Forum Discussion

dpgllg's avatar
dpgllg
Explorer
Jul 13, 2019

Dometic AC potential issues

SEE UPDATE ON PAGE 2

My Dometic AC froze up while camping last weekend. I would let it thaw and it seemed to work for awhile and then freeze up again.

When we got it to the storage yard I took the inside cover off and discovered that the Freeze control sensor was not connected. I ordered a replacement and brought the RV home so I could plug it in. I replaced the sensor and the air is moving but it does not seem that cold to me.

I made sure that the baffle between the warm and cold air was in place and not leaking. The AC is putting water out across my roof as expected.

My brother looked at it and he said "maybe" the compressor is going bad. I have no clue how to tell if the compressor is having issues.

This AC is 25 months old so it shouldn't be worn out. I have already talked to Dometic and they are going to extend my warranty to get it repaired or replaced but I have to wait for an appointment anywhere between 4 to 6 weeks to get into the shop.

While I'm waiting is there anything else I can do to troubleshoot the AC? I'm going to let it run awhile to make sure that the freeze up is resolved. If it does freeze up again then it's possible that the Freon is low. Since it is a sealed unit then a replacement would be required.

Thanks in advance for your assistance!

Dave
  • beemerphile1's avatar
    beemerphile1
    Explorer
    Jul 13, 2019
    Put a thermometer in the return air and note the temperature. Then put the thermometer in the discharge air flow and note the temperature. What is the difference? If the discharge is 18 or more degrees colder, everything is good.
  • dougrainer's avatar
    dougrainer
    Nomad
    Jul 13, 2019
    1. The freeze Sensor not connected. WHY would you install a new one? Why not just install the old one?
    2. They are sealed systems. IF you had a leaker, then ALL the coolant would have been gone by now. They only hold a 16 ozs of coolant.
    3. Water Coming OFF the roof indicates the Unit is doing its job.
    4. Your brother and you have no way to tell if the compressor is "going" bad:B FYI, your compressor is not going bad.
    5. How hot is it and how big is your RV? Doug
  • dpgllg's avatar
    dpgllg
    Explorer
    Jul 13, 2019
    dougrainer wrote:
    1. The freeze Sensor not connected. WHY would you install a new one? Why not just install the old one?
    2. They are sealed systems. IF you had a leaker, then ALL the coolant would have been gone by now. They only hold a 16 ozs of coolant.
    3. Water Coming OFF the roof indicates the Unit is doing its job.
    4. Your brother and you have no way to tell if the compressor is "going" bad:B FYI, your compressor is not going bad.
    5. How hot is it and how big is your RV? Doug


    OP here,

    The end of the sensor did not have the flat blade attached so it broke off or whatever. To be safe it wasn't an expensive part so I replaced it.

    I stated that I had no clue about the compressor. Was hoping for a little feedback if there was any simple way to determine any issue with it.

    It was in the mid 70's now 80 at noon and the AC has not shut off at all.

    It is a 32 foot 5th wheel and the AC is a 15,000 BTU unit.
  • belairbrian's avatar
    belairbrian
    Explorer
    Jul 13, 2019
    Two solid pieces of advice already posted.
    1) check the differential temp - That should tell you if the compressor is working properly.
    Run A/C fan on high- At one time Dometic had a service bulletin about running with low fan causing evaporator coil icing in high humidity.

    Make sure the fan switch is in Auto. If the fan is in ON, it will seem like the system is running all the time.
  • dougrainer's avatar
    dougrainer
    Nomad
    Jul 14, 2019
    dpgllg wrote:
    dougrainer wrote:
    1. The freeze Sensor not connected. WHY would you install a new one? Why not just install the old one?
    2. They are sealed systems. IF you had a leaker, then ALL the coolant would have been gone by now. They only hold a 16 ozs of coolant.
    3. Water Coming OFF the roof indicates the Unit is doing its job.
    4. Your brother and you have no way to tell if the compressor is "going" bad:B FYI, your compressor is not going bad.
    5. How hot is it and how big is your RV? Doug


    OP here,

    The end of the sensor did not have the flat blade attached so it broke off or whatever. To be safe it wasn't an expensive part so I replaced it.

    I stated that I had no clue about the compressor. Was hoping for a little feedback if there was any simple way to determine any issue with it.

    It was in the mid 70's now 80 at noon and the AC has not shut off at all.

    It is a 32 foot 5th wheel and the AC is a 15,000 BTU unit.


