Community Forums

ZTedster · 10-12-2011, 02:29 PM

Here is a pic of the AC on our 2006 Gulf Stream Cavalier.

The arrows are showing a line and a canister. The white you see is ice.

Should I insulate these lines? I can encase them with foam or just plain old tubing insulation; the black foam rubber sleeve type that slips over the pipe.

Suggestions?

Ed ke6bnl · 10-12-2011, 03:37 PM

Quote:

Originally Posted by ZTedster

Here is a pic of the AC on our 2006 Gulf Stream Cavalier.

The arrows are showing a line and a canister. The white you see is ice.

Should I insulate these lines? I can encase them with foam or just plain old tubing insulation; the black foam rubber sleeve type that slips over the pipe.

Suggestions?

I think that would be helpful, IF the indoor coil or filter is dirty or plugged the air will go through