As with many people on the forum I am interested in increasing the performance of the air conditioner system. The first thing I thought of was to collect data. So here is what I did. I have 2 two speed units that are from the factory with original thermostats
It was late afternoon when we started the test (4:45), and collected data for 1hr 50 min. The data I was collecting mostly was bedroom and salon thermostat and duct exhaust temperatures on a regular basis to plot the cool down rate. Midway through the test I decided to start recording the carpet near the A/C inlet in the entryway. I also collected the power usage delivered (5400-5200W on high) during the entire test.
It was only 93F outside when I started the test, nowhere near the hottest temperature it gets to in Phoenix.
Here are some of my notes as I would summarize them, but I don't know if this shows the system is good or not:
I am guessing that the a/c units are working well, but never were cold enough for Phoenix.
The coach did not change power consumption much during test but was lower as the temp dropped inside.
Prior to testing, I checked power consumption of each unit. They drew about the same power. My guess is the performance is about the same for the 2 units.
As the indicated thermostat temp dropped, the duct exit temperatures continued to drop as well. Always staying at 30-35 degrees different between thermostat and duct exhaust temp and 20-25 degrees between inlet carpet near the step and duct exhaust.
Because of the location of the thermostats (front mounted on outside wall next to passenger seat, back mounted closet wall interior wall) the front thermostat gets heat from outside and will normally be very different. During test however the exterior next to thermostat did not pick up that heat as it was in the shade the entire time so started out warmer than the back thermostat but ended up about the same.
On low setting, the temp started to rise, but I only did it for 10 minutes at the end of testing
During the entire test, the temperature continued to drop, so the coach would have gotten cooler with more time. It is likely when I anticipate needing air conditioning I should turn it on several hours in advance to precool as much as I can.
Temp inside seemed acceptable, but we were not at 115 and heat soaked from the engine running. At these conditions I know it gets and stays uncomfortably warm.
So what could someone do to improve the cooling? I know that it has been a while since I cleaned the inlet filter and I plan on doing just that to start. In addition:
Possibly changing out a vent for a roof 48V AC would increase cooling capacity. It might be fairly easy to vent out of holes next to refrigerator.
I think I saw somewhere that putting a fan under the coach helps with lowering temp under there to increase heat transfer on the outside unit
Rip the whole basement system out and replace with mini splits like some of the adventurous gurus have done. Lots of nice work out there.
Looking for suggestions
Thanks for taking the time to read, I look forward to comments
Glen
(This post was last modified: 05-23-2024, 04:11 PM by Gnawrocki1.)
There is new technology out there inverter mini splits and now inverter roof air, the old SCS and Cruiseair units are obsolete now. As far as dealing with 100+ temps 30+ days of the year you might have to oversize your units if you decide to convert or add a humidifier to the equation. Steve Magown sent me this.
(05-23-2024, 04:03 PM)Gnawrocki1 Wrote: As with many people on the forum I am interested in increasing the performance of the air conditioner system. The first thing I thought of was to collect data. So here is what I did. I have 2 two speed units that are from the factory with original thermostats
It was late afternoon when we started the test (4:45), and collected data for 1hr 50 min. The data I was collecting mostly was bedroom and salon thermostat and duct exhaust temperatures on a regular basis to plot the cool down rate. Midway through the test I decided to start recording the carpet near the A/C inlet in the entryway. I also collected the power usage delivered (5400-5200W on high) during the entire test.
It was only 93F outside when I started the test, nowhere near the hottest temperature it gets to in Phoenix.
Here are some of my notes as I would summarize them, but I don't know if this shows the system is good or not:
I am guessing that the a/c units are working well, but never were cold enough for Phoenix.
The coach did not change power consumption much during test but was lower as the temp dropped inside.
Prior to testing, I checked power consumption of each unit. They drew about the same power. My guess is the performance is about the same for the 2 units.
As the indicated thermostat temp dropped, the duct exit temperatures continued to drop as well. Always staying at 30-35 degrees different between thermostat and duct exhaust temp and 20-25 degrees between inlet carpet near the step and duct exhaust.
Because of the location of the thermostats (front mounted on outside wall next to passenger seat, back mounted closet wall interior wall) the front thermostat gets heat from outside and will normally be very different. During test however the exterior next to thermostat did not pick up that heat as it was in the shade the entire time so started out warmer than the back thermostat but ended up about the same.
On low setting, the temp started to rise, but I only did it for 10 minutes at the end of testing
During the entire test, the temperature continued to drop, so the coach would have gotten cooler with more time. It is likely when I anticipate needing air conditioning I should turn it on several hours in advance to precool as much as I can.
Temp inside seemed acceptable, but we were not at 115 and heat soaked from the engine running. At these conditions I know it gets and stays uncomfortably warm.
So what could someone do to improve the cooling? I know that it has been a while since I cleaned the inlet filter and I plan on doing just that to start. In addition:
Possibly changing out a vent for a roof 48V AC would increase cooling capacity. It might be fairly easy to vent out of holes next to refrigerator.
I think I saw somewhere that putting a fan under the coach helps with lowering temp under there to increase heat transfer on the outside unit
Rip the whole basement system out and replace with mini splits like some of the adventurous gurus have done. Lots of nice work out there.
Looking for suggestions
Thanks for taking the time to read, I look forward to comments
Glen
Glen, nice work.
A couple of questions, have you done anything to the units? Charged them up? Pulled them out and cleaned the coils? These are some options as well.
Really it also depends on how you plan to use your coach. If you are going to be doing more boondocking you may look into one of those other options. There are quite a few DC air conditioning options out there. I have a buddy that put the Cruise and comfort dc system on his bus and he is quite happy with it. He said they were very helpful in helping him figure out what would work best for him. I am thinking about this as an option, I really thought it was going to be expensive but really they are comparable to the cost of a roof AC now.
