A/C Upgrade or how do I work the one I have?

kylecm

Member
Okay, I am ready for the stupid award. However, here it goes :thinking:

Model: Thor Siesta Sprinter SA24
Year: 2015

A/C - Dometic 641915C851J0 / 991762746 (I have no idea if this is a Penguin or Brisk or other)
BTU 13,5

Controller: Dometic Single Zone LCD Control Thermostat

Problem:

Outside temperature about 84 F
Inside Temperature about 75-80F

Question 1: I have read almost all of the forums and the manuals. The golden nugget is set the thermostat at 70 and the fan anything but low. So here is the stupid part. I push the on/off button, then A/C kicks on, I select the + or - to get it to 70 F. But how do I control the fan? It is already running. What am I doing wrong??? How do I change the speed of the fan? The mode on mine is Fan / Cool / Furnace - If I select Fan, hi / low / Au (auto), but then I running the fan only right? If I choose Cool, all I can select after that is +/- for temp.

Question 2: Is the A/C unit I have a good one? Or did Thor just put the cheapest thing on the market on top of the RV? Even with the central vent shut no air comes out of the front vents. My local RV Dealer Reines in Manassas VA said that was normal. Sounded stupid to me, but heck they are the experts right?

Should I upgrade the AC unit to something better? A 15,000 BTU.

Thoughts? Ugh... so last night at 1:30 AM when my wife was smothering (okay a little exaggeration), she kicked me out of bed and said, let's go home. Weekend shot 'cause I don't know how to run an A/C :laughing:

Thanks

Chuck
 

stevehar

2015 Thor Siesta 24SR
Chuck, here is the manual for the thermostat, when you change the fan mode it will apply to the cool/heat mode depending on what you have set. I use auto most of the time, because I like some peace and quiet once in a while...I use high to get it to cool down quicker.

Check the model # again, I have a 2015 siesta and the build sheet says model 640315 A/C, ROOF, 13.5K BTU, 2 SPEED ROTARY, PENGUIN, BLACK

Here is a link to Dometic http://www.dometic.com/International/Download/Manuals/

View attachment Single Zone LCD Thermostat.pdf
 

kylecm

Member
Steve,

Thanks for the pdf. I will check it out and give it a try. I will check the build sheet to see what it says (I think there is a copy hanging in the closet). I have to keep the RV at a lot about 15 miles from the house, so I will check that next weekend. 15 miles in Northern VA is a one hour trip :)

The part number that I had was from the panel if you remove the filter inside the coach. It appears as if I need to look at the model number up on top of the RV. Once again, will do that next weekend. However, it is a 13.5 btu and has a black cowling, so must be the same as yours.

Since we have the same vehicle. Do you get airflow out of the two vents in the front of the vehicle? Does you A/C keep your vehicle around 70 when the outside temp is 90+

Thanks

Chuck
 

Attachments

stevehar

2015 Thor Siesta 24SR
I get very little air out of the front vents. If I close the vents above the bed there is a little more air. I put a small fan up there in to help circulate the air. Being in AZ the roof can get pretty toasty. This is our 2nd summer traveling and sometimes we wish we had a bigger unit.

Steve
 

GV-Citation

New member
It is a well known issue to have the front vents not work properly on a Thor Chateau Citation. There is a restriction in getting the air flow around the Dometic Skylight. Sometimes the ducts were not installed correctly or have come loose. With determination, the warranty dealer can take the roof apart and improve the situation by making corrections. Another point is to close the damper right by the AC return. This will force more air to the other ducts throughout the coach.

The AC is probably best used with the fan on au = auto. In the Cool mode the fan speed will be automatically set depending upon the degrees from the set point to the coach temperature per the manual. The fan will be on High if the set point is far from the actual temperature and switched to Low as the actual temperature comes closer to the set point.

Also, curious is if the fan is left on Low or High it will come one when the furnace is used. This is supposed to help circulate the air. However, again I have found it best to leave the fan on au=auto so that the noisy AC fan does not come on. The furnace is one thing that works very well in the RV without any problems.
 

Attachments

ksrow

New member
I get very little air out of the front vents. If I close the vents above the bed there is a little more air. I put a small fan up there in to help circulate the air. Being in AZ the roof can get pretty toasty. This is our 2nd summer traveling and sometimes we wish we had a bigger unit.

Steve
Hey Steve
You probably don't want to know this but I will tell you anyway. We had the same problem with it getting to hot over the cab. Turns out that there is NO INSULATION between the inner ceiling panels and the fiberglass cap. You can tell by putting you hand on the side wall up above the the upper bed around the side windows on a hot sunny day. The Cure? I took the side panels down as well as the ceiling above the the upper bed forward of the skylight. Next, I used the silver double sided 1/4 inch air break insulation you can buy at (Lowe's http://www.lowes.com/pd/Reflectix-100-sq-ft-Reflective-Roll-Insulation-48-in-W-x-25-ft-L/3011906) I used 3M spray adhesive to attach it to the back of the inner panels and again to the inside of the fiberglass shell. When all reassembled the air break between the two inner panels and outer shell makes a great insulation. This is not for the faint of heart and you must be pretty handy to take on the job. Ultimately though it will improve your heat problem in the summer and winter to an exceptional degree. I also was able to greatly improve the air flow problem as well. The vent boxes were not properly secured and sealed so a great deal of the cold air was venting out into the uninsulated solar heated space between the inner panels and outer fiberglass cap. The job took me about one and a half days because I did it by myself. If you have a second helper you could do it in a day and getting the ceiling panel and side panels back up alone is a bear. The option is to take it to the dealer and get out your check book because I doubt that they will warranty any of it. If you have any other questions message me. GOOD LUCK Steve R
 

