Rear air conditioner low fan setting

[Smitty8934]

I've had this problem since day one with the factory installed rear air conditioner. When running the fan low and the system set on cool, the fan is suppose to run continuously with the compressor cycling on and off as needed. This works the same with the fan on high. What happens with mine is again with the fan set on low and in the cooling mode once the correct temperature is reached the whole system shuts off and does not come back on. If I run it in the same mode with the fan set on high, it cycles properly. When using the "auto" mode the entire system cycles on and off including the fan which is correct. I've had it in twice for this and now they say it could be a power problem with the pedestal. Funny it does it at every campground we've been at. They are hunting in the dark for that excuse. Anyone out there having this similar problem with a solution to fix it?

[kdeiss]

My guess would a problem circuit board in the Electronic Controll Box located in the AC Unit.

[dieselguy]

We never run the fan on low in the COOL mode as it tends to make the unit ice up due to lack of airflow over the coils. Many of us run the A/C on high or at least medium and regulate the temp at the thermostat. You may be experiencing icing instead of cycling at the set temp.

[DQDick]

I run mine on Auto, but would never run it on low. Like Diesel Guy states, running on low is a good way to freeze them up.

[Smitty8934]

Let me re-explain. When on low-cool it only runs for a few minutes when reaching the temp it shuts off whereas the fan should continue to run. It has not even come close to freezing up.

[Eagleback]

There is a problem with the board on the unit or your thermostat. I would try and replace the stat first. But its almost like 2 wires are connected to the same terminal, Might want to look at that also.

[Bama Camper]

I've had the same problem, just discovered it a different way.

There is a freeze protection sensor in the AC. If the sensor senses a freeze up of the coil, it shuts down the AC. That's the reason it will not come back on. It is locked out because of the freeze protection circuit. The reason it does it only on low fan is that you are not moving enough air across the coil to keep it from freezing. In high fan you do, and it doesn't freeze up, therefor it cycles properly.

In my case I discovered this because of a lot of different problems with the AC (I won't into those to keep this short!), but that was one of them.

Your AC could be freezing up for a lot of different reasons (low air flow because of restricted ducts, dirty filters, low freon, etc.), BUT the most common problem in our ACs that causes freeze-ups is an air dam that has fallen down inside the unit. Dometic claims it happens when the ACs are installed and it's not their fault, but it doesn't matter, it's a common problem with their units. The dam separates the incoming air chamber from the exhaust air chamber. You'll have to (or get your service tech to) remove the face of the unit and examine the sheet metal and the chambers. You'll likely find it loose. In mine, the tech shot a couple of sheet metal screws into it to hold it in place. Also, use plenty of duct tape to seal the remaining cracks.

You can test for this by running on low fan until it shuts off. Then, remove the faceplate and look up inside with a flashlight to see if there is ice on the coil.

Good luck!

[kdeiss]

I have two Dometic Brisk Air II AC Units with freezing up issues.When I checked the bedroom unit the Freeze sensor probe was not installed just laying next to the evaporator coil the main unit the probe was mounted in the center of the evaporator coil.They should be mounted on the left side ( Curb Side)one inch from the bottom of the evaporator coil.I had premature shut off due to freezeing on both high fan speed

[kdeiss]

quote:Originally posted by kdeiss

I have two Dometic Brisk Air II AC Units with freezing up issues.When I checked the bedroom unit the Freeze sensor probe was not installed just laying next to the evaporator coil the main unit the probe was mounted in the center of the evaporator coil.They should be mounted on the left side ( Curb Side)one inch from the bottom of the evaporator coil.I had premature shut off due to freezeing on both high and low fan speed.I had to turn unit thermostat off then back on to restart also had to correct some Air Dam issues as mentioned.Correct mounting of Freeze Sensor and Air Dam is the installers responsible

[Smitty8934]

quote:Originally posted by Bama Camper

I've had the same problem, just discovered it a different way.

There is a freeze protection sensor in the AC. If the sensor senses a freeze up of the coil, it shuts down the AC. That's the reason it will not come back on. It is locked out because of the freeze protection circuit. The reason it does it only on low fan is that you are not moving enough air across the coil to keep it from freezing. In high fan you do, and it doesn't freeze up, therefor it cycles properly.

