We've had the trailer since new. It is about 32'. Air conditioning is original. It is the 15k model (Dometic?). I don't remember having problems in the past, but this year, the AC doesn't keep up as well as I would like.Trailer was in full sun. I had all the blinds down. Not running any appliances, the AC would keep the inside of the trailer about 10* lower than the outside temp. So, at 95* outside, it was about 85* inside.I have always heard that the air coming out the vents should be about 20* cooler than ambient indoor temp. I didn't check that, but we couldn't get anywhere near 20* cooler than outside temps.Is this to be expected, and I just have a bad memory of how it worked in prior years? Is there a way to add coolant to the unit? Would replacing the unit make a significant difference? If it is up to me, we are keeping the trailer, so I am ok spending some $.

filters clean? voltage drop coming into trlr? we use small floor fans tomove the air around. bring in unused slides. close connecting doors.

I have developed the habit of starting the a/C first thing after breakfast, set on low cool, but thermostat on max cold aka Temp all the way down,, it doesn't cycle the compressor , compressor and fans stay running, if I get chilly, I open a window or put on a warmer shirt,It gets cool and usually stays that way, Once an RV gets heat soaked, it will not cool down until the sun goes down

I have seen good roof airs replaced because the evaporator coil was filthy! You tube cleaning BRAND rv ac coils.

jjrbus wrote:I have seen good roof airs replaced because the evaporator coil was filthy! You tube cleaning BRAND rv ac coils.I would check this first. If you you still have the 02 model, and have never cleaned the coils, it likely needs to be done. You don't mention if you have a good electrical source, but if voltage is low, the AC can not function to the max.My 15K Dometic works very well in my 31' OAL FW, even in direct sun. I normally set it at 76 degrees, which it has no problem maintaining. At that temp, air blowing down, seems chilly, when hot outside.At 18 yrs old, your AC may not function like it did in earlier yrs. If that is the case, and you are happy with your trailer, I'd replace it with a new 15K unit.Jerry

So why don't we check the in and out differential temps and resolve the issue of whether the ac is performing its end?

How cold should the air conditioning get the RV?

wa8yxm
Explorer III
Aug 11, 2020
One thing many do not do often enough is go topside.
First Pop the cover off the A/C
Then pop the inner cover off the CONDENSER (Outside coils)
Isnpect. they need cleaning often 2 or 3 times a year.

Also clean the inside filters and inspect

Now put it all back together and fire it up. measure air temp at inlet and outlet. should be minimum 20 degrees difference in most cases. Actual difference will vary with outside temp and humidity.

If you measure outside air temp and condeser outlet temp and humidity then there is a book that has chart after chart that says "Working/Not"

Finally. While up on the roof. MOP IT. Just like a kitchen floor

Spic & Span. Bucket.. Mop or long handled car wash brush. Water
Then hose it off
time2roll
Nomad
Aug 11, 2020
Check the plenum divider in the lower section that it is well placed and sealed to separate air in from air out. Access by removing the interior trim.

Get a couple a/c thermometer for next trip. Look for ice buildup on the evaporator when testing. Again remove the interior trim. If you see ice check that the freeze sensor is right in the ice. Could have been additional humidity on the last trip.
dougrainer
Nomad
Aug 11, 2020
1. 32 RV. A 15k will NOT cool the RV adequately in temps over 85 degrees. PERIOD. You need 2 AC units in RV's over 27 foot. Especially since Slide Outs are almost standard in Trailers. Do you have a slide out?
2. IR temp guns are NEVER used to determine Air temp in a AC system or a Refer system. You must use a digital thermometer to determine air temps.
3. The ONLY correct test on the performance of a AC unit after all variables have been verified(coils clean/filter clean/divider gasket) is a temp corrected AMP draw of the compressor.
4. RV AC units only hold about 1 lb of coolant. So, if you do have a leak, it will either cool or not. Not partially, as the coolant will have leaked out enough to not work at all. Doug
MFL
Nomad II
Aug 11, 2020
cavie wrote:
Get a thermo inferred temp gun from Harbor Fright.

I use a thermometer to measure air temps, rather than my IR gun. It is much more accurate, unless checking temp on surface.

Jerry
cavie
Explorer
Aug 11, 2020
Your question is like asking "How long is a piece of rope. Too many variables. Parked in the sun/shade? Temp outside??? Last time you cleaned the coils on the roof?. last time you cleaned the filter inside? Get a thermo inferred temp gun from Harbor Fright. You should get 18/20 degrees between supply air and return air inside. if you get that your good to go.
Dave_H_M
Explorer II
Aug 11, 2020
So why don't we check the in and out differential temps and resolve the issue of whether the ac is performing its end?
MFL
Nomad II
Aug 11, 2020
jjrbus wrote:
I have seen good roof airs replaced because the evaporator coil was filthy! You tube cleaning BRAND rv ac coils.

I would check this first. If you you still have the 02 model, and have never cleaned the coils, it likely needs to be done. You don't mention if you have a good electrical source, but if voltage is low, the AC can not function to the max.

My 15K Dometic works very well in my 31' OAL FW, even in direct sun. I normally set it at 76 degrees, which it has no problem maintaining. At that temp, air blowing down, seems chilly, when hot outside.

At 18 yrs old, your AC may not function like it did in earlier yrs. If that is the case, and you are happy with your trailer, I'd replace it with a new 15K unit.

Jerry
jjrbus
Explorer
Aug 11, 2020
I have seen good roof airs replaced because the evaporator coil was filthy! You tube cleaning BRAND rv ac coils.
MrWizard
Moderator
Aug 11, 2020
I have developed the habit of starting the a/C first thing after breakfast, set on low cool, but thermostat on max cold aka Temp all the way down,, it doesn't cycle the compressor , compressor and fans stay running, if I get chilly, I open a window or put on a warmer shirt,
It gets cool and usually stays that way,
Once an RV gets heat soaked, it will not cool down until the sun goes down
rk911
Explorer
Aug 11, 2020
filters clean? voltage drop coming into trlr? we use small floor fans to
move the air around. bring in unused slides. close connecting doors.

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