ksrow

New member
Hey Steve
You probably don't want to know this but I will tell you anyway. We had the same problem with it getting to hot over the cab. Turns out that there is NO INSULATION between the inner ceiling panels and the fiberglass cap. You can tell by putting you hand on the side wall up above the the upper bed around the side windows on a hot sunny day. The Cure? I took the side panels down as well as the ceiling above the the upper bed forward of the skylight. Next, I used the silver double sided 1/4 inch air break insulation you can buy at (Lowe's http://www.lowes.com/pd/Reflectix-100-sq-ft-Reflective-Roll-Insulation-48-in-W-x-25-ft-L/3011906) I used 3M spray adhesive to attach it to the back of the inner panels and again to the inside of the fiberglass shell. When all reassembled the air break between the two inner panels and outer shell makes a great insulation. This is not for the faint of heart and you must be pretty handy to take on the job. Ultimately though it will improve your heat problem in the summer and winter to an exceptional degree. I also was able to greatly improve the air flow problem as well. The vent boxes were not properly secured and sealed so a great deal of the cold air was venting out into the uninsulated solar heated space between the inner panels and outer fiberglass cap. The job took me about one and a half days because I did it by myself. If you have a second helper you could do it in a day and getting the ceiling panel and side panels back up alone is a bear. The option is to take it to the dealer and get out your check book because I doubt that they will warranty any of it. If you have any other questions message me. GOOD LUCK Steve R
https://photos.google.com/album/AF1.../AF1QipO6jRetm2atYOdrHLKyy9TQJNm_zQCDCOaGtEQc
 

Old Crows

Calypso 2014 View Profile
Chuck, no RV AC will adequately cool w/out good air flow. As others have said here and on other threads....the ductwork needs checking/R &R and insulation maybe lacking or inadequate.

For now, I'd turn it ON & Auto & set the thermostat & forget the fan speed. Got a thermometer? The difference between the ambient air temp at the intake and the cold air vents should be about 20F or a bit less if its working right.

You are in VA, no? Hot and humid. It is going to take awhile to bring the temp down with a 12.5 BTU unit. And depending, it might run for a few hours or more slowly working down the temp and humidity. Air circulattion is critical....if the ducted vents are not blowing strongly it will likely not be effective...as you know.

Pull the filter/grill to see that the filters are correct and that there's nothing blocking the internal air return. Been know to have FOD sucked into them due to poor housekeeping during construction.

Comment: a 12.5 BTU A/C sounds a bit light but doable if you are careful. Provided you have excellent air circulation. A 15 15+ would appear to be a better choice in hot humid climates.....
 

slvmart

New member
Chuck ... we have a brand new 2014 24SR. I had the same problem with the AC. And other than the comment, above, about the lack of insulation, this is another things you may not want to hear. This is especially true if your coach is out of warranty. The lack of A/C air flow, as determined by THOR Factory Service center :

Concern: 14. C/S: FRONT A/C DUCTS, NEAR CAB OVER DO NOT HAVE AIR FLOW
Cause: DUCT WORK NEEDS TO SEALED PROPERLY, LEAKING AIR.
...
Correction: REMOVED SKYLIGHT COVER TO SEAL OFF DUCT WORK AS NEEDED.
REINSTALLED SKYLIGHT AND TESTED, MORE AIR FLOW IS COMING THRU.

As far as the insulation, the cabover is not the only place lacking. When I was installing a external antenna for the cab radio, I removed the large trim panel where the chassis cab interfaces with the coach. Low and behold, there is absolutely no insulation behind that panel either. Based on this it would seem that if there is any insulation in the cab area, it would only be where MB has installed it.
 

kylecm

Member
Still two years down the road and my A/C sucks :)

First thing, I pulled the skylight down and one of the duct hoses was cut in half. I think it just came from thor that way. So with some duct tape repaired. I also had numerous holes in the duct hoses on the other side.

Second, After pulling the A/C panel down from the ceiling, I noticed that there was almost no duct tape or anything for that matter that joined the A/C to the actual duct work. It was like the service center built the coach and then just put the A/C and never checked if it lined up. More duct tape and now that is sealed.

Thursday I am going to tackle the overhead cab area to insulate like ksrow suggested.

I am still debating on whether or not to pull the 13.5 penguin and put a 15k blizzard. Any thoughts?

As far as the standard Dometic thermostat. I hate that it does not show the room temperature, only the set temperature. Has anyone replaced theirs with one that shows both?

Thanks

Chuck
 

Hooligan2

Member
2016 Siesta Sprinter 24ST-- My original 13.5 AC failed, I replaced with 15K btu (warranty +$$). Some improvement..(My opinion- not worth the expense just for the change).
However my OEM thermostat (dual zone) does show inside temp, upper right button. Fan selection- If low med high selected, fan runs continuously, AC compressor cycles on and off so satisfy temperature setting. In Auto fan runs with the compressor. (starts just before compressor and shuts of several seconds after compressor)
Manual for my thermostat has details. thermostat-dualzonecomfortcontrol-dometic-operatinginstructions.pdf
 

Top Bottom