ac froze up when fan on low speed.

M GO BLUE wrote:
Don't want an answer then don't ask in a public forum.

Don't get all upset......but I didn't really find your response helpful at all. You didn't really answer anything. You stated something as a fact that quite obviously I didn't know about, hence the questions which were: Should this be an issue? Anyone else have this happen?.
Now which question exactly did you answer? Neither.

ksg5000 wrote:
For what it's worth .. my Class C is over 20 years old ... has wall thermostat that controls both heater and AC .. and the Coleman AC unit did not come with freezer sensor.

That does not mean it was never offered or installed. Years ago, a LOT of OEM's did not install the freeze sensor because the production workers did not know what they were. They threw them away. Doug

Jerallen wrote:
Thanks for the replies- all helpful with exception of that last one.

Don't want an answer then don't ask in a public forum...

Wouldn't it be easiest to check and see of the freeze sensor fell out of the coils like SM suggested.

I stuck mine back in there and it worked fine on low fan. :h

For what it's worth .. my Class C is over 20 years old ... has wall thermostat that controls both heater and AC .. and the Coleman AC unit did not come with freezer sensor.

MrWizard wrote:
I will not belabor to argue the point further, but no....
20 years ago a t stat on the wall was the heater, and did not control the a/c

But, the point is, there are VERY FEW 20 year old RV's(towables) still in service. MOST of the complaints and calls for help on these forums are RV's no more than 15 years old. About 20 years ago, is when they started putting wall tstats in motorhomes. Doug

When the defrost cycle activates on my Dometic Penguin on low fan speed, it interrupts the compressor and speeds up fan temporarily. While it is better than the unit freezing up, to me it is less desirable than not having it happen at all. I have never entered the defrost cycle on medium or high fan speed.

I will not belabor to argue the point further, but no....
20 years ago a t stat on the wall was the heater, and did not control the a/c

MrWizard wrote:

Very few RV AC units have roof mounted controls. IF you have roof mounted controls, you MUST leave it on Hi Cool in high ambient and hi humidity conditions to prevent freeze up. MOST RV units have a wall tstat and IF they have a wall tstat, they have a freeze sensor mounted in the evap coil. If installed correctly and functioning, the AC can NEVER freeze up from any parameter. So, if the OP has a wall tstat, he needs to check and verify the freeze sensor is indeed in the evap coil. Doug

i would say the Majority of Rv's ever MGF and on the road have the controls on the A/C units

yes most new middle and high end RV's of "CURRENT" mfg have t-stats on the wall for a/c and heat

don't know when the change over to wall mount t-stat became predominate in sales of new rv's, but, i don't think the are predominate in totality
only in new mfg for the past few years, maybe the past ten, maybe less

Well, lets look at EXPERIANCE. I have 35 years as an RV Tech, we sell Pop-ups to 500K motorhomes. We service ALL kinds. My statement is dead on. Pop ups will have roof mounted controls. Bare Bones small Trailers will have roof mounted controls. These 2 are in the extreme minority of sales. So, as I stated, the majority of RV's will have wall mounted tstats. Doug

Very common problem. Allow me to provide an example of how I used to remove excessive amounts of humidity. This is not practical in everyday use but it does provide a clue as to what happens.

I mounted a 5,000 BTU air unit directly in the path of a 16,000 BTU evaporator/fan outflow. The 5,000 was ingesting the chilled air of the 16,000 BTU unit.

Starting off the humidity was in excess of 70%. Seventy-five or six if I remember correctly. Temperature was in the low mid nineties. Sticky sweaty hot.

Enabled only the larger unit. Watched hygrometer, and thermometer. For the first 15 minutes the hygrometer which was out of the reach of outflow dropped humidity but the temperature dropped perhaps 2 to 3 degrees. Humidity fell to the sixty percent mark, then the temperature started to drop.

After about an hour the humidity stabilized around 58% the temperature continued to go down. When it reached 75 the humidity was still 58%. The big unit could not extract additional moisture from the air.

I started the LG 5,000. Set it to 1st fan speed. It took about 20 minutes or so but the hygometer confirmed that the humidity was being lowered by the 2nd unit without the temperature falling more than one or two degrees more.

I checked outside. The stream of water from the big unit had lessened but now the condensation at the little AC was a steady drip drip drip.

I got the R/H down to around 47 then ceased and desisted.

Time to start sealing up electronic components in food saver bags! Double bagged.

Awoke the next morning, temperature same humidity had climbed back into the mid sixties.

Single stage cooling not so hot for removing humidity. Unless the unit is huge huge and has a recirculator.