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Old 02-12-2019, 05:15 PM   #21
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When the temperature is higher compressor both runs more and the head pressure is higher so that the compressor draws more current.
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Old 02-12-2019, 05:18 PM   #22
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Inverter drives actually change the 60Hz line AC to DC and then change it back to variable frequency 3 Phase AC. This technology is used in A/C units, Washing machines and some refrigerators.
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Old 02-12-2019, 05:20 PM   #23
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The current trend in class B RVs is no propane and no generator. The are putting Lithium Battery packs in them to drive a 12 volt AC unit. The DC motor driving the compressor lends itself to increased efficiency to make that possible. The fact that the heating side is possible is just a plus.
That is the context of my reply to this thread.
I agree that the trend is toward electric only RVs. An efficient heat pump system might be OK for brief heating, but the more common approach is a fuel fired heater since they can also provide hot water.

- - Mike
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Old 06-13-2020, 01:57 PM   #24
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Its all going to end up with 12 volt AC units for RV application since it deletes the need for and inverter running and drawing current.

What's sad is they are ripping customers off over-charging for the 12 volt AC unit then to make maters worse, they keep your stock AC unit, so you're actually paying more then the asking price.

Sort of like when they provide a lithium upgrade they keep your generator!

Stay Safe - Mike
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Old 06-13-2020, 02:14 PM   #25
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Its all going to end up with 12 volt AC units for RV application since it deletes the need for and inverter running and drawing current.

What's sad is they are ripping customers off over-charging for the 12 volt AC unit then to make maters worse, they keep your stock AC unit, so you're actually paying more then the asking price.

Sort of like when they provide a lithium upgrade they keep your generator!

Stay Safe - Mike

Mike, who is "they"? Coachmen is buying ac a/c's and then not using then and installing a pro air? Who does anything like that?

Please explain.

I agree with avanti, the market place sets the price.

Bud
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Old 06-13-2020, 02:22 PM   #26
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They are "any manufacture" that rips off their customers by up-charging for optional features and neglecting to issue due credit for the deleted item. This applies to AC units as well as deleting generators with lithium upgrades as I have outlined many of my authored articles.

I work directly with Xantrex and Lithionics Battery and many other companies in the industry, so I'm up to speed on the cost of these upgrades. Regretfully, even with the economy in shambles from Covid 19 manufactures continue the to squeeze their customers.

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Old 06-13-2020, 04:11 PM   #27
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When the ambiant temperature rises so does the refrigerent pressure in the system. PV=NRT: Pressure X Volume= N (moles of gas) X R (ideal gas constant) X T(temperature in K). Simplified: volume,Moles and gas constant remain the same so P(pressure) is proportional to T(temperature). Since pressure is higher the compressor must work harder to compress the gas to a point where it becomes liquid in the condenser.
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Old 06-13-2020, 09:57 PM   #28
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Since these AC compressors run on DC, some pumps have the capability to run at different speeds when needed for ecomony. Wouldn't it be great if the manufacture provided a means for the owner to select less performance (BTU) say during high temperatures to keep amperage down or even for overnight where it takes less than 6,000 btu to cool a 25-30 ft coach. Regretfully most of these pumps are 20K units which is major over kill for smaller coaches.

Lots of opportunities with 12 volt AC units yet to be discovered.

Mike
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Old 06-13-2020, 11:11 PM   #29
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Since these AC compressors run on DC, some pumps have the capability to run at different speeds when needed for ecomony. Wouldn't it be great if the manufacture provided a means for the owner to select less performance (BTU) say during high temperatures to keep amperage down or even for overnight where it takes less than 6,000 btu to cool a 25-30 ft coach. Regretfully most of these pumps are 20K units which is major over kill for smaller coaches.

Lots of opportunities with 12 volt AC units yet to be discovered.

