Evaporator Freezing

[templeandgary]

Hello,

I just got back from a week trip and when I parked my Class A Diesel Morohome I noticed a lot of water dripping out of the front.  I know this is normal after running the AC because of condensation but this seemed like a lot.  I pulled out the Generator slide and saw it really dripping from out of either the Evaporator or the Condenser.  Not really sure which on it is, I thought it was the Condenser because in a car its up front but maybe the items are located differently in a Motorhome?  I saw the water dripping out from both sides and all over the wiring and I noticed that none was coming out of the drain hose.  I quickly figured out that the hose was plugged up so I solved that problem but while I was feeling around for leaves and junk to clean out I felt the veins on the Evaporator/Condenser and I felt a layer of Ice on it.  Is this normal?   I will attach a Picture of the part that was iced, again either the Evaporator or Condenser, not sure which part this is.  I just want to know if this is normal or if I have a problem with the AC in the coach. It was blowing cold so I assume its okay?

[hermanmullins]

The best I can suggest is to check the drain hose. If it is clogged up, clean it out then run the A/C. That is the least expensive thing to try. Sorry, I didn't ask, how was the unit cooling before you got home? Good, Fair or poorly?

Herman 

 

[wolfe10]

That is the EVAPORATOR. 

What brand is it?

Does it freeze up even with fan on HIGH?

[templeandgary]

Not sure on the brand, back in storage.  I don't think the fan was on high, probably about half.  Would that make a difference?

Thanks for your help.

[templeandgary]

Sorry, motorhome brand is Entegra, not sure if that is what you meant.  The Evaporator brand I have no clue.

[dickandlois]

25 minutes ago, templeandgary said:

Sorry, motorhome brand is Entegra, not sure if that is what you meant.  The Evaporator brand I have no clue.

From your description it sounds like the Expansion valve is the problem. It prevents icing by turning off the AC compressor when the sensor, located in the evaporator senses a temperature at or below 32 deg. This allows the ice to melt. As soon as the temperature is above the freezing point the Compressor circuit is enabled again. and the beat goes on. 

In most class A coaches one needs to remove the front portion of the heater box . They do very though. Best to contact a good AC shop familiar with servicing Class A RV air conditioning systems. The hrs. of labor depends on how much needs to be removed to access the valve. If the Freon lines need to be opened. the system needs to be re assembled, a vacuum test then recharged with about 2 1/2 lbs to 3 lbs of Freon in most cases. 

You did not offer the year and make of your Class A. the Age of the coach can affect the type of Freon used.

Rich.

[hermanmullins]

Gary, not sure what year your coach is but if you had a build sheet that may tell you who was the manufacturer of each component. 

Knowing that your coach is an Entegra now someone with the same unit may have had the same issue.

Also as I asked, how was it cooling when you saw all the water?

Herman 

[templeandgary]

Sorry for the lack of information.  The coach is a 2018 Entegra Insignia 45ft.  It was produces in 2017 but I think the Chassis was built by Spartan at the very end of 2016 if memory serves.

I drove the home from the campground which was only an hour away, the temp out was around 75 and I only had the AC on about half power.  I got home, unloaded the coach and about two hours later drove to the storage facility which is only about 20 min away.  About 20 min after parking to store it I noticed all of the water.  I opened the Generator door and thats when I noticed the drain tube was clogged.  I saw that the whole evaporator was wet and the bottom inch had a layer of Ice on it which was melting quickly.  The AC was blowing cold the whole time but I did notice a musty smell in the coach when I got in it at home to drive it to the storage facility.

[hermanmullins]

Thanks Gary, since you cleared the drain tube take it out in a few days and see how it does. You may have solved your problem. 

Herman 

[rayin]

Perhaps this website will offer some insight to A/C charge requirements This for a Foretravel MH: http://www.beamalarm.com/Documents/dash_air_conditioner_refrigerant_and_oil_capacity.html

I've been told a low charge will cause freezing too, but I suspect the root of your freezing is the plugged drain and low air flow. IMO it is better to reduce cooling temperature than reduce air flow..

Mine was low when we bought the MH. I bought a large can of refigerant with a pressure gauge and filled to when the gauge read in the full range. That was 2013, it's been operating great ever since.

[bm02tj]

Poor air flow bad TXV or low on freon will cause it to freeze up 

A plugged condenser or bad fan in some cases can cause high head  and also higher amperage to operate which can help cause freezing 

[templeandgary]

Thanks for your help everybody!!

[rayin]

I do not intend to be insulting, but I thought this diagram might help understand the working of an air conditioning system: https://www.btrac.com/documents/svc-manual-revision-i-feb-2011.pdf

[dickandlois]

Mentioned the expansion valve. The other items listed could be playing the same game. Pressure levels, easy to check with a manifold gauge set. cleaning the drain could be, but the coach is relatively new. So there should be a small build up of unwanted material in the drain in the heater box.

The system could have a newer version of Freon, that was used while charging the system ? However the newer chemistry could have unwanted reactions in the expansion vale assembly?

