Upgrading my Air Conditioning front HVAC system

[PaulRV]

I have a 97 Windsor Monaco. My engine driven AC has a leak. I ordered a couple of packets of dye to find the leak. I was also thinking of an alternate solution. Instead of 50 feet of line and a dash coil that is difficult to access, I was thinking about replacing the compressor with an alternator and adding an electric powered AC unit. Has anyone tried this with success? My other solution is to just run the LP generator.

[Rikadoo]

Electric compressors, great idea, adding another alternator ehhhh! From what i hear the compressors have a pretty good amp draw, some hot rodders are using them with what appears to be good success when they proudly display what they have done, but nothing long term after the car has been on the road in real time. Im thinkin if i was to do that i would have the unit close to the evaporator, well then you need the condencer close as well, cause im not sure the compressor would like the distance. Now i dont or i should say i have NOT researched the compressor specs cause frankly i dont have tbe $$$ to perform research let alone if it fails then need to try plan “B” or c or ??  My thoughts on the electric portion, is IF you had good batteries,  that with just the engine running by itself down the road is 30 to 40 amps that if your compressor was to draw 65 amps, that though its a fair load your still under the amps of a good health leese nevel 185 amp alternator. I would use a amp meter to get a good reading of running with fully charged batteries then add the compressor amps an make a determination as to the health of your alternator, an decide from there. Keep me in the loop, cause the idea has merit👍👍👍

[cbr046]

How many BTU does a dash air put out?  If you can't move the condenser up forward you'll lose the advantages of an electric-compressor unit IMO.

- bob

[wamcneil]

There was a guy on here last year named Ted that was planning to install a 120v condensing unit up front driven by the inverter and replaced his engine compressor with a 2nd alternator to help supply the extra power needed. I don’t think he got around to installing the compressor, but he spent a lot of time planning the project and was thoroughly convinced that the solution was practical. I think a 120v compressor would probably be a lot more cost effective than 12v.

Personally… I would just run the LP generator 
 

[Rikadoo]

Ya know i understand the desire for dash air, cause when im driving its a relief to have cool air to help me keep a level head. Which is why every 18 wheeler has dash air in it,  ( i dont remember what year however i believe DOT actually made that a mandate) yet as good an cold as i have made my dash air work, last year when a buddie and I traveled to south carolia he would say on more than 1 ocassion “its getting hot in here”. Which my reaction was to fire up the generator an turn on the roof air, when you look at the seating up front of a 2003 HR Endeavor when you have the passenger seat back far enough to be able to enjoy having it in recliner position the dash air just cant blow enough volume to reach it. So as a driver i believe it is important to have a proper amount of cool air flow that helps ME stay “cool under pressure” however i cant help but wonder could that be accomplished using the roof air with a dash fan (which my rig does not have) circulating the air around me. An frankly i cant help but wonder would the fuel consumption not be similarly the same givin your only running just one of the roof ac units???

[Tom Cherry]

My thoughts….based on a lot of research as well as watching the “NEW” Power Management Modules….or the PMM or electrical system’s version of the engine’s ECM.  This is OLD technology….as in GM first put it out circa 2013.  But we have a 2014 Caddy ATS and a 2016 Vette.

The main drag from the HVAC Air Compressor is HP DRAIN….as in MPG drop.  The clutch on the compressor has minimum draw. Tesla got rid of the “toaster” for heat and went with a Heat Pump.

Energy is Energy….can’t be destroyed or created.  So, if you add an electric compressor, it will need power.  Refer trucks have Generators.  They run on AC…not DC.  More efficient for a diesel Genny to power an conventional high efficiency AC chiller.

Just, after almost 9 years, replaced the AGM in the Caddy.  Watching the voltmeter like a hawk….as well as curiosity…. The PMM will shut down charging…as in LOAD SHEDDING and the system voltage will drop into the 12.4 - 12.6.  Therefore the battery is actually POWERING the electrical system….then when the load increases as in the headlights are on or the AC compressor kicks in…..it goes up.  The FLOAT charge point is 13.4/5…NOT unlike that of our MH.

BUT, unlike our MH where the VR is always at 13.8 - 14.0…..the PMM allows the Alternator to “rest” or idle.  

FWIW.  Delphi Technologies….the original Electric/Electronics division of GM, now spun off…but the “daddy rabbit” of automotive technology says….

Most of the newer hybrids have changed to an inverter compressor which is a high voltage electrical motor. The motor runs on high voltage AC supplied by the A/C inverter located in the inverter or affixed to the AC compressor itself so compressor operation does not depend on the engine.

Thus, one should be looking at an Inverter Compressor.  I THINK that Samsung and others have gone to this system in their refrigerators.  Might want to google. Maybe there is an AC powered one and then you would use your front Genny or the Inverter to power it.

[PaulRV]

Thank you all. If the leak is not an easy fix, I will run the LP generator.

[Tom Cherry]

31 minutes ago, Rikadoo said:

Ya know i understand the desire for dash air, cause when im driving its a relief to have cool air to help me keep a level head. Which is why every 18 wheeler has dash air in it,  ( i dont remember what year however i believe DOT actually made that a mandate) yet as good an cold as i have made my dash air work, last year when a buddie and I traveled to south carolia he would say on more than 1 ocassion “its getting hot in here”. Which my reaction was to fire up the generator an turn on the roof air, when you look at the seating up front of a 2003 HR Endeavor when you have the passenger seat back far enough to be able to enjoy having it in recliner position the dash air just cant blow enough volume to reach it. So as a driver i believe it is important to have a proper amount of cool air flow that helps ME stay “cool under pressure” however i cant help but wonder could that be accomplished using the roof air with a dash fan (which my rig does not have) circulating the air around me. An frankly i cant help but wonder would the fuel consumption not be similarly the same givin your only running just one of the roof ac units???

MANY folks have run studies, me included.  Its cheaper to run the rooftops.  I see as much as a 7% drop in MPG. 

Look up the specs on your genny.  Use the 50% load number.  Translate that in to gallons (pounds?) and cost per hour.  Then, assume 5, 7.5 & 10% MPG decrease…at 60 MPH for an hour.  The math always supports the overheads.  Truckers are NOT cooling the volume.  My Vette will freeze your whatevers…..but, ask folks with a long SUV….

MY front is dead.  I ran the Genny.  I have a small 12” oscillator fan between the front seats, anchored down with a 10# hand weight.  Keeps me cool…even driving directly into the sun…

[Benjamin]

It's hard to understand how running the generator and rooftop air would result in more MPG than the dash air. A small diesel at low load should be less efficient than the marginal load on a medium diesel already running, say going from 100hp load to 102hp load.  That's ignoring the electrical generation loss and the electric motor loss, or assuming they equal the reduced cooling efficiency of the engine driven system.  I don't know what EER a typical vehicle A/C runs at, I assume not very good because the technology SEEMS the same as it's been for decades.  On the other hand, rooftop air units aren't known for great efficiency either, I'd assume similar to window A/C at around 10 EER. 

Trucks use auxiliary power units, a Thermoking is a two cylinder 10hp diesel driving a conventional automotive compressor and alternator.  While newer ones use batteries and heat pumps.  Inverter compressors are common in mini split heat pumps, and are beginning to be more common in window units, maybe they'll make it to rooftop units, or already have?

edit: on second thought, if the fan came on full speed with A/C, that could be the difference. 

Edited August 31 by Benjamin