In my case I discovered this because of a lot of different problems with the AC (I won't into those to keep this short!), but that was one of them.

Your AC could be freezing up for a lot of different reasons (low air flow because of restricted ducts, dirty filters, low freon, etc.), BUT the most common problem in our ACs that causes freeze-ups is an air dam that has fallen down inside the unit. Dometic claims it happens when the ACs are installed and it's not their fault, but it doesn't matter, it's a common problem with their units. The dam separates the incoming air chamber from the exhaust air chamber. You'll have to (or get your service tech to) remove the face of the unit and examine the sheet metal and the chambers. You'll likely find it loose. In mine, the tech shot a couple of sheet metal screws into it to hold it in place. Also, use plenty of duct tape to seal the remaining cracks.

You can test for this by running on low fan until it shuts off. Then, remove the faceplate and look up inside with a flashlight to see if there is ice on the coil.

Good luck!

[Smitty8934]

quote:Originally posted by Smitty8934

I've had this problem since day one with the factory installed rear air conditioner. When running the fan low and the system set on cool, the fan is suppose to run continuously with the compressor cycling on and off as needed. This works the same with the fan on high. What happens with mine is again with the fan set on low and in the cooling mode once the correct temperature is reached the whole system shuts off and does not come back on. If I run it in the same mode with the fan set on high, it cycles properly. When using the "auto" mode the entire system cycles on and off including the fan which is correct. I've had it in twice for this and now they say it could be a power problem with the pedestal. Funny it does it at every campground we've been at. They are hunting in the dark for that excuse. Anyone out there having this similar problem with a solution to fix it?

[Smitty8934]

quote:Originally posted by Smitty8934

I've had this problem since day one with the factory installed rear air conditioner. When running the fan low and the system set on cool, the fan is suppose to run continuously with the compressor cycling on and off as needed. This works the same with the fan on high. What happens with mine is again with the fan set on low and in the cooling mode once the correct temperature is reached the whole system shuts off and does not come back on. If I run it in the same mode with the fan set on high, it cycles properly. When using the "auto" mode the entire system cycles on and off including the fan which is correct. I've had it in twice for this and now they say it could be a power problem with the pedestal. Funny it does it at every campground we've been at. They are hunting in the dark for that excuse. Anyone out there having this similar problem with a solution to fix it?

[Smitty8934]

quote:Originally posted by Bama Camper

I've had the same problem, just discovered it a different way.

There is a freeze protection sensor in the AC. If the sensor senses a freeze up of the coil, it shuts down the AC. That's the reason it will not come back on. It is locked out because of the freeze protection circuit. The reason it does it only on low fan is that you are not moving enough air across the coil to keep it from freezing. In high fan you do, and it doesn't freeze up, therefor it cycles properly.

In my case I discovered this because of a lot of different problems with the AC (I won't into those to keep this short!), but that was one of

Your AC could be freezing up for a lot of different reasons (low air flow because of restricted ducts, dirty filters, low freon, etc.), BUT the most common problem in our ACs that causes freeze-ups is an air dam that has fallen down inside the unit. Dometic claims it happens when the ACs are installed and it's not their fault, but it doesn't matter, it's a common problem with their units. The dam separates the incoming air chamber from the exhaust air chamber. You'll have to (or get your service tech to) remove the face of the unit and examine the sheet metal and the chambers. You'll likely find it loose. In mine, the tech shot a couple of sheet metal screws into it to hold it in place. Also, use plenty of duct tape to seal the remaining cracks.

You can test for this by running on low fan until it shuts off. Then, remove the faceplate and look up inside with a flashlight to see if there is ice on the coil.

Good luck!

[Smitty8934]

I do not have access to the air conditioner units inside my fifth wheel as it only has air returns that run on the perimeter of the ceiling, there's no grill in the middle of the ceiling. Access would only be from the roof. I think they call this a whisper system or something like that. I just got it back from the service dept and now I know how they tested it. They only ran the fan without the cooler on. I explained it to them but evidently they didn't understand what I was saying. It's too cold now in upper Michigan to test properly so they've noted on my file what's happening and I can bring it in this spring once it's warmed up again. Guess I'll see what happens. Thanks all.