It may be time for a new A/C and I have a coupla questions ...

[mayfair]

OK I got to jump in here....
First I'm a retired HVAC/R service tech...that being said..
Yes it's a sealed unit and NO it can be serviced and re-charged...but might not be worth doing..
The USED unit you bought was probably [used] for a reason...sorry pal...
Most a/c's should discharge air around 15-20 degrees colder than room temp..colder means not enough air flow across the coil, read dirty or restricted flow or fan speed too slow..
If it is much warmer discharge it is usually due to a low charge but can be the load is too great or the fan is too fast[shouldn't be that but if the air doesn't stay on the coil long enough the BTU transfer won't happen].
As for the line voltage thermostat I see no reason why you can't use one..just remember it has to be rated to handle the amp [wattage] of the unit including the starting surge AND it has to be a COOLING thermostat..most line voltage t'stats you'll find in Lowes or such are probably for heating...you want the switch action to BREAK on a temperature drop...heating ones MAKE on a temperature drop..
Most a/c's are not designed to run a room much cooler than 70 degrees [I know some go to 60 but they are way beyond their design]
Also FYI when an a/c first starts as much as 80% of it's load is the moisture in the air and will at first seem less effective...so keep windows closed and o/s air infiltration to a minimum and let the unit lower the room humidity.. as the humidity level drops you will be more comfortable and the temperature will drop.
I could/can never convince my Mother to close windows..wants to let HOT AIR OUT..and I'm full it...sigh ...
Another ALSO...the newer units operate more efficiently and usually have fan auto/on  controls..so if you decide to replace the replacement, sorry for that, look long and hard at biting the bullet and good luck..
Sorry about the soap-box and hope I don't offend..

George

Thanks for the reply George - all input is appreciated! 

I hear ya about buying the used unit, but I took a chance on it only because the place where I bought it from was kinda like an rv junkyard of sorts. They have a bunch of campers there that they part out for - whatever. Some of the campers even looked like they had been in wrecks. The unit that I bought was very clean and looked a heluva lot newer than mine, however I can't find a date on either the one that I bought or my old one so who knows. Maybe I bought a clunker, maybe I didn't, either way spending $200 didn't really kill me and I got a heluva eduction for it. Prior to buying the unit I was very intimidated by the whole process of doing the job myself. Having done the job now I would have been PISSED had I spent that same $200 to have someone else do the job, so that alone was worth the ca-ching. It was SOOOOO simple!

The thermometer that I used to test the temp coming out of the unit I placed right in the vent and it read about 70. This is what I used http://ecx.images-amazon.com/images/I/31wj1yG4jIL._SL500_AA300_.jpg Had I placed the thermometer on the kitchen table or wherever the temp would have been higher. The camper used to get a lot cooler and that is why I started this whole process. My old unit as well as this newer unit both removed moisture from the room as both dripped water from them as they were running. I throughly cleaned the new unit prior to putting ti up there but to be honest with you it really wasn't that dirty at all.

I was leaning now towards the t-stat only because I could hear it "click" to turn the compressor on, however it would click again after a minute of so indicating that the desired temp had been reached whereas in reality that wasn't the case. Do you agree that it could be the stat? If I can find one, I don't mind spending the dough on my continued education. I actually kinda dig gettin into it all  - haha!

Stupid Question of the Day - When I bought the used unit it was laying on it's side. The dealer told me to wait an hour or two before running it so that the freon and oils could settle which I did. Do you think that perhaps I should have let it sit longer before running it?

Thanks again for everyone's help! 

