Live evap but no air blowing, parallel evaps in coach HVAC

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Al9
Posts: 14
Joined: Tue Mar 10, 2020 3:26 am

Live evap but no air blowing, parallel evaps in coach HVAC

Postby Al9 » Wed Mar 11, 2020 7:07 am

Hi everyone.

OT (as in Off Topic) since this really isn't automotive AC.

Lately, i've been reading a lot about automotive single compressor parallel evaporator systems.

I understand that, in cars, provided you sized the compressor right and the plumbing has been done right (so that the oil won't get caught anywhere even with low refrigerant velocities, even though it may pool in the evaporator), you won't even need solenoids or TXVs that won't close all the way (either due to a well placed nick or due to a well designed charge), and you can turn the rear evaporator coil's blower fan off anytime you want with no real issues, even though you won't get a very efficient AC system.

Would such a system architecture be feasible in a large coach HVAC system?

I mean, would letting a big enough compressor (such as a Carrier 05K/05G), even one equipped with unloaders (which can seemingly turn a huge compressor into a smaller one, almost like an automotive VDC), feed two huge passenger evaporator coils and one (definitely smaller, car sized, one that would be equipped with a 2 TR TXV) driver cabin evaporator coil at the same time lead to serious issues as soon as you blatantly turn all passenger evaporator coils blowers off? All evaporators have a TXV as the expansion device in this system.

I mean, i don't think oil return issues are primary here, because these huge compressors always have a dedicated oil pump and sump, unlike modern automotive compressors. They're more like A6s than SD709s.
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bohica2xo
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Joined: Wed May 11, 2016 4:12 pm
Location: Las Vegas, NV

Re: Live evap but no air blowing, parallel evaps in coach HVAC

Postby bohica2xo » Mon Mar 23, 2020 7:43 am

Too much oil can be as big a problem as too little.

Multiple evaporators are done on millions of SUV's - and just as may mini-split HVAC units in homes.

Look here for a good "too much oil" tale
https://autoacforum.com/viewtopic.php?f=3&t=2985&hilit=fire+truck

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