Expansion Valve: This small valve controls
the flow of refrigerant into the evaporator.
It is controlled by a temperature sensor at
the evaporator outlet. If the outlet temperature
is too high, it means not enough
refrigerant is flowing into the evaporator
and the result will be poor cooling.
If the outlet temperature is too cool, it
means too much refrigerant is flowing and
the evaporator fins will probably load up
with ice. In either case, the feedback
temperature sensor opens and closes the
expansion valve opening to achieve the
correct flow rate and evaporator outlet
temperature.

Rich.

[templeandgary]

15 hours ago, RayIN said:

I do not intend to be insulting, but I thought this diagram might help understand the working of an air conditioning system: https://www.btrac.com/documents/svc-manual-revision-i-feb-2011.pdf

Not insulting at all.  I wouldn't be asking if I was an expert😉  This article was very helpful.  Thanks!

[jsymmes]

My evaporator looks just like yours.  I have a 2019 Dutch Star on a Spartan chassis.  When I emailed Evans Tempcon which is now ProAir, LLC.  I was told that Evans Tempcon installed the evaporator thermostat sensor in the wrong location.  It was not installed in the coldest location in order to sense a freezing condition.  The cure was to move the evaporator temp. sensor to a new location.  I will be getting mine relocated under warranty in the next month.  Mine iced over and when I stopped (fresh vents open) driving the water was dripping everywhere as the ice melted off the evaporator coil.

You might want to go to the ProAir webpage and send them a note for more details on the proper location for the evaporator thermostat bulb location.

My Evaporator...

[huffypuff]

On 4/19/2020 at 7:11 PM, templeandgary said:

Sorry for the lack of information.  The coach is a 2018 Entegra Insignia 45ft.  It was produces in 2017 but I think the Chassis was built by Spartan at the very end of 2016 if memory serves.

I drove the home from the campground which was only an hour away, the temp out was around 75 and I only had the AC on about half power.  I got home, unloaded the coach and about two hours later drove to the storage facility which is only about 20 min away.  About 20 min after parking to store it I noticed all of the water.  I opened the Generator door and thats when I noticed the drain tube was clogged.  I saw that the whole evaporator was wet and the bottom inch had a layer of Ice on it which was melting quickly.  The AC was blowing cold the whole time but I did notice a musty smell in the coach when I got in it at home to drive it to the storage facility.

I don't know about your 2018 my but my 2019 Anthem has the condenser right below the evaporator so it's not pumping cold freon 45 feet and be more efficient.  If blowing cold inside then check drain.  If evap freezes up you will notice less air flow and less cold.  

Sorry I see you clear the drain, you may had solved the problem, 

[Catman300]

On 4/19/2020 at 10:17 PM, templeandgary said:

Thanks for your help everybody!!

When your DRAIN hose was clogged,that means the condensation/water had to go somewhere,so it builds up inside the evap box then runs out along the seam where the box meets the coach.When you turn,or stop,it cause the water inside the box to slosh making it seem like excess evaporation.All of that extra moisture not draining may have caused ice to form on the coil fins. I am sure you fixed the problem by cleaning the drain hose.

_______________________________________________________________________________________________________________________________________________________________________________

On a side note...I just got thru completely refreshing my 2000 Newmar Dutchstar dash AC system two days ago due to the compressor locking up. New Valeo (made in Japan,NOT a China look a like) compressor,new expansion valve,new air drier,flushed out every line,evaporator,and condenser. Pulled and held 30hg's vacuum for 2 hours.Filled with 6oz of PAG46 oil in compressor,2oz in the Dryer,and 4lbs or 134A refrigerant.That baby blows 38* out or the center vent on medium fan.Saved a LOT (TONS) of money doing it all myself,and O'Reilly's  tool loaner program.Goodluck to you.

[txiceman]

On 4/19/2020 at 8:56 PM, DickandLois said:

From your description it sounds like the Expansion valve is the problem. It prevents icing by turning off the AC compressor when the sensor, located in the evaporator senses a temperature at or below 32 deg. This allows the ice to melt. As soon as the temperature is above the freezing point the Compressor circuit is enabled again. and the beat goes on. 

In most class A coaches one needs to remove the front portion of the heater box . They do very though. Best to contact a good AC shop familiar with servicing Class A RV air conditioning systems. The hrs. of labor depends on how much needs to be removed to access the valve. If the Freon lines need to be opened. the system needs to be re assembled, a vacuum test then recharged with about 2 1/2 lbs to 3 lbs of Freon in most cases. 

You did not offer the year and make of your Class A. the Age of the coach can affect the type of Freon used.

Rich.

Wrong description of a Thermal Expansion Valve ....TXV.  The TXV regulates the refrigerant into the evaporator coil by measuring the evaporator pressure and the superheat leaving the coil.  There may be a temperature sensor embedded in the coil to sense icing and this would shut off the compressor on low coil temperature.

Ken