We have two Custom Coach a/c units. They have line voltage thermostats that turn the compressors on & off via large relays.
The a/c units cool great, but there is a problem. They cool too great, so much so that the compressor only runs a short time before reaching the temperature set point, sometimes only a minute or two. This means that even though the temperature is right the compressor isn't running enough to remove humidity from the air.
What I'm looking for is a way to add something to the thermostat circuit which will guarantee a minimum run time, say 5 minutes, even if it means cooling the temperature more than needed.
Any ideas on how to accomplish this?
Why not just run one?
Quote from: chessie4905 on August 20, 2019, 07:54:39 PM
Why not just run one?
We do this when we camp on a 30-amp site, but it doesn't really reach front to back. Our center hallway is really tight and we have to stand a fan in the hallway to get the air to flow through, which essentially blocks the hallway.
can you slow down the air movement fan speed ? if so that will help with the cycle time
dave
If power is available, if you aren't being metered, if you don't care and just want it dry...:
Run a heater concurrently with the AC.
Or get a dehumidifier?
Dehumidifier is good kit, especially when the coach is not being used.
Built in someplace is really trick.
Most funky coaches have been damp inside.
Defend against the stink!
Happy coaching!
Buswarrior
Open the windows?
If the two ac units are next to each other, interconnect the outputs so one running can reach all the coach.
First picture is the front unit. Output is to the right, intake is the grill on the left. The thermostat is just below the intake. There is no other ducting.
Second picture is the rear unit. Grill showing is the output. Thermostat is just above it. Intake is underneath the unit, just behind/above where the TV is located.
The third picture is the narrow hallway between the front and rear of the bus.
Somehow I thought that some type of delay relay would be the simplest solution by just extending the compressor run time.
If the thermostat sensor is in the front of the evaporator like household units, you could put a soda straw over the tube to make the thermostat less sensitive. You could look for an ac thermostat that you could wire in that has a sensitivity adjustment.
The thermostat on these units are line-voltage (120v). The thermostat sends 120v to the compressor relay which controls the compressor. Really simple system - when the thermostat determines that cooling is needed, it completes the circuit to the relay. The relay turns on the compressor. When room temp is met and room is cool, thermostat opens the circuit to relay and compressor stops. The only temperature sensor is inside the thermostat itself, nothing inside the evaporator controls anything.
What I was hoping to find is some type of time delay relay which can be wired to the thermostat circuit going to the main compressor relay. My hope is that this delay relay would be able to keep the relay circuit energized for a set period of time, even after the temperature setting is reached.
There are many types of delay relays out there, but I am getting lost trying to find the type I need.
You need a 120V Delay on Break adjustable relay. Many different brands. Put that term into google and you will find what you are looking for.
As you wire it in, keep in mind two things. One, it must be installed so that the inside and outside (evaporator and condenser) fans run any time the compressor is running. Second, the whole unit will obviously run for the delay time after the tstat turns it off, meaning it will get even cooler.
Quote from: RichardEntrekin on August 21, 2019, 05:08:22 PM
You need a 120V Delay on Break adjustable relay. Many different brands. Put that term into google and you will find what you are looking for.
As you wire it in, keep in mind two things. One, it must be installed so that the inside and outside (evaporator and condenser) fans run any time the compressor is running. Second, the whole unit will obviously run for the delay time after the tstat turns it off, meaning it will get even cooler.
Thanks Richard. Having the proper search term is a great first step.
The evaporator fan is always running if the a/c is turned on. The condenser fan runs anytime the compressor is triggered by the thermostat (the compressor relay also turns on the condenser fan). So, we should be good to go on the fan front.
Yes - I'm aware that we'll drop below the thermostat set point a bit having the compressor run longer than needed solely for cooling. I'll report back once I have a chance to scour the interwebs for a relay.
You'll still have the problem. It will run a little longer, get cooler, and then not come back on for a longer time.
The lengthened run time, less frequently, is likely not going to be sufficient to get the air dried out.
Happy coaching!
