Truma AC blowing humid air?

[J Yoo]

My truma AC blows very humid air when its compressor cycles off. I can feel the humid air immediately after the compressor turns off and within 5 minutes, the humidity level inside increases to much higher than the outside. For example, the outside humidity was 45% and the inside humidity was 80% while the fan was running.  I have a thermometer that displays in/outdoor temperature and humidity levels. The AC runs as it should (cooling and dehumidifying) as long as the compressor is on. Is this normal? Anyone else have similar experience?

Hull 1264

[Rolind]

Unfortunately, this is normal for the Truma units and any other rv ac unit where the blower runs continuously as the compressor cycles on and off.  This is particularly a problem when the ambient humidity is high and the outside temp is close to the temp the ac is set to.  These conditions result in short compressor run times with long blower run times wo the compressor running. You can use the dehumidify setting on the Truma, accessed only with the remove control. This setting runs the compressor continuously and does a great job decreasing humidity at the cost of making the trailer very cold.  We usually just set the temp to much lower than we normally would to compensate for the increase humidity in the trailer, ie 65º at night. You can also purchase a small counter top dehumidifier as recently suggested in this great thread. 

 

[Jason Foster]

I’ve noticed the same thing and will be purchasing a small dehumidifier similar to what @Rolind posted above. 

[jd1923]

12 minutes ago, Jason Foster said:

I’ve noticed the same thing and will be purchasing a small dehumidifier similar to what @Rolind posted above. 

Jason, in your beautiful East Texas, buy a couple!

[Jason Foster]

Just now, jd1923 said:

Jason, in your beautiful East Texas, buy a couple!

Not a bad idea since the humidity here is often higher than the temperatures and they are almost always above 80. 

[jd1923]

4 minutes ago, Jason Foster said:

Not a bad idea since the humidity here is often higher than the temperatures and they are almost always above 80. 

When we lived in Georgetown, one of my son’s baseball coaches was from Beaumont, great coach!

He often said “nothing but swamp-@ss down there!”

I understand you’re a bit north/NW of there, up in the woods, but it’s 20% RH here today and it could be single digits.

We don’t have this on my wishlist, although if we were to ever make it to an OTT Rally, I’d buy one just for the trip!

[Jason Foster]

Just now, jd1923 said:

When we lived in Georgetown, one of my son’s baseball coaches was from Beaumont, great coach!

He often said “nothing but swamp-@ss down there!”

I understand you’re a bit north/NW of there, up in the woods, but it’s 20% RH here today and it could be single digits.

We don’t have this on my wishlist, although if we were to ever make it to an OTT Rally, I’d buy one just for the trip!

He is not wrong. If the trees were gone, this place would be a swamp. I would much prefer to live in the mountains and in a dryer climate, but this is where the job is.  I hate heat and despise humidity just a little more than I hate flat lands. 

[Geronimo John]

You may want to search the Air Stream site.  Their owners were the first to discuss the Houghton unit (Set 2 Same Problem).

This topic was addressed for these units on this thread plus several more:

 

[jd1923]

10 minutes ago, Jason Foster said:

but this is where the job is

We moved to Texas in 2006 for work, lived there 9 years. No better state of the Union than the Great state of Texas to work, period!

[Jason Foster]

1 minute ago, jd1923 said:

We moved to Texas in 2006 for work, lived there 9 years. No better state of the Union than the Great state of Texas to work, period!

There are a lot of good things about Texas and much money to be made. I wonder if it would have gone to pot like California if it had a temperate climate, some mountains and a bit more Ocean than the Gulf of America. 

[jd1923]

1 hour ago, Jason Foster said:

I wonder if it would have gone to pot

No f’n way.

Texas has pride in country, pride in their great state. The only thing Texas coulda done better was to stay the Lone Star state! If they had, we would have stayed there, for sure, but since the last few months of 2025, Made in America is getting great again…

Edited May 18 by jd1923

[Jason Foster]

1 hour ago, jd1923 said:

No f’n way.

Texas has pride in country, pride in their great state. The only thing Texas coulda done better was to stay the Lone Star state! If they had, we would have have stayed  

Still a great state tolive in though mountains and lots of snow would make it better. 
 

1 hour ago, jd1923 said:

 but since the last few months of 2025, Made in America is getting great again…

Agreed.  I just wish there would be a way to keep it going after these four years. 

[Ronbrink]

14 hours ago, Geronimo John said:

This topic was addressed for these units on this thread plus several more:

I recall you rectifying the issue with your Houghton by installing a relay, correct? Continuous fan run causing cabin humidity to rise seems to be a universal issue, even with the Truma. I replaced my DPll with a Dreiha Atmos 4.4 and use the Dry Mode when humidity begins to spike. Problem being, the cabin gets very cold if kept in that mode for too long and humidity level will eventually start to creep up again and thus, not a panacea. However, I recently learned of a viable solution with the Atmos to control the fan when the compressor shuts off, thereby significantly reducing said humidity concerns within. More importantly, only a minor alteration of the unit and no void of warranty. I look forward to reporting my findings. 

Edited May 18 by Ronbrink

[Geronimo John]

2 hours ago, Ronbrink said:

I recall you rectifying the issue with your Houghton by installing a relay, correct?

That is correct.  Two mods made the Houghton a great unit.  One to install a good quality ACR rated relay.  The other to abandon the Houghton thermistor in place and plug in a longer cabled one; then run the sensor bulb to a protect location.  The Relay Mod was not hard once one figures out all the wiring AND finds specific colored stranded copper wire to do so.  The Thermistor Replacement mod was super easy and super hard.  On the unit side, it is pull out the plug and plug in a new longer tailed one.  The hard was figuring out how to run the cable to a protected location in a manner that it is not a visual impairment (I.E.  UGLY.).   If an owner desires documentation for these mods kindly PM me.

Do you have more info on the mod for the Truma?  Did they resolve the short cycling issue as well?

One of these days the A/C MFG's will figure out that any premium unit must have the below attributes (In order of priority).

1. Compressor shut down when reaching set temperature.
2. Inverter Compressor like Danfos makes (Long life, extremely efficient, and super quiet.  Also eliminates need for soft start because it already is!)
3. Remote Thermistor/T-stat
4. Internal Drain System 
5. Nationwide Service Agreements
6. Reasonably price

The first one that does will dominate the market!  

GJ  

[Ronbrink]

1 hour ago, Geronimo John said:

Do you have more info on the mod for the Truma?  Did they resolve the short cycling issue as well?

I’m not aware of anyone commenting on mods to the Truma or short cycling issues, not to say there hasn’t been any discussion. Thanks for you response, very enlightening!

[Ronbrink]

On 5/16/2025 at 7:18 PM, J Yoo said:

My truma AC blows very humid air when its compressor cycles off. I can feel the humid air immediately after the compressor turns off and within 5 minutes, the humidity level inside increases to much higher than the outside. For example, the outside humidity was 45% and the inside humidity was 80% while the fan was running.  I have a thermometer that displays in/outdoor temperature and humidity levels. The AC runs as it should (cooling and dehumidifying) as long as the compressor is on. Is this normal? Anyone else have similar experience?

Hull 1264

In my post titled Drieha Atmos 4.4 Home Install/Ollie Modifications I recently provided comment on an easy remedy to the humidity issue with my unit, which may be applicable to the Truma Aventa, as well as other makes and models. 

Edited yesterday at 12:08 PM by Ronbrink