 

[Mark R.]

sealed unit , not rely, tech can install a charge port. I have found PPL parts in TX have always been fast shipper with best price, I think I got the name correct.

http://www.pplmotorhomes.com/parts/rv-air-conditioner-parts-1.htm

 

[Icemaker]

OK---there is a capillary tube from the thermostat that cycles the unit...often they are on the evaporator coil and help to keep the compressor from freezing the coil along w/controlling the discharge temperature. Look for it touching the coil. Most are in a plastic holder that keeps the sender [the whole cap tube is part of the sensing unit] from being in direct contact but still close and in the return airstream.
The coil [evap] should start sweating and not icing up. I think the run-time of the compressor should be longer than a minute but I'm not a window/rv a/c tech expert.
The return air is the air sucked in, probably the center and thru the filter(s), and ducted right to the evap coil. there should be no spillage of discharge air leaking directly back to the evap. That would cause short cycling and reduced capacity too.
As for the oil/freon separation it is more to prevent oil from being in the piston area and doing damage. Think hydraulic damage much like sucking water into an engine would do. If you had not done right it would have been apparent so I think your safe there.
Hope some of this helps.

George

 

[mayfair]

OK---there is a capillary tube from the thermostat that cycles the unit...often they are on the evaporator coil and help to keep the compressor from freezing the coil along w/controlling the discharge temperature. Look for it touching the coil. Most are in a plastic holder that keeps the sender [the whole cap tube is part of the sensing unit] from being in direct contact but still close and in the return airstream.

Here's what I thought was weird about the whole process ... When I separated the rooftop portion (compressor +) from the inside portion (Speed control and t-stat) I was fully expecting to see that cap tube that you mentioned and it wasn't there. Well, it kinda wasn't there.

This may be hard to explain so bear with me.
I was kinda expecting to see a small copper tube going from the t-stat to SOMETHING of the outside portion, but there was nothing. The only thing connecting the two parts was 5 wires bundled in one connector that all went to the t-stat side. Once unplugged and the screws removed, the two portions separated.

I'm guessing that this is my replacement stat.

http://www.americanrvcompany.com/zoomify.asp?catalogid=10466&img=assets/images/colemanair/6703-3401.jpg

If you look at the pic, it shows the small copper "wire" that I was talking about. Right now it is all bundled in the box where the stat is. I thought that was odd unless that tube/wire isn't what i thought that it was or doesn't do what I thought it did. I thought that that tube/wire is what measured the temp and told the stat to kick on/off.

No?

 

[Gary RV_Wizard]

In a unit of this type, I think the thermostat is measuring the temp of the return air. It's not a wall t-stat, so the only access it has to "room temperature" is the room air the a/c is sucking in. It doesn't need a remote capillary tube - it is practically sitting in the middle of the air flow.  And the only communication it needs to the chiller unit is the wire that signals "need more cooling" (usually just one wire). I suspect the other wires in the 5 wire bundle are for the other functions on the selector switch.

Since the thermostat isn't digital, it is just a warmer/colder analog device. The differential between the target temperature and the room temp is proportional to the amount of rotation on the knob. Maybe a little or maybe a lot for a given amount of turn - it's a matter of trial and error. When you say the second click turning it off comes too soon, did you have the thermostat knob turned for max cold or just part way?

You can buy a whole new ceiling assembly for around $50-$60 bucks, so no need to fool around if you suspect it is not working right.

You can expect the chiller unit to drop the incoming air about 20 degrees. You get 70 degree output if the incoming air is 90, but if the output is 70 when the incoming room air is 80, something isn't working right.


By the way, Coleman Mach a/c's are a product of RV Products, which itself is a division of Airxcel. http://www.rvcomfort.com/rvp/

 

[Icemaker]

Yes that "wire" is in fact a sealed tube w/freon, or other gas/liquid, in it that expands/contracts w/temperature changes to cycle the compressor..
Without the directions I can't tell for sure it should be but in the control box is hard to fathom..the coil should be carefully unwound, read CAREFULLY as a kink or too sharp bend will ruin it, and the end pulled thru the control box or if it stands alone routed into the air flow of the return air..
Understand Seejay usually charges a pittance for his knowledge...I feel that in this instance it would be against my legal's council to admit in anyway that you should reimburse me other than that you NOT KILL OR INJURE YOURSELF OR OTHERS in any way by using this information..
That being said use your brain and  try to see a good routing, better if you had an old one in front  of you, for the cap tube.

George

 

[mayfair]

When you say the second click turning it off comes too soon, did you have the thermostat knob turned for max cold or just part way?

MAX cold setting
It would turn the compressor on and run it for about a minute, and then it would shut it off.