Buswarrior
Maybe the actual problem is output air restriction, causing short cycling of the compressor.
we carry a 16" fan similar to this and use it inside and outside to make the air move . works great
we got ours at a hardware store in Florida for $ 30
https://www.grandandtoy.com/ProductDetails?productCode=LLR33982&gclid=CjwKCAjw-vjqBRA6EiwAe8TCk-j056Y0k-9eJCQF4ICNcsCcEOY_M-5xMRS-V0doKLNjQSLQ-j0zCRoCfXMQAvD_BwE
dave
Seems to me the problem might be what you're doing with the cold air. Sort of like my Dyson fan I keep beside my recliner in the house. If I run it on high all the time I get cold even when the house is warm because it blows right where I sit. But if I turn it down or even off, I can find a setting where I'm comfortable. What I mean is, your setup is great for cooling you down any time you are in the middle of the RV, but does it work as well if you are off in a corner somewhere, or say, in the bathroom? Finding ways to circulate the air more evenly through your living space and less directly through the center area might be all the remedy you need. Might be a challenge to do that, ideally you would suck in air from several locations up high and in stagnant corners for instance, and blow it out towards the more remote and warmer parts of the rig to get a more even temperature gradient. That would circulate the humidity laden air through the evaporator and I guarantee you your AC unit is the best dehumidifier you could have, if you just get the moist air to it.
Or, a bunch of small fans might work. But I don't see running the compressor longer as the solution it might look like. If you get the warm, moist, stagnant air to it, it will run longer anyway.
Jim
Quote from: Jim Blackwood on August 22, 2019, 09:18:11 AM
Seems to me the problem might be what you're doing with the cold air. Sort of like my Dyson fan I keep beside my recliner in the house. If I run it on high all the time I get cold even when the house is warm because it blows right where I sit. But if I turn it down or even off, I can find a setting where I'm comfortable. What I mean is, your setup is great for cooling you down any time you are in the middle of the RV, but does it work as well if you are off in a corner somewhere, or say, in the bathroom? Finding ways to circulate the air more evenly through your living space and less directly through the center area might be all the remedy you need. Might be a challenge to do that, ideally you would suck in air from several locations up high and in stagnant corners for instance, and blow it out towards the more remote and warmer parts of the rig to get a more even temperature gradient. That would circulate the humidity laden air through the evaporator and I guarantee you your AC unit is the best dehumidifier you could have, if you just get the moist air to it.
Or, a bunch of small fans might work. But I don't see running the compressor longer as the solution it might look like. If you get the warm, moist, stagnant air to it, it will run longer anyway.
Jim
Yeah, these Custom Coach a/c units will pump out cold air, but they are lousy as far as circulation goes. Just one intake and one outlet, with no ducting. Obviously not easy to add ducting at this point. Perhaps a few well placed fans, but with the limited floor space we have they'd have to be wall mounted to really be convenient. Some thing to think about though.
What'd be the chance of adding in some small overhead cabinets that you could route the air through? Not that it'd be great having the air blow over your dishes and things but it could be a pretty simple remedy.
Jim
Quote from: Jim Blackwood on August 22, 2019, 12:02:55 PM
What'd be the chance of adding in some small overhead cabinets that you could route the air through? Not that it'd be great having the air blow over your dishes and things but it could be a pretty simple remedy.
Jim
Not really possible without destroying the interior.
I see what you mean. But what about some sort of translucent or transparent panel above the right hand (in the photo) cornice board that would let the indirect lighting shine through? That could carry the air forward and distribute it through slots or holes. If you get a significant amount of it to the front and release it there it should help quite a bit.
Jim
I found what I think is a relay that will work on this project. It's adjustable from 3-300 seconds delay in opening a circuit. Right now my system can run the compressor for as little as 30 seconds if the outside temps are not too warm, and I'm hoping that by extending the time by a couple of minutes the cooled air can more fully circulate in the space and the humidity can be removed better.
My thermostat is really nothing more than a 120v on/off switch which opens and closes contacts according to the temperature. This relay will provide for an extension of the time the thermostat keeps the contacts closed, so if I set it for 120 seconds then it will extend the run time by two minutes.
If I understand the wiring on this correctly, the following needs to be done (refer to pdf for diagram):
A) Terminals 2 & 10 will have a constant 120v to run the timer inside the relay. I will tap from the fan power circuit since it's energized whenever the system is turned on.)
B) The thermostat will be connected to terminals 5 & 6 which are labeled 'ext. switch' in the diagram. The thermostat will then be controlling the new relay and not the existing compressor relay.
C) The wires which currently connect to the thermostat will now be connected to terminals 11 & 9. When the thermostat closes the contacts between 5 & 6, the relay will close the terminals between 11 & 9. The relay will then hold them closed for the pre-set time once the thermostat contacts open.
