Coleman 4803A876 low fan and low cool do not work but high fan and high cool work

The heat will normally use a low speed on the fan, & the AC along with the fan switch on the thermostat will use the high speed. The thermostat turns that high speed on when there is a call for cooling & is the same switch if you were to manually turn the fan from auto to on. Try turning the fan on @ the thermostat. If it works, then replace your thermostat. If it doesn't, it could be a bad fan speed, a bad fan relay on a control board or external relay, or a loose or broken green thermostat wire.

Please describe your controls. Does it not have low fan, high fan, low cool, high cool on the dial at ceiling? If yes, low cool or high cool setting should shut it down when temperature is reached via thermostat dial.

If this is a 'new' unit I would contact Coleman and explain the problem you are having. I would think that they would have to honor the warranty on the unit. That is, if a AC company installed the unit. However, from your explanation of the problem it appears that you might of installed the unit yourself in which case - 'they' (Coleman) might decide to 'not' honor it. A gray area for sure. Still, I would try and see if they would help you.
In the case they won't - I would get ahold of a AC Tech and have him/her troubleshoot the unit before I started removing and adding electrical components.
From what you've said - I wouldn't think you have anything seriously wrong - you just need someone to figure out why it's not working as it should.
My best guess - is that it's a simple electrical problem that can be solved with one service call and for a minimum cost.
Worst case - might be a major component (i.e. compressor) that is bad (which is not likely) but in any event with the AC Tech's help - Coleman would probably honor the warranty on the compressor and you would only be out the labor for the AC Tech to install it. Note: some warranties will even cover the labor to put it in.
Bottom line - I would try to get Coleman to help me directly or with the help of a AC Tech, and in the event they won't - I would trust the AC tech to find the problem and repair it.

Are there any filters? If they are clogged the unit will not work properly and the temp will not drop as much as it should as it cannot absorb the air in the trailer or room.

jbrown - Hot air rises, Cold air falls. If you have ceiling fans upstairs, turn them on to run counterclockwise at highest speed you can stand. Make sure all the windows are closed upstairs. The ceiling fans will help to keep the cool air upstairs and pull some from downstairs.

If you don't have ceiling fans, invest in a box type fan that you can place at the head of the stairs (that's the top of the stairs) run it on HIGH and it will act like an exhaust fan, by pulling cool air upstairs. It may take a while, but it will help cool the upstairs to some degree.

Hope this helped you. Please let me know. Thanks.

Hate to have to ask you so many questions but something isn't adding up here. Original post said it cycles off and will not come on for hours, yet, last comment said if fan on high, compressor kicks in and out every few minutes, so I think I'm getting a little mixed up, sorry. So i need to ask a few more questions. How old is the unit roughly? Has it been working good up until this happened? Have you tried dropping the ceiling assembly down by removing the 4 bolts holding it to roof unit, and looking on the forced air side of the ceiling assembly to make sure there is no obstructions to duct work such as rubber roof material hanging down etc, that would block any flow to ducts. Do you have all, or most of your ducts open to allow cool air to distribute itself properly? If you have done all this work yourself, have you tried by-passing the thermostat and connecting wires at control box, to see if unit stays running that way? If you didn't do the work, don't guess, please.

It may also be an obstruction in the ducting. When the forced air is restricted somewhere, it will freeze the coils, and compressor shuts down, until frost is gone, then starts back up and will repeat that all day. I'm thinking that the restriction doesn't affect it as much when fan on low. I'm going to assume this is a ducted system. If I'm right, first, make sure all ceiling ducts are open and if not, open them all up full and see if that changes anything. If it does, you've solved the problem. If it doesn't, shut unit down, remove air filter at ceiling, and then restart unit on high fan. Where the divider is between return air and forced air, carefully look up there with a flashlight and see, as well as feel, very carefully around the edges of that divider for cool air coming in to mix with return/warm air. If you feel quite a bit of cool getting through, shut the unit off again, and use foil tape to seal it up well, then retry it. If not a noticeable amount leaking through, remove the rest of the screws holding that ceiling assembly up, and lower it down as far as you can. Now look at the ducts that go into the ceiling for forced air and make sure they are wide open and no rubber roof hanging in them, or tape or anything else that may restrict flow at all. That is often where you will find that the rectangular opening has been restricted, and will cause that problem as well. If there's rubber roof , or similar in the way, carefully cut it out of there and apply foil tape over anything loose or even gaps into ceiling or roof area, and anywhere else. You want all the forced air going into a wide open duct and nowhere else. Hope that helps. Only other thing you may want to confirm first as well, would be that you do have 115-120 vac, hydro required, going to it. Only other test after that would be an amp draw test, that would require a clamp on amp-meter. My guess is that it's an obstruction in forced side. Keep me posted will ya?

Sounds like you have either a bad fan motor or a bad fan motor capacitor. When you turn the unit on with the fan not working, the compressor (the humming noise) runs and gets real hot real quick resulting in the compressor cutting off ( the nothing after) on it's inside high temp switch. This is what the compressor is designed to do so that when this happens, it does not burn the compressor out. Replace you fan capacitor, give the compressor an hour to cool, then try it. In most cases and if I'm correct, the unit will run just like you want it to. Good luck.
Please rate solution

R = HOT 12V
W= WHT- GND
Y = YELLOW / POSSIBLE THERMOSTAT
G= GRND FOR THERMOSTAT
f = FAN
F=FAN
aSSUMING THIS IS A TWLVE VOLT SYTEM- The two f's Would be fan control intake and exhaust - fan direction
White is always ground and so is green.. green is more of a static ground where white is a load grnd.
Red is always hot. in low voltage

I hope this helped. No instructions in kit?

the fan motor bearings need lub....the shaft has a tiny access hole to put some oil into. because the fan shaft is slowing down, it is putting more strain on the voltage current, and eventually the internal breaker shuts down the ac........plus your condenser is not getting enough air accross it, compressor heats up, and it too will shut the unit down......older units have to be oiled every year, and eventually it too will fail, and a new blower motor assembly is needed or replace the ac unit.....blower motor units are around $130....now you install it or pay to have it done at around another $150 labor,,,,,try yourself, if it fails then call the tech........let me know [email protected]