
What was a simple repair has now turned into a evaporator, Tx valve, new tubes and hose fittings. Evaporators are never a "fun" job and this one is no picnic. I think and hope I have a used one I can replace the damaged one with, even so I have several hundred into the repair already, and a new evaporator is between $400 and $626 if I can get one, non stock item that is on the verge of obsoleteness This truck has a limited number of years running in the winter and with the junk spread on the roads, It has been a back up truck for many years so I really don't know how fast it deteriorates but it is obvious that dum-dum is no match for the chlorides that spread on the roads.
I'll try can get pictures of the damage once the parts are off the truck and in the open. Picture while in situ would be hard to see anything.
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