There were simpler relays available, but they worked in the opposite manner by preventing the thermostat from engaging the compressor for a set time after a shut down. That type of relay seemed more like it was designed to prevent the compressor from cycling on too soon after it shut down, but that is not my problem. Right now it will run for 30-45 seconds and then shut down, and it might be 10 minutes or more before it starts again.
(When the temps are warmer, the compressor will run normally and for extended times. That's why I am not worried about something wrong with the system keeping the compressor from running longer).
If your compressor is shutting down after only 30 seconds, it would seem that there is a "short circuit" between the cold air and the return. How many degrees is it cooling the whole cabin in 30 seconds? If cooled air is getting sucked into the return it will cycle like that without sufficiently cooling or dehumidifying the room. Also, the slower the air speed, the more dehumidifying.
There used to be a device at Camping World that was wired in to manage the AC's when there was limited power supply. If activated, it had a timer that alternated between the front and back AC units.
Quote from: Lin on August 25, 2019, 10:54:30 AM
If your compressor is shutting down after only 30 seconds, it would seem that there is a "short circuit" between the cold air and the return. How many degrees is it cooling the whole cabin in 30 seconds? If cooled air is getting sucked into the return it will cycle like that without sufficiently cooling or dehumidifying the room. Also, the slower the air speed, the more dehumidifying.
There used to be a device at Camping World that was wired in to manage the AC's when there was limited power supply. If activated, it had a timer that alternated between the front and back AC units.
The output for the rear a/c is what you see on the wall above the couch. The thermostat is above it. The intake for the a/c is on the horizontal surface above & behind the television. The evaporator unit is inside the upper cabinetry above the TV.
I've tried running it with higher fan speeds and low fan speeds. With the higher fan speeds the cold air makes it across the room enough to bring down the temp across the room. When I run it on slower fan speeds the air seems to short circuit like you describe and go from the outlet right back into the inlet. Medium speed seems to be the ideal.
If I move the thermostat across the room, then it will be in the direct path of the airflow when the fan is on high. Where it is now it's above the airflow.
Not sure that there is an easy solution, since the unit is really over-powered for a room that's only about 7' x 9' in size.
If you can picture the way water flows in a trout stream, apply the same ideas and see if you can find an "eddy" in the airflow where the warm air recirculates and doesn't get sucked back into the inlet. Then put your thermostat near that area so it will be out of the main air flow areas. That should work better than your relay idea. The opposite side of a cabinet for instance. (Since the refrigerator makes heat that might or might not be a good spot.)
Jim
How about replacing that thermostat with a newer or different one. Maybe it is the culprit.Or if it is mounted further away.
Quote from: chessie4905 on August 26, 2019, 12:50:04 PM
How about replacing that thermostat with a newer or different one. Maybe it is the culprit.Or if it is mounted further away.
Original thermostat was a Penn Controls line voltage unit. I replaced it with a brand new one. Penn Controls was bought by Johnson Controls (they put the 'Controls' in Johnson Controls' name), so although the units are identical the new one has the Johnson Controls name on it. These are pricey units, over $100 for the thermostat, but they are good thermostats.
One thing that I did try to do was set the differential so that there would be a gap in temps between calling for cooling and shutting off the compressor, but that is preset on these thermostats and is pretty tight.
I've thought about moving the thermostat, but not sure if it will do any good. There is a thermometer on the wall across the room from the a/c unit, and it usually shows the same temp as the setting on the thermostat. I'd have to hunt around the small room for a spot which is slightly warmer.
My hunch is that the unit is simply too powerful for such a small space when the outside temps are only slightly above the inside temps, which is what's causing the compressor to run for such a short time.
Our household York a/c unit with the fancy touch screen has a setting which can add run time to the compressor beyond what's necessary to hit the temperature set point. They have it listed as a feature to help with humidity control. This is where I got the idea to add the delay relay to the compressor circuit and extend the run time on the compressor just a bit.
I'll be installing the relay in the next week or so when I have time & patience to do it right. I'll report back once it's installed to let you all know how it works.
Another easy one is to run a small electric heater at the same time. Vehicles with automatic hvac do it to temper the air for the temperature set. Just get a small one with 3 heat outputs and/ or fan speeds with thermostats.
Quote from: chessie4905 on August 26, 2019, 01:58:17 PM
Another easy one is to run a small electric heater at the same time. Vehicles with automatic hvac do it to temper the air for the temperature set. Just get a small one with 3 heat outputs and/ or fan speeds with thermostats.
