Front A/C frosts up...

[TXBobcat]

Lately our front Penguin 13.5k A/C is frosting up when we turn the thermostat down low.

We are in Kerrville TX. The temp here has been in the mid 90's and is fairly warm at night. For a couple of nights if we drop the thermostat (dial type on the A/C control panel) low after a while the A/C would start to labor and I checked the condenser fins and they were blocked by frost.

Anyone have an idea why we can't turn the thermostat down low without getting it all frosted up. Makes the bedroom a bit warm at night.

BC

 

[jbeletti]

Bob, were you running the AC fan on Hi or Low? Most say that when run on low, under certain conditions, the AC wil freeze up as not enough air is moved across the coils to keep it from frosting. I'm no expert in this area by any stretch - just something I've read on the forum a couple of times.

Jim

 

[TXBobcat]

I always keep the fan on our A/C's on high. I also have cleaned the filters. Heard that if the filter is not clean it will restrict the flow of air and cause it to freeze up.

David at ElploreUSA in Seguin taped up around the inside so it would not freeze. He said if the unit was pulling in air that was already cold it would cause a freeze up.

I have one duct from the front A/C that is positioned under the edge of the bedroom A/C. David taped up the vent so it would not effect the bedroom A/C, but it still freezes up. Not all the time, just when I turn the thermostat down almost all the way. If I raise the thermostat up to a higher temp it will not freeze.

Thanks
BC

 

[mmomega]

The key is not turning it down too low to quickly, work it down to where you want it if it's warm out. **** I've had a fairly large AC unit completely frost over in Kuwait in the middle of the summer because someone thought dropping it to 55 in 125deg with 85-95% humidity was a great idea. The entire unit practically froze over white, was kind of funny to see but not so much that they had to then turn the AC off for an hour or so to defrost it then gradually work it back down to 65'ish. Also I've usually only seen this in higher humidity climates, I'm guessing the moisture in the air is just freezing when it comes in contact with those cold fins.

On another note, it's quite a shock to the body to immediately adjust to a 60 deg temperature change in either direction. It was either bursting in sweat when you stepped out or walking into a meat cooler coming in.

 

[YaShouldaGotaDiesel]

It could also be that the Freon is low due to a leak or a recent a/c service was done and to much Freon was leaked out. If you can have an a/c technician check the pressure, it should be 60 psi to 65 psi on the low suction side. 61psi being the best efficiency for a Freon 12, Freon 22 and Freon 134a. If the pressure of the Freon goes below 60 psi, which is what I suspect is your case, the a/c unit will freeze over.
Or like everyone else has said, if the air flow across the coils is being blocked due to dirty air filter or by some other means, they will frost over and in a real bad case of, I forgot all about that air filter 2 years ago, it will freeze over.

 

[hoefler]

Also check to see if the short piece of duct is intact and has no leaks. If it is leaking, it will go directly to the coil and cause you to freeze up prematurely. I have the same unit in our Landmark and always run the fan on low. We like it in the low 70's, high 60's when we sleep. Be in Ms with 108* temps and very high humidity and never had an issue keeping cool.

 

[ATLJOHN]

Butch from RV"S for Less advised that in hot weather to leave the fan on and NOT set to auto in order to keep the unit from icing up.

 

[TravelTiger]

We have had the same issue this weekend as the OP with the Penguin (non-ducted, controls on the unit). At night, usually early morning (outside temp in the 70s), the front AC stops running on high fan... it's running, but a speed that sounds barely over the low speed.... It's the dead of night so I can only assume it's frozen up (not going to wake everyone to investigate). Turn it off, and try to turn it on again, the AC will not come on at low or high, at any temp setting. Turn it to fan high or low, it sounds about the same. Wait an hour or so, turn it on, works fine. When I have had this problem last year (under warranty), it was in Arizona... When we got back to Texas, the dealer could not recreate the problem. Now it's a year later (out of the original 1 year warranty). What would y'all suggest? Take it back to the dealer that originally couldn't solve it, or somewhere else?

E

 

[57chevyconvt]

Not sure about the Penguin LP units, but the Quick Cool 13.5K and 15K units have a thermal cut out switch/sensor attached to the evaporator coil that controls the compressor run cycle. When the evaporator coil reaches about 38 degrees the switch will open and the compressor stops. When the evaporator coil warms to around 54 degrees the thermal switch closes and the compressor restarts. I have fixed a number of units where the thermal switch was not installed or improperly located by the factor or dealer installing tech, because of the marriage of the upper unit with the lower unit controls inside the RV were not followed as per Dometic instructions. All of this hardware needs to be installed and working properly to prevent the evaporator from freezing the moisture that collects on the evaporator coil. You might want a qualified tech to out this possibility.

 

[hoefler]

Run the fan on high, and turn the temp down on the main unit as well.