    A 15k AC in a 32 foot RV will NOT cool the RV. Especially if you have slide out/s. Period. The max size for a ducted 15k is about 27 feet. Don't listen to responders that state they have a over 27 foot that does cool with 1 AC. I am giving you 40 years experience with RV's and sizing of Roof AC units. You need to have a operational check of that AC unit. You need
    1. The compressor amp draw at ambient correct temp
    2. The Temp Differential between the closest cold air outlet and the return air filter. The temp Diff will be 19 to 22 degrees. IE -- 82 hot in 62 cold out would be very good. Doug
  • jkwilson's avatar
    jkwilson
    Explorer II
    Jul 14, 2019
    dougrainer wrote:
    dpgllg wrote:
    dougrainer wrote:
    1. The freeze Sensor not connected. WHY would you install a new one? Why not just install the old one?
    2. They are sealed systems. IF you had a leaker, then ALL the coolant would have been gone by now. They only hold a 16 ozs of coolant.
    3. Water Coming OFF the roof indicates the Unit is doing its job.
    4. Your brother and you have no way to tell if the compressor is "going" bad:B FYI, your compressor is not going bad.
    5. How hot is it and how big is your RV? Doug


    OP here,

    The end of the sensor did not have the flat blade attached so it broke off or whatever. To be safe it wasn't an expensive part so I replaced it.

    I stated that I had no clue about the compressor. Was hoping for a little feedback if there was any simple way to determine any issue with it.

    It was in the mid 70's now 80 at noon and the AC has not shut off at all.

    It is a 32 foot 5th wheel and the AC is a 15,000 BTU unit.


    A 15k AC in a 32 foot RV will NOT cool the RV. Especially if you have slide out/s. Period. The max size for a ducted 15k is about 27 feet. Don't listen to responders that state they have a over 27 foot that does cool with 1 AC. I am giving you 40 years experience with RV's and sizing of Roof AC units. You need to have a operational check of that AC unit. You need
    1. The compressor amp draw at ambient correct temp
    2. The Temp Differential between the closest cold air outlet and the return air filter. The temp Diff will be 19 to 22 degrees. IE -- 82 hot in 62 cold out would be very good. Doug


    My Atwood did a fine job in August of 2017 when we could only get a 30A site for the eclipse. 95, humid as heck and no shade in the middle of the day. It worked hard, but kept it in the 70s.
  • dpgllg's avatar
    dpgllg
    Explorer
    Jul 14, 2019
    "A 15k AC in a 32 foot RV will NOT cool the RV."

    OP here,

    Do I need to add a 2nd AC? I thought you could only run one AC at a time? I do have 50 amp service. I am also prewired for a 2nd ac.

    Is there a bigger more powerful ac than a 15,000 BTU AC?

    Dave
  • dougrainer's avatar
    dougrainer
    Nomad
    Jul 15, 2019
    dpgllg wrote:
    "A 15k AC in a 32 foot RV will NOT cool the RV."

    OP here,

    Do I need to add a 2nd AC? I thought you could only run one AC at a time? I do have 50 amp service. I am also prewired for a 2nd ac.

    Is there a bigger more powerful ac than a 15,000 BTU AC?

    Dave


    If you have 50 amp service, then add the 2nd unit. Yes, they do build larger than 15k, but those are newer entry Brand units that do not have a track record. Most of the other brands ( NOT Dometic and RVP/Coleman), that entered the RV market in the past 15 years are no longer around. I would NEVER install any AC unless it was a Dometic or RVP. If the other brands go away, you cannot get parts or help. I believe the larger than 15k is around 16.5 or 17k. Still not enough extra BTU's to do the job you need done. You still need your existing AC checked out to make sure it is at spec and INSTALLED correctly. Doug
  • dpgllg's avatar
    dpgllg
    Explorer
    Jul 15, 2019
    OP here,

    I started looking at getting a 2nd AC unit installed but I need to know what all parts that I would need. I want a Dometic 15,000 BTU Brisk Air II unit with black / dark shroud. This would be a ducted system with thermostat. My 5th wheel is prewired including the thermostat wire.

    I have found the upper roof top units and I know that I need a ceiling assembly for inside and a thermostat. I think that there is a control box as well but I have no clue what actual part number that is.

    Is there anyplace online that lists all of the required components? The local RV shops are all booked for the next 6 weeks so I want to at least know what is required and the cost of the parts before I take it in.

    Thanks!

    Dave

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,188 PostsLatest Activity: Jan 17, 2025