Funny how similar this sounds to how the OTR a/c system tempers the air - compressor runs all the time and the heater core is used to control temp.
This would work when I'm on 50-amp service. The a/c units draw 19 amps each on startup, so I wouldn't try it on 30-amp service, not even with just one a/c unit and one heater, as that would leave me no overhead for the lights, battery charger, etc.
Before the energy crisis in the 70's, it was common to design commercial AC systems with what was called "Reheat". As such that air would be over-cooled and than reheated to the desired supply temp thereby extracting more moisture and providing more control. This practice was stopped because it was considered wasteful in an era of acknowledged limited resources.
Have you tried just shielding the thermostat from the airflow a bit so it will react more to ambient temperature rather than convection? I am not sure what would work best, but even just wrapping it in aluminum foil might slow the reaction time. Just guessing though.
Just wanted to mention another possibility. The thermostat sensor should be in the return air stream. If the sensor is across from the blower and in the supply stream, it will act like you have described.
Don't think he wants to hear that Lin. He has an idea he wants to try, maybe after that hasn't quite met expectations he'll reconsider.
Jim
Lin - I agree that the thermostat placement is not ideal in this install (see photo posted earlier). In addition to the delay relay I'm going to be adding a shield of some type below the thermostat to prevent the air from the a/c outlet from hitting the thermostat. If necessary I can move it to a new location later on, but in a room this small there really are not a lot of options. The side walls are out since they are all windows and/or draperies, and the opposite wall is out since it is in the direct flow of air from the a/c output. In some ways, the current position may be the least-bad option.
Of course you are limited by the configuration that you may have inherited from the PO. In rooftop RV units or home window units the sensor is generally right at the air return. The return air is a good measure of the ambient room temperature. You may not be able to move it to an ideal location. One possible problem with shielding the sensor as you mention or protecting it as I mentioned earlier is that although it will extend the run time before the compressor cycles off, it may also delay the compressor from cycling on. You may be able to compensate for that by playing with the on/off gap in your thermostat, since I think you mentioned that it was adjustable.
The on/off gap is not adjustable. I was hoping it was, but it's preset.
The air return on this unit is on the horizontal surface under the a/c unit. Hard to see in the photo, but it's above and behind the TV. While that would be the ideal place to mount the thermostat, it would then be nearly impossible to see or adjust without doing gymnastics.
I'm going to try the relay and shielding and see where to go from there.
Thanks for all your comments.
Set this in front of the air intake. Only draws 200 watts.
https://www.amazon.com/Lasko-102-Personal-Ceramic-Heater/dp/B00538G5PI/ref=sr_1_26?gclid=EAIaIQobChMI5f_Bvqmp5AIVC6_ICh2qjwl7EAAYASAAEgKHvfD_BwE&hvadid=295586692239&hvdev=t&hvlocphy=9006537&hvnetw=g&hvpos=1t1&hvqmt=b&hvrand=8801101653989429424&hvtargid=kwd-374833943687&hydadcr=29443_10730058&keywords=150+watt+space+heater&qid=1567124450&s=gateway&sr=8-26
I'd suggest buying a 20 to 40ft length of wire for your thermostat (it sounds like lamp cord could work, maybe even an extension cord) and then try putting it in various locations in the coach until you find one that works. Then figure out how to mount it there permanently. Try corners that are out of the direct airflow, high locations, the opposite end, and spots where you think dead air and return air might be. A little trial and error goes a long way.
Jim
Moving the thermostat isn't going to fix anything.
The temperature in the coach/zones was not the complaint.
Short cycling of the compressor, as every AC does when the load is small, and the resulting dampness, was where this started.
But keep typing, the Google ad dollars are rolling in for Gary!
Happy coaching!
Buswarrior
BW I rarely disagree with you but this time I must. If it were accurate then the thermostat could be put in the center of the discharge vent and we know that doesn't work because nobody does that.
If you have an accurate enough thermometer (and humidity tester) you could go around the bus and find temperature gradients. It will be warmer by the windows for instance. We all know this is true, just the same as it is colder by the windows in winter. So for instance, if you stuck the thermostat on the window the AC would stay on longer because it would take longer to get the window cool. Now granted once you have it cool it should cycle a bit faster but as that is where most of the heat comes in, it won't cycle as fast as it does now. What's it cost to try it? A pair of skinny wires and a little time. That is way easier than splicing in relays. And if it doesn't work you've lost nothing.