If you look at the SCS manual there are some pretty good benchmarks in there to check the AC units before tearing into them. One is the amperage draw per compressor will give you a decent idea if the refrigerant charge is where it needs to be. The second is to measure the inlet and outlet temps. The best you are going to do.
I know my units are charged correctly and the inside and outside coils are clean. Here is some data to help you determine if the existing units can be improved. In 85 degree humid weather the front discharge temp will be 20 degrees lower than the inlet temp, the rear about 12 degrees lower. The rear is always less efficient because of the long ductwork run. In 90 degree LOW humidity weather I have seen the front temp be as much as 40 degrees below the inlet temp, and the rear 20 degrees below.
Stating this another way, with the coach comfortable inside, 75 degrees, the front discharge air will be about 55 degrees, and the rear about 65 degrees with both compressors running in humid southeast conditions. In dry conditions, the front discharge air can be as low as 45 degrees and the rear as low as 55.
Before you ditch a working system, I would do two things. First remove one of the units. This will give yo access to the evap coils for cleaning. You will not believe how nasty they will be. Removing one unit will allow you to crawl into the plenum and clean the other. (Tom is chuckling)
The second thing is to measure the amperage on each leg and compare to the SCS manual. That will give you a rough idea of refrigerant charge. Unless someone has worked on the units, they did not come from the factory with access ports, so it’s not quite so simple as throwing gauges on them.
I am not trying to dissuade you from pursuing other options, just saying to make sure what you have is performing as it should as part of your decision making process.
One more thing, if were are in the south or west, the gen starts when the coach starts meaning if we are rolling the ACs are fired up. Letting the coach heat up and then depending on the SCS units to cool it back down does not work for us. My bride does not like to be hot. Happy wife…….happy driver.
Richard and Rhonda Entrekin
99 Newell, 512
Maverick Hybrid Toad
Inverness, FL (when we're home )
A couple of questions, have you done anything to the units? Charged them up? Pulled them out and cleaned the coils? These are some options as well.
Really it also depends on how you plan to use your coach. If you are going to be doing more boondocking you may look into one of those other options. There are quite a few DC air conditioning options out there. I have a buddy that put the Cruise and comfort dc system on his bus and he is quite happy with it. He said they were very helpful in helping him figure out what would work best for him. I am thinking about this as an option, I really thought it was going to be expensive but really they are comparable to the cost of a roof AC now.
I have not done anything with the existing units, but I don't know about previous owner. I have not charged them up, or pulled out to clean the coils. How hard is it to pull out the unit to clean the coils? Looks heavy. And I will want to do that. I am guessing a lift table will ease this process.
I do like that Tito in the video does use a DC system offloading the AC inverter system. I am guessing that using my 48V batteries as the power for any additional unit would be the right way to go. It is also imperative to minimize additional noise and would look for one of the "quite systems" if they are what they claim.
Most of my use is boondocking, but I do sometimes have hookup when Sara picks our destination. During travel, we normally do not stop at an actual campsite so nights on the way to destination or unhooked.
(This post was last modified: 05-24-2024, 10:43 AM by Gnawrocki1.)
A couple of questions, have you done anything to the units? Charged them up? Pulled them out and cleaned the coils? These are some options as well.
Really it also depends on how you plan to use your coach. If you are going to be doing more boondocking you may look into one of those other options. There are quite a few DC air conditioning options out there. I have a buddy that put the Cruise and comfort dc system on his bus and he is quite happy with it. He said they were very helpful in helping him figure out what would work best for him. I am thinking about this as an option, I really thought it was going to be expensive but really they are comparable to the cost of a roof AC now.
I have not done anything with the existing units, but I don't know about previous owner. I have not charged them up, or pulled out to clean the coils. How hard is it to pull out the unit to clean the coils? Looks heavy. And I will want to do that. I am guessing a lift table will ease this process.
I do like that Tito in the video does use a DC system offloading the AC inverter system. I am guessing that using my 48V batteries as the power for any additional unit would be the right way to go. It is also imperative to minimize additional noise and would look for one of the "quite systems" if they are what they claim.
Most of my use is boondocking, but I do sometimes have hookup when Sara picks our destination. During travel, we normally do not stop at an actual campsite so nights on the way to destination or unhooked.
The units are not too bad to get out. Depending on how big you are, you can actually just slide the unit and spin it to one side and there is enough room to get in to the plenum area. I slid them on to my hand truck but a hydraulic table or motorcycle jack would both work nicely to get the unit out. As Richard said, they do not have service ports on them so to charge them up its a bit of a project, but you may want to verify the amp draws to see how the units are running. One of my units was not running the second compressor because the control board was damaged. I ended up abandoning the control boards and created my own controls based off a house thermostat and relays.
Glen, if you want to stop over and check out CnC's competitor a/c system, you've got to check mine out. I paid 4200 for mine and it can be set to produce 22kBTU on high speed. It will consume 1400watts at high speed and around 960 on regular speed. I keep it on regular speed. So far it is working great. Runs on my 48v system and it is a split system. Easy to install.
(05-25-2024, 04:52 PM)pairodice Wrote: What do you guys clean the coils with? I need to pull mine and clean them and install soft starts…
I picked this up at Lowe's, use it for the house A/C and the coaches units. I put it in a pump sprayer to clean the coils, use it on both inside and outside coils.
I put these on my Wanderlodge units, at the recommendation of my generator supplier (Central Georgia Generator). They work and are alot less money than a soft start. I am going to get these for the SCS units as well, its on my list.
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