Mike
The ProAir 12VDC A/C, subject of this thread, does what you have said above.
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Old 06-14-2020, 05:48 PM   #30
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anyone have issues with the proair 12v roof mount air conditioner. 2 weeks since I installed one and now the compressor is seized. I have to wait until Monday to see what's going to happen.
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Old 06-14-2020, 07:47 PM   #31
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anyone have issues with the proair 12v roof mount air conditioner. 2 weeks since I installed one and now the compressor is seized. I have to wait until Monday to see what's going to happen.
I thought these were OEM only for now. Was this a dealer or self install?
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Old 06-14-2020, 11:16 PM   #32
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The ProAir 12VDC A/C, subject of this thread, does what you have said above.
Would You mind interpreting that in English - you lost me!
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Old 06-14-2020, 11:20 PM   #33
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anyone have issues with the proair 12v roof mount air conditioner. 2 weeks since I installed one and now the compressor is seized. I have to wait until Monday to see what's going to happen.

Sorry to hear - how did you determine it was a seized compressor? Could be a number of other things i.e. shorted capacator, fan motor, etc. I would guess they would just change out the whole unit under warranty so we might never know.

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Old 06-15-2020, 12:11 PM   #34
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Would You mind interpreting that in English - you lost me!
Mike, here it is in English:

"Since these AC compressors run on DC, some pumps have the capability to run at different speeds when needed for ecomony. Wouldn't it be great if the manufacture provided a means for the owner to select less performance (BTU) say during high temperatures to keep amperage down or even for overnight where it takes less than 6,000 btu to cool a 25-30 ft coach. Regretfully most of these pumps are 20K units which is major over kill for smaller coaches."
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Old 06-15-2020, 01:26 PM   #35
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OK great - I'm still lost on why you decided to take issue with my reply?
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Old 06-15-2020, 02:51 PM   #36
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I agree that the trend is toward electric only RVs. An efficient heat pump system might be OK for brief heating, but the more common approach is a fuel fired heater since they can also provide hot water.

- - Mike
Boxter my exact feelings as well - when you're out boon-docking and depending on solar to keep the batteries up, a quick run of a modern day furnace like a Truma AquaGo using propane instead of your battery makes sense for heat and water.

Same goes for a refrigerator why have that near-constant 12 volt draw killing the lithium charge or using up what solar you have when an efficient propane Fridge will use and un-detectable amount of propane to save your battery for AC or other needs.

For those who are new to the forum here's a link to my video on this forum titled up-grading your Class B or B+ to lithium. This outlines the advantages of saving your battery with propane appliances as discussed in this thread.

Stay Safe - Mike

https://www.classbforum.com/forums/f...tml#post100729


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Old 06-15-2020, 07:01 PM   #37
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Sorry to hear - how did you determine it was a seized compressor? Could be a number of other things i.e. shorted capacator, fan motor, etc. I would guess they would just change out the whole unit under warranty so we might never know.

Mike
Yeah, it's the compressor. Tested by the shop that installed it and compressor wants to start but bucks. Proair is replacing the compressor. Hopefully this is a rare occurrence
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Old 06-15-2020, 08:25 PM   #38
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Same goes for a refrigerator why have that near-constant 12 volt draw killing the lithium charge or using up what solar you have when an efficient propane Fridge will use and un-detectable amount of propane to save your battery for AC or other needs.

The main reason would be they are a PITA to keep running well, have trouble in hot weather, you need to be quite level. That is plenty enough reason for me to go to a compressor frig.


The heat, yeah, hydrocarbon fuels work very well compared to battery power.
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Old 06-16-2020, 01:17 AM   #39
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Would You mind interpreting that in English - you lost me!
Sure - you said:
"Since these AC compressors run on DC, some pumps have the capability to run at different speeds when needed for ecomony. Wouldn't it be great if the manufacture provided a means for the owner to select less performance (BTU) say during high temperatures to keep amperage down or even for overnight where it takes less than 6,000 btu to cool a 25-30 ft coach."

The Pro Air 12 Volt A/C does just that.
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Old 06-16-2020, 03:04 PM   #40
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Since these AC compressors run on DC, some pumps have the capability to run at different speeds when needed for ecomony. Wouldn't it be great if the manufacture provided a means for the owner to select less performance (BTU) say during high temperatures to keep amperage down or even for overnight where it takes less than 6,000 btu to cool a 25-30 ft coach. Regretfully most of these pumps are 20K units which is major over kill for smaller coaches.

Lots of opportunities with 12 volt AC units yet to be discovered.

Mike
The Firefly control unit for the 12 VDC ProAir in the Galleria switches between "Compressor High" and "Compressor Low" depending on the delta between ambient temp and the set temp.
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