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Originally Posted by vegasruv24.1
first off... I am willing to throw everything I know, or think I know out the window to learn something new....the probe deal...seems to me that it is a temp sensor that senses 32 degrees and shuts the compressor down..... sound about right???? and the AC is a cold / heat exchanger.... right... meaning the Freon comes in to the evap cold, the warm air inside blows across the evap and cools and blows out the service duct... the hot Freon goes then to the condenser...where it is cooled... then back to get re compressed, making it cold again... sound about right???? so the probe does nothing till the evap gets to 32 degrees.... right???so would you mind giving more imput that I obviously don't have....how would moving the probe up or down do any thing, unless you were freezing up the coils???next,... the very most efficient...is a 22 degree split.... your say'n that you are getting a 27 degree split... but @ 90 degree ambient temp, 72 is only a 18 degree temp drop...
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Vegasruv24.1- I got your PM but was preoccupied today.
I like what you first said here, being willing to throw out something you thought you knew to learn something else is the sign of a smart person. I know I've had a whole pile of things I THOUGHT were one way, only to learn they were another. It pays to have an open mind, that's for sure.
So the biggest thing I can say is I THINK the thermistor isn't letting it get anywhere near 32 degrees. That's the key here. This is what I mentioned earlier here...
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It seems to me that Coleman is pretty conservative on their evaporator icing prevention strategies. I think they're cycling the compressor at temps that are way too high.
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What if they were cycling back the compressor at temps that are way higher than 32 degrees? H#ll, I don't even know if these compressors are variable displacement, expansion valve or orifice tube systems. I never got that far into bothering to find out more about the compressors themselves. Anyway they do it, they clearly have evaporator icing feedback because they have a thermistor. So they can be as aggressive or as conservative as they want with those strategies. What I did by removing the thermistor from the evap core was basically being as aggressive as you can be on the compromise between low output temps and chance of icing.
I do know this... Coleman has to be SUPER conservative on their units because the same design/calibrations have to work "OK" on hundreds of different applications. It's very similar to what I said in the 5 Star tuning thread, the way Ford has to be VERY conservative on how they calibrate the engine operation on an engine that has to be used in hundreds of different situations and conditions.
This is important because it means there's the strong possibility of major improvements in efficiency in your (ours, or anyone else's) particular situation. If Coleman makes an RV roof air that they absolutely don't want to ice up because it would result in bad customer experiences, they have to make sure it won't ice up in the worst possible situations. I personally want the compromise to be maximum cooling and would simply avoid the "worst possible situations". Like closing all the vents or leaving the AC run all night, or running it non-stop when it's not that hot out.
BTW where did you come up with a "22 degree split" being the "very most efficient"? Just curious. I've had aftermarket dash AC's in cars and motorhomes that would turn the evap core into a giant ice cube in 100+ degree weather. Easily putting out 30 or even 40 degree temp drops from inlet to outlet.
If I get bored, I'll get you guys some actual real data. I can monitor the AC amp draw in my Vegas. All I have to do is put the thermistor in a glass of water and see at what temp the compressor cycles or changes displacement. I'd start with ice water, moving up the temp to find out EXACTLY how cold they let the evaporator core get. Or you guys can just be crazy and try what I suggested. Just pull the thermistor out of the evap core and see what happens. Sometimes you just have to throw theory and debate out and experiment blindly.
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