A/C unit

[eZAK]

Hello,

How fast should the main A/C unit cool the coach down?
We are new to High Country, So are not sure how well the ducted A/C works.

I turned it on "Cool Hi Auto" Set temp at 74* Stat read 84*.
Outside temp was 88*
In three hours it went down only 2*

Our previous coach, a 'Titanium', cooled down in about 15 min.

Both coaches are about the same size.

Thank You!

[DQDick]

The basic answer to that is no, it should do better. Do you have just the one AC?

[beeje]

It should cool down in 15 -30 min. Do you feel COLD air out of the vents?

[1retired06]

Agree, should cool down faster.

[eZAK]

It was cool when we picked it up and did our walk through (alone)

It does blow cool air out the vents, but not with much vigor.
I did check all vents as well as the returns. Some sloppy use of foil tape and
minor debris but nothing major.

I'm thinking of getting out a fish tape and pulling a rag through the duct work.

I also went on the roof and noticed slight frost on the coils.
Which may indicate low refrigerant or poor air flow over the coils.

At any rate I'll add this to the growing list of things that need to be fixed.

[Daryles]

Check to make sure your air ducts are not collapsed. You can do a search on PVC air duct modifications to find the thread on this.

[beeje]

They have also been many threads on the diffusers themselves sticking way up into the duct almost touching the top of the duct. Some found new diffusers that aren't as tall or cut the existing ones down

[luckeyd]

Change your fan speed to High. It will move lots more air.

[Sdgood1]

Originally Posted by luckeyd

Change your fan speed to High. It will move lots more air.

I’m with LuckeyD, I found that mine froze up when ran on auto, switched to high and no problem since

[glendodom]

Originally Posted by Sdgood1

I’m with LuckeyD, I found that mine froze up when ran on auto, switched to high and no problem since

By your note of reference to setting it to "High", I presume you mean "High" setting for the fan, correct? Thanks,

[cghsatx]

Originally Posted by glendodom

By your note of reference to setting it to "High", I presume you mean "High" setting for the fan, correct? Thanks,

These Dometic units are famous for cooling, then not cooling, having to be stopped and started etc, and have numerous posts. If I really want to be cool and not be surprised, I run them on high. At night, I turn off the bedroom unit, and get enough cool air from the LR unit running. The bedroom unit rattles the adjoining bathroom wall.

If anyone ever learns how to fix these, I sure hope they post in all caps.

[Mikelff]

Originally Posted by cghsatx

These Dometic units are famous for cooling, then not cooling, having to be stopped and started etc, and have numerous posts. If I really want to be cool and not be surprised, I run them on high. At night, I turn off the bedroom unit, and get enough cool air from the LR unit running. The bedroom unit rattles the adjoining bathroom wall.

If anyone ever learns how to fix these, I sure hope they post in all caps.

Well i hear all the new Montanas are now coming with Coleman units. That should tell you something. Most of the problems seem to be caused by the thermostat, but certainly not all. Knock on wood, Dometic has replaced one thermostat and seems to have taken care of my issue.. My dealer says they replace several a week! Just junk. A new unit should not be freezing up. It should operate as intended. DONT let it slide. Make them fix it.

[cghsatx]

Originally Posted by Mikelff

Well i hear all the new Montanas are now coming with Coleman units. That should tell you something. Most of the problems seem to be caused by the thermostat, but certainly not all. Knock on wood, Dometic has replaced one thermostat and seems to have taken care of my issue.. My dealer says they replace several a week! Just junk. A new unit should not be freezing up. It should operate as intended. DONT let it slide. Make them fix it.

I heard about the switch to Coleman. I had a Coleman in my 2006 Jayco and it never failed to run or cool. If I didn't owe so much on my 2019 3731, I'd trade it in. Its out of warranty now (bought in 2018) but I did get new thermostats, had it back to the dealer 3 times (for AC and other issues), had an independent RV look at it and nothing ever changed. I missed almost the entire first season I had it due to being it in and out of the shop. To avoid coming back to a 90 degree interior at the end of the day (in Texas), I just run them on high and hope for the best, and look forward to Fall, Winter and Spring, when its usually not 100

[Mikelff]

Originally Posted by cghsatx

I heard about the switch to Coleman. I had a Coleman in my 2006 Jayco and it never failed to run or cool. If I didn't owe so much on my 2019 3731, I'd trade it in. Its out of warranty now (bought in 2018) but I did get new thermostats, had it back to the dealer 3 times (for AC and other issues), had an independent RV look at it and nothing ever changed. I missed almost the entire first season I had it due to being it in and out of the shop. To avoid coming back to a 90 degree interior at the end of the day (in Texas), I just run them on high and hope for the best, and look forward to Fall, Winter and Spring, when its usually not 100

Hey, I get the 102 degree days. I'm in Ft. Worth. Wouldn't be any difference anyway. It would be on high 24/7 just to keep up! Lol

[MCJones]

I am going to guess you do have 2 units up there. IF not, the battle against heat has been lost We have the 295RL 2020. It takes awhile to cool down in the living area because of the high ceiling. Using the fan helps. The bed area is easy because you can just open the vents fore and aft and works great. Close the vents if you are trying to cool the living area too.

Good luck - mark

[SaraLouwho]

We are on our 7th Dometic in 6 years. All lasting between 6 months and a year, and all under warranty. I wonder if when I need another (under warranty in October) if they will authorize a Coleman?

[Mikelff]

Originally Posted by MCJones

I am going to guess you do have 2 units up there. IF not, the battle against heat has been lost We have the 295RL 2020. It takes awhile to cool down in the living area because of the high ceiling. Using the fan helps. The bed area is easy because you can just open the vents fore and aft and works great. Close the vents if you are trying to cool the living area too.

Good luck - mark

I have resorted to adding a 12k stand up portable AC unit(120V) that I vent out a side window. I run a separate extension cord to the main power stand. This helps quite a bit in the initial cool down and helps keep us nice and cool (75) in 100 degree days. The Dometic units just can’t handle that much heat. Another thing is to wrap my slide outs in radiant heat barrier. Just cut out where the windows are and use that on the inside. Secure it with parachute cord at the bottom. I look like a space ship but it’s amazing how much it keeps all that radiant heat out of my RV. Cooler months the portable is in the shed.

[RMcNeal]

Sorry SaraLouWho. I don't think they will. I asked the same question since we have been having serious problems with our Dometic Blizzard units. They say it's a different manufacturer and they won't authorize the switch. Even though they are now using Coleman instead of Dometic.

[Ren]

On our prior Montana HC, after the second year of ownership. I had to get my A/C buddy to braze in some ports on the dometic high and low side tubing to be able to refill the unit with refrigerant.

We had a coleman up front that was added when purchased and a dometic came with the unit in the rear. The coleman was cooling just fine 4 years later after we sold it.

So even though its a "Sealed" unit, lol.... they become....unsealed and leak.

[Brady’s Mom]

We found that some of our duct work had collapsed. I believe that over time this is a common occurrence. We had someone go through and prop up some of the duct work and saw an immediate improvement in the cold air flow.