dbrannon79
I'm getting there!
Hey fellas, I had some thoughts cross my mind on modern AC systems vs the older systems vs the really older systems and how well their performance is.
I had the crazy thought of what if I tried to convert the system on my rig over to use an expansion valve or TXT valve and get away from the fixed orifice tube design.
I doodled around on the innerwebs looking for conversion kits and only came up with kits that converted the older TXT units to a fixed orifice, nothing the other way around.
as much as I have toyed with the AC systems in various cars and trucks over the years, I have always found that an expansion valve equipped system cooled the best as far as having that crisp fridgid air flowing from the vents that's barely above freezing temps. all of the modern and foreign vehicles seem to have well designed systems with the exception of the "known to fail" compressors. even the older ones that used the TXT valves that got converted over to 134a cooled really well. now we take both GM and Ford with the fixed orifice tubes and it was always a hit and miss when it came to getting this kind of performance out of the AC. I know dodge uses an orifice too for what ever reason dodge seemed to know what they were doing and made it work!
I am already planning to convert mine to use a sanden compressor at some point, I am currently on the look out for a junk one to use as a mock up for mounting and clearance issues soon, but I was thinking what if I could eliminate the orifice in the condenser (remove and put the lines together without) and down the line closer to the evap fit an expansion valve or TXT with the cap tube. All of the big rigs we work on at my work, Freightliner, Kenworth, Mac, Volvo, they all use an expansion valve or a TXT combined with a sanden compressor. the sleeper AC is an option in some of them but they all will freeze you out of the cab. Now I realize the condensers are considerably much larger than what's on our GMT400's but take the average Caddy or newer burb or truck where you almost can't have the vents directly blowing on your hands while driving else your knuckles start to lock up from frost bite! sticking a thermometer in those vents and you get somewhere in the neighborhood of the high 30's to low 40's temps. our GMT400's or at least mine will only get down to the 50's if the outside temp is in the low 90's or lower. any hotter outside and the vent temps go up from there.
Honestly I think the simplest would be to use a TXT style valve that only uses the high side line, having hoses made so it goes from the condenser to the valve and then a short hose to the evap, with the cap tube ran into the cab on lower evap connection onto the evap fins. Though I would have to do some research on getting the right sizing on the TXT.
now this idea might only work for a front only system and not so much for one with a rear unit, but then again the newer burb's use a dual expansion valve system.
I just thought I'd post this out there to get some thoughts and feedback on this since I'm planning on replacing the compressor with the sanden unit along with using the more modern condenser once my AC
's the bed. My current R4 compressor has been trying to lock up on me lately when I first turn it on, once it overcomes whatever is happening it with work the rest of the day. When you first turn it if the engine is only idling, the belt will chirp and squeal, if turn it on when the RPM is up over 1k it will squawk a little and then start working. I have also noticed it's putting a heavier load on the engine too it seems like. I verified it's the compressor while one morning trying to rotate the clutch by hand, it was extremely tight! So I know it's ready to go any day now.
I had the crazy thought of what if I tried to convert the system on my rig over to use an expansion valve or TXT valve and get away from the fixed orifice tube design.
I doodled around on the innerwebs looking for conversion kits and only came up with kits that converted the older TXT units to a fixed orifice, nothing the other way around.
as much as I have toyed with the AC systems in various cars and trucks over the years, I have always found that an expansion valve equipped system cooled the best as far as having that crisp fridgid air flowing from the vents that's barely above freezing temps. all of the modern and foreign vehicles seem to have well designed systems with the exception of the "known to fail" compressors. even the older ones that used the TXT valves that got converted over to 134a cooled really well. now we take both GM and Ford with the fixed orifice tubes and it was always a hit and miss when it came to getting this kind of performance out of the AC. I know dodge uses an orifice too for what ever reason dodge seemed to know what they were doing and made it work!
I am already planning to convert mine to use a sanden compressor at some point, I am currently on the look out for a junk one to use as a mock up for mounting and clearance issues soon, but I was thinking what if I could eliminate the orifice in the condenser (remove and put the lines together without) and down the line closer to the evap fit an expansion valve or TXT with the cap tube. All of the big rigs we work on at my work, Freightliner, Kenworth, Mac, Volvo, they all use an expansion valve or a TXT combined with a sanden compressor. the sleeper AC is an option in some of them but they all will freeze you out of the cab. Now I realize the condensers are considerably much larger than what's on our GMT400's but take the average Caddy or newer burb or truck where you almost can't have the vents directly blowing on your hands while driving else your knuckles start to lock up from frost bite! sticking a thermometer in those vents and you get somewhere in the neighborhood of the high 30's to low 40's temps. our GMT400's or at least mine will only get down to the 50's if the outside temp is in the low 90's or lower. any hotter outside and the vent temps go up from there.
Honestly I think the simplest would be to use a TXT style valve that only uses the high side line, having hoses made so it goes from the condenser to the valve and then a short hose to the evap, with the cap tube ran into the cab on lower evap connection onto the evap fins. Though I would have to do some research on getting the right sizing on the TXT.
now this idea might only work for a front only system and not so much for one with a rear unit, but then again the newer burb's use a dual expansion valve system.
I just thought I'd post this out there to get some thoughts and feedback on this since I'm planning on replacing the compressor with the sanden unit along with using the more modern condenser once my AC
's the bed. My current R4 compressor has been trying to lock up on me lately when I first turn it on, once it overcomes whatever is happening it with work the rest of the day. When you first turn it if the engine is only idling, the belt will chirp and squeal, if turn it on when the RPM is up over 1k it will squawk a little and then start working. I have also noticed it's putting a heavier load on the engine too it seems like. I verified it's the compressor while one morning trying to rotate the clutch by hand, it was extremely tight! So I know it's ready to go any day now.
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