Jim
The room is only about 7' x 9' with windows & drapes down two of the four walls. The opposite wall from the a/c unit is in the direct flow of the output. Not many options.
BW has the right thought here - the unit is oversized once the room is cooled off, especially when it is not too hot outside and/or humidity is high. Best solution would be a multi stage compressor, but that isn't going to happen.
I figure it will take less than an hour to install the relay. That option does the least harm to the cabinetry, and I will try it before moving to other approaches. This concept works well in our S & B system, so I hope that it will on the bus as well.
The result of running the compressor longer will be cooler temperatures inside, initially, and then the same short cycling at that lower temperature.
The inside temp will now be uncomfortable for the inhabitants, and it will still be damp.
We're chasing the humidity, not the temperature.
Traditional AC has always been challenged to do this under low load conditions. Adding heat is the only solution.
A dehumidifier does this by having all the refrigeration equipment blowing the heat of the condenser back into the same spaces as the evaporator. A dehumidifier by itself will warm a space to a small degree.
Some of the mini-splits offer a dehumidifier setting, which is really handy for a busnut.
Or, in our case here, a $20 cube heater running in the space to put an artificial load on the AC, so it runs more, and dries the air along the way.
BUT... there's NOtHING WRONG with experimenting and fooling around to see what various equipment might be able to squeeze out, performance wise. If Richard can fool his particular unit into doing just enough to make him happy, then the whole exercise has been worth it.
And if it doesn't, he still had fun messing around, and it kept him out of the bar?
Happy coaching!
Buswarrior
Sure, worth trying. What's the worst that could happen?
Jim
Having fun experimenting, for sure.
Even if the delay relay doesn't fix the humidity problem it will keep the compressor from cycling on for such a short period of time and will serve as somewhat of an on/off gap (which on my thermostat setup is not adjustable.) I know the temp will drop a bit more than the thermostat set point with the extended run time, and I also know what the compressor will stay off a bit longer between runs since it now has to climb back up further. That little feature in itself will be welcome, as the frequent on/off of the compressor isn't conducive to sleeping since the relay in the a/c compressor unit downstairs makes a loud noise every time it engages. (It's been checked - it's normal - it's a downside of using a commercial refrigeration unit in an application like this.) The noise is not my primary concern, but maybe the delay relay will help with that even if not with the humidity.
Or you could crack a window open. Adjust the crack till the desired result is achieved. Or install a speed control on blower motor.
Quote from: chessie4905 on August 30, 2019, 11:24:51 AM
Or you could crack a window open. Adjust the crack till the desired result is achieved. Or install a speed control on blower motor.
Wouldn't that just let more humidity inside?
Just a thought here.
The Mini Spit in my bus is controlled by a remote.
The temperature can be controlled either by an internal sensor in the return of the Minisplit unit, or a setting on the remote called "Follow me" that is controlled by a temperature sensor in the remote control.
Usually we leave it on the internal sensor, but on occasion use the sensor in the remote.
Something like this could work for you, a quick Amazon search came up with this.
https://www.amazon.com/Nashone-Temperature-Controller-Thermostat-thermostat/dp/B071NG8MZK?ref_=fsclp_pl_dp_9 (https://www.amazon.com/Nashone-Temperature-Controller-Thermostat-thermostat/dp/B071NG8MZK?ref_=fsclp_pl_dp_9)
Peter
Not a bad thought Peter. Looks like there are a number of such remote sensor thermostats out there. Should the delay relay not work as I hope, this gives me another option.
Delay relay has been installed. Wasn't really that difficult, as there was 120v available at a terminal strip in the evaporator cabinet which was fed by the circuit breaker for the ventilation fan. Connected the 120v to run the relay, and then re-routed the thermostat wires to go through the relay. I can now set a delay of 3-300 seconds and keep the compressor from running for only 30-45 seconds, which happened when the weather was not too hot and the room had come to temp.
I'll run it for a few weeks and see if it helps. Hopefully I will be able to report on success or failure at rally in Blytheville.
So now it's next season and I've had a chance to run the a/c a bit with the new delay relay installed. I can say for certain that keeping the compressor running for longer has helped. With the weather only marginally hot, especially at night, it was only running for about 30 seconds at a time before. Now it runs 3 minutes at the minimum. Doesn't sound like a big difference, but it does help remove more humidity from the air.
