Dometic AC Will Only Run On High Fan Speed

[gintera563]

Hello Everyone! For about the last two years the AC in our 2014 Puma travel trailer will only operate on high fan speed. As long as we start the fan on high then switch over to cool the AC run perfect and cools the camper as it should. If we switch it to low or auto, we can hear a click in the control board (above the filter inside the camper) but the fan will shut off. If we try to start it on low or auto, we get the same click and no start. If we wait a few seconds, we can hear the compressor humming but no fan. I have tried switching out the thermostat but that didn't help. I'm wondering where to go from here... Control board, fan motor, or something else?? Any help would be great!

 

[Rene T]

Welcome to the forum. Just a little tip. You only need to post your question in one section. If the forum staff feels that your post would get better coverage or exposure in another section, they'll move it.

 

[gintera563]

That is very helpful to know, thanks!

 

[56safari]

byrantrv.com has a diagnostic service manual for the Duotherm AC units that will help if you have that type AC unit.

Fan speed is typically controlled by a resistor or through a control  board.  It is also possible that the motor has separate windings for each speed,  In any case you'll need the manufacturer and model number to find the correct wiring diagram or diagnostic manual.

Good luck!

 

[John From Detroit]

120 volt fans typically use the multi-winding method.

Possible issues
Bad relay (The clicker)
Bad wire/connection
Bad low speed winding


Suggestion:  Many people report issues with A/C icing up when run on LOW.. Do not use LOW. Use High, that's what I do. Even though low works (I do admit to using LOW fan from time to time.. Just fan not cool)

 

[gintera563]

I have now tried a new thermostat, control board, and checked the wire connections. I'm guessing the next step is a new fan??

 

[Willandgiselarv]

I have the same issue with my rear ac...
Haven't gotten on roof to inspect most likely will order a new fan motor with the capacitor..
Low speed used to work but was clicking badly, now it's completely dead and only high speed works.

 

[gintera563]

I think I'm going to try a new fan motor next...

 

[Willandgiselarv]

Let me know which part# of fan assembly you ordered and if it fixed the problem.
I haven?t gotten around to fix it because the a/c works and the weather permits me to wait.
Thanks

 

[fayskelley]

My Dometic just started acting up. How was this resolved for you all who worked on this? Thx.

I’m wondering how long it will run just using high.

 

[Henry J Fate]

This is an old thread.

If you have a dual speed fan (Hi and Low) and only one is working, it should not affect the usefulness or life expectancy of the working speed.

If you would like to troubleshoot to find the problem, it should start on the roof at the ac unit where a qualified person can identify the fan motor speed wires, measure the motor with a multimeter and decide whether or not to test the non working speed by applying power to it. This will determine if the non working speed of the motor is good or bad. If it's good, the control circuit will need to be tested. This includes the thermostat, control board and the wiring associated with those. If the motor is bad, motor replacement is needed.

 

[fayskelley]

This is an old thread.

If you have a dual speed fan (Hi and Low) and only one is working, it should not affect the usefulness or life expectancy of the working speed.

If you would like to troubleshoot to find the problem, it should start on the roof at the ac unit where a qualified person can identify the fan motor speed wires, measure the motor with a multimeter and decide whether or not to test the non working speed by applying power to it. This will determine if the non working speed of the motor is good or bad. If it's good, the control circuit will need to be tested. This includes the thermostat, control board and the wiring associated with those. If the motor is bad, motor replacement is needed.

Thank you so much !

 

[Gary RV_Wizard]

The thermostat may not be compatible with the a/c control. This sort of fan problem is common is a residential thermostat replaces the original, or when an old analog rv thermostat is replaced with a digital.

You said your Dometic is "acting up". Is it exactly the fan speed issue in the old topic or is there more to it? What thermostat do you have and what model or Dometic a/c. One a/c or multiple zones?

 

[fayskelley]

Thx
The Dometic AC and wall thermostat worked fine for 3 years. Original installation of new. I have not changed anything.

 

[Kies277]

I just repaired my A/C in my wife's mini van and in my research I found that if the rear A/C only works on high, that is the sign of a bad resistor. I'm not sure if these RV units have a resistor or not, but might be worth a Google search.

 

[evanontheroad]

Hello Everyone! For about the last two years the AC in our 2014 Puma travel trailer will only operate on high fan speed. As long as we start the fan on high then switch over to cool the AC run perfect and cools the camper as it should. If we switch it to low or auto, we can hear a click in the control board (above the filter inside the camper) but the fan will shut off. If we try to start it on low or auto, we get the same click and no start. If we wait a few seconds, we can hear the compressor humming but no fan. I have tried switching out the thermostat but that didn't help. I'm wondering where to go from here... Control board, fan motor, or something else?? Any help would be great!

I have been experiencing this same problem for a month now, the issue was much more dangerous than I expected, but the solution was simple. My fan would work on high, but not on low. (I could bypass this problem by turning the fan on high and then switch it to low, however the problem persisted.) Another issue that I was experiencing was my internal breaker would trip inconsistently.

If you are experiencing this problem check your trailer/RV's electrical plug, it may need to be replaced. If the plug is hot to the touch after being plugged in, if it is bulged on the sides, or if you notice oxidation on a prong you will need to replace it ASAP. A replacement plug is under twenty dollars and the job is relatively simple. (I have a 30amp plug, green goes to the top, white wire goes to the right, and black wire goes to the left...the replacement plug should have colored screws to help make the work as simple as possible.)

The worker at the park who told me of this solution didn't change his plug in time and it caused a fire at the pedestal, so please take a second to examine your plug.

All the best,
Evan

 

[Tulecreeper]

I have been experiencing this same problem for a month now, the issue was much more dangerous than I expected, but the solution was simple. My fan would work on high, but not on low. (I could bypass this problem by turning the fan on high and then switch it to low, however the problem persisted.) Another issue that I was experiencing was my internal breaker would trip inconsistently.

If you are experiencing this problem check your trailer/RV's electrical plug, it may need to be replaced. If the plug is hot to the touch after being plugged in, if it is bulged on the sides, or if you notice oxidation on a prong you will need to replace it ASAP. A replacement plug is under twenty dollars and the job is relatively simple. (I have a 30amp plug, green goes to the top, white wire goes to the right, and black wire goes to the left...the replacement plug should have colored screws to help make the work as simple as possible.)

The worker at the park who told me of this solution didn't change his plug in time and it caused a fire at the pedestal, so please take a second to examine your plug.

All the best,
Evan

The person you are replying to hasn't been on this thread for going on 6 years.

 

[evanontheroad]

The person you are replying to hasn't been on this thread for going on 6 years.

Understood, but when I did a Google search on the issue I was experiencing this thread popped up. My intent isn't to necessarily to help the original poster but anyone else experiencing the same problem that is brought here.