Got an AC warning, thoughts?

[ls1ashley]

I’m attaching a picture showing a warning I got twice on my recent trips.

Thoughts? I’m apt to ignore it and assume one of the units worked a lot harder than the others and that it turned itself off to protect it. And, no harm and all systems are working fine. I should perhaps consider what I set each of the units on in the future.

Anyone think I’m all wrong?

[BFlinn181]

You might take down the ceiling cover on the rear A/C unit and make sure the sensor is in the proper location. They've been known to drop off the fins of the evaporator.

[intercept]

Hi,
The sensor will show a fault like this when it sees a temperature in the evaporator coil less than 32 degrees F. At that temperature the condensed water on coil will freeze and ice will build up. The air flow will drop off as the ice plugs the coil up.

The sensor will not see a low temperature if it falls off of the coil. The coil will be able to freeze and the flow reduce to zero without a fault showing if the sensor falls off of the coil.

This fault indicates you have either low freon in the systems, or too low an airflow for the humidity in the coach.

I would start with 1 and 2 the easy cheap fix first.

1) Clean the inlet AC filters
2) Turn up the fan speed
3) Raise the thermostat some until the compressor cycles off then lower it 2 degrees at a time so it cycles off again. Sometimes icing happens if you try to cool a very hot/Humid coach too quickly.
4) Hope 1, 2, and 3 fix it.

Good Luck

John

[ls1ashley]

Thanks intercept,
That sounds right. I think it was just too hot and the other units weren’t pitching in enough. It’s an all new coach so I’ll be ticked it I have low Freon. I will keep an eye on things though.

[BFlinn181]

Besides increasing the fan speed, make sure all ceiling ducts are open. You can divert the air aiming it away from hitting you directly, but don't shut off the vents.

[wa8yxm]

Ok, What it means. Air conditioners (Some of 'em) have a Freeze or Frost sensor, a thermometer that is inserted into what hopefully is the coldest spot on the evaporator coils.. IF this drops below 32 degrees F (zero C) there is a chance of ice forming from the water condensing out of the air and blocking air flow basically shutting down teh A/C. As the ice builds more and more the air flow is reduced and the ice builds faster till it's blocked.

What causes it?
Several causes.. Many have suggested low air flow is a cause. this can be cuased by running fan on LOW or by Dirty filters or more likely both.

I've seen it on several pieces of hardware with LOW Refrigerant levels.

Recommended procedure is clean filters and such. Run fan on HIH not Auto. See if it keeps happeningk if it does Seek professional help.

[BFlinn181]

Rooftop A/C units don't have valves, the pressures can't be checked or refrigerant added. Some will chip in with the suggestion to add piercing valves to allow pressure checking and refrigerant supplementing, but on a unit still under warranty, I wouldn't recommend it. The piercing valves usually end up leaking and don't solve the problem of why the refrigerant was low in a sealed system.

I really think your issue is one of high humidity. In the other instances you saw this warning, was it soon after turning on the A/C or after showers, cooking, etc? Has it ever happened with the fan on any setting other than low? Before calling for service, try running the fan on a higher setting and check your filters. If you still get the displayed warning on a higher fan speed, immediately visually check if ice is present on the evaporating coil, if so, then you should get the unit replaced under warranty.

[tjvogtiii]

great insight and information

[ls1ashley]

Thank you all so much for the detailed responses.

I would say that yes, we've noticed it after 1) a long drive and 2) after everyone showered.

So far, it's not happened again, and during driving, we've avoided the "auto" setting and kept a little closer eye on the temperature settings. They seem to do a good job overall so I think it's more of a fluke, but it (and we) are new so figured it doesn't hurt to ask.

[garykk]

Run the exhaust Fan when showering, helps with removing moisture

[powerboatr]

coils being dirty and low airflow across the coil will set this easy.