Community Forums

kcirick · 08-21-2019, 09:58 AM

Hello,

We recently bought a new RV trailer (Wildwood FSX 178BHS). We took our first trip this weekend which went smoothly except for one thing.

We put on the AC through the night because it was very hot and humid. The AC unit worked well and without any problems. The morning we turned off the AC and went out for a swim. When we came back, there was a puddle under the AC unit and found out it was coming from the ceiling mounted AC unit. I popped the air filter and found there was some ice build up inside which was melting and dripping out of the AC unit.

I am trying to figure out if this is something normal, or if I need to go back to the dealer to have it fixed (it is still under warranty). Am I doing something wrong (should I have had the unit to "low fan" after turning off the AC, for example)?

I can provide additional info. Thanks in advance for your help and insights!

jergle · 08-21-2019, 11:06 AM

Ours will occasionally do that if it is very hot and humid, and we have it set to the coldest setting where the compressor doesn't really cycle off for a long time. If we cut the setting to just a little warmer where it cycles every now and then, no problem.

Old-Biscuit · 08-21-2019, 11:11 AM

Hot & Humid.......therefore lots of condensation accumulating from Evap Coil
Ice forming on Evap COil is not unusual in humid conditions
CLEAN return air return, fan on HIGH and Evap Coil drip pan drain holes free & clear so condensate can run out

puttin · 08-21-2019, 11:30 AM

And use the highest fan speed too. Lower fan speeds can help the coil get iced up faster especially in hot humid conditions where the ac runs constantly.

kcirick · 08-21-2019, 11:44 AM

I just want to clarify that it is not a thermostat activated AC, it has a dial for high ac, low ac, high fan, low fan... so when I have it running at night, it's on all the time (I assume).

Also, because it is a brand new unit, I don't think there's nothing to clean? during the night, I see water running down the roof, so I assume drain pipe is working properly when the unit was on.

jergle · 08-21-2019, 01:05 PM

Does your ac not have a dial allowing you to adjust the temperature of the ac (a thermostat of sorts)? All of the RV AC's I've used have one dial for low fan, high fan, low ac, high ac, and a separate dial (usually with blue for cold, red for warmer) to control the temp. That's the adjustment I'm talking about. We only have freeze up if we leave it all the way to the cold (blue) side.

kcirick · 08-21-2019, 01:31 PM

Quote:

Originally Posted by jergle

Does your ac not have a dial allowing you to adjust the temperature of the ac (a thermostat of sorts)? All of the RV AC's I've used have one dial for low fan, high fan, low ac, high ac, and a separate dial (usually with blue for cold, red for warmer) to control the temp. That's the adjustment I'm talking about. We only have freeze up if we leave it all the way to the cold (blue) side.

Ah yes, it does, indeed! and I believe I had it pretty much to the coldest. I also had it on low cool, I don't know if that affects anything... I'll keep that in mind. Thank you!

Itchytoe · 08-22-2019, 08:58 AM

Your AC is a little bit overcharged. The coil shouldn't get below 32 degrees (0 if you're not in the US). Ideally, it would stay around 35 to 40 degrees. Ice shouldn't ever form on your coils in a properly charged system. Unfortunately, many rooftop systems, including mine, are overcharged from the factory and not servicable so there's no way to fix the problem.

Best way to fight the problem is to keep the fan running on high, and only cycle the compressor. Or you could replace the unit with another one that may or may not be ovecharged also. I think replacement runs about $1,000.

Persistent · 08-23-2019, 06:35 AM

Coils should not build up large amounts of ice if the AC has been designed, built and installed correctly.

That said, a lot of automotive and RV AC do build up ice. The strategies list in above posts are all good.

Two thing keep ice from building up on AC evaporator coils.
1) Air flow over coils brings hot are into the unit. The heat keeps the coils above 32 degrees.
2) The refrigerant flow inside the coils. I know less about exactly how this works, but low refrigerant pressure causes it and improper bleed into evaporator coils causes it.

Certainly taking it in for warranty work may solve the problem and avoid having to replace or repair it soon after warranty expires. However, the wait time and likely hood of actually getting it fixed in time to test it before the humid season is over should not get your hopes up.

**Spdracr39** · 08-24-2019, 07:27 PM

Make sure the return air side and the pressure air side are separated. There is a divider there that should seal them off. Some good havc tape will keep the air from mixing.

Dom · 08-24-2019, 07:43 PM

Quote:

Originally Posted by Itchytoe

Your AC is a little bit overcharged. The coil shouldn't get below 32 degrees (0 if you're not in the US). Ideally, it would stay around 35 to 40 degrees. Ice shouldn't ever form on your coils in a properly charged system. Unfortunately, many rooftop systems, including mine, are overcharged from the factory and not servicable so there's no way to fix the problem.

Best way to fight the problem is to keep the fan running on high, and only cycle the compressor. Or you could replace the unit with another one that may or may not be ovecharged also. I think replacement runs about $1,000.

Over charge does exactly the opposite. Your evaporator temp rises with an overcharge. 40 years experience. I think the OP has it dialed in. Temp control was set to max

Itchytoe · 08-24-2019, 08:41 PM

Quote:

Originally Posted by Dom

Over charge does exactly the opposite. Your evaporator temp rises with an overcharge. 40 years experience. I think the OP has it dialed in. Temp control was set to max

I am by no means an HVAC expert. Thanks for the correction.