I think in the end the problem is that the a/c unit is just too large for the small space of the back bedroom. Being too large is no better than being too small - an a/c unit needs to be sized right. Perhaps in Texas or Arizona this would be appropriate, but not for use up here in the north.
:^
MY CC has remote sensors and a weird thermostat to control 3 zones with the AquaHot heat,heat pumps and AC,I am about to figure it out though everyone tells me the thermostats on the Coleman Roof tops will only turn the compressor off and the fan still blows,if I set the zone to automatic when the compressor kicks out on cool or heat the fan will run for less than 2 minutes then shut off,If I set the fan setting on high or low when the compressor kicks out the fans never stop what is up with that ?
You should be able to blend heated air with the cooled air to control outlet temp, get all the dehumidification without over cooling, just like in cars.
Quote from: chessie4905 on June 27, 2020, 03:25:01 PM
You should be able to blend heated air with the cooled air to control outlet temp, get all the dehumidification without over cooling, just like in cars.
He could probably do that if the unit had a heat exchanger and both used 1 common duct like automobiles I doubt he has that luxury
Quote from: luvrbus on June 27, 2020, 01:16:19 PM
MY CC has remote sensors and a weird thermostat to control 3 zones with the AquaHot heat,heat pumps and AC,I am about to figure it out though everyone tells me the thermostats on the Coleman Roof tops will only turn the compressor off and the fan still blows,if I set the zone to automatic when the compressor kicks out on cool or heat the fan will run for less than 2 minutes then shut off,If I set the fan setting on high or low when the compressor kicks out the fans never stop what is up with that ?
I can't be 100% certain without hands on with your thermostats. But if they are like mine, they behave exactly as described on purpose. On the Auto setting, the fan comes on when the temp is more than 1 degree from the setpoint. A minute or so later, the compressor kicks in, when the tstat reaches setpoint, the comp turns off and the fan runs for another minute or so. The purpose of the fan coming on early is ensure the compressor doesn't generate a high head pressure on startup, and it runs for an additional minute to extract the last bit of cool from the evaporator.
When you put the tstat in high or low manual the fan runs all the time to circulate air continuously, and the compressor cycles based on the difference between the air temp and the setpoint. I find this setting VERY useful while driving because it minimizes the temp swings in coach due to the AC coming on and off.
I hope this explains "what's up with that ".
Thanks for the explanation Richard that is exactly the way mine works in all 3 zones Lol I thought the tstat maybe screwed up
Quote from: chessie4905 on June 27, 2020, 03:25:01 PM
You should be able to blend heated air with the cooled air to control outlet temp, get all the dehumidification without over cooling, just like in cars.
Not sure where the heated air would come from - the a/c units basically operate like a mini split. All they do inside the coach is blow air across the evaporator coil. No heat coil involved.
Quote from: RichardEntrekin on June 27, 2020, 06:15:50 PM
I can't be 100% certain without hands on with your thermostats. But if they are like mine, they behave exactly as described on purpose. On the Auto setting, the fan comes on when the temp is more than 1 degree from the setpoint. A minute or so later, the compressor kicks in, when the tstat reaches setpoint, the comp turns off and the fan runs for another minute or so. The purpose of the fan coming on early is ensure the compressor doesn't generate a high head pressure on startup, and it runs for an additional minute to extract the last bit of cool from the evaporator.
When you put the tstat in high or low manual the fan runs all the time to circulate air continuously, and the compressor cycles based on the difference between the air temp and the setpoint. I find this setting VERY useful while driving because it minimizes the temp swings in coach due to the AC coming on and off.
I hope this explains "what's up with that ".
mine works the same way as well for all 3 units
dave
Sorry, I thought you were talking about the coach air, not your cruiseaires.
Quote from: chessie4905 on June 28, 2020, 06:47:13 AM
Sorry, I thought you were talking about the coach air, not your cruiseaires.
Ok - now your comment makes perfect sense. What you suggested is exactly how the OTR system works.
The problem I'm having is with the house units - Custom Coach built these things using commercial refrigeration parts, and I can turn the bus into a meat locker if I want. The problem comes when I want to hold a steady temp of about 70 and also keep the humidity down. They just cool too fast to properly remove enough moisture.
Could you add some kind of heating coil inside of ac output duct and control it with a thermostat or something. May be the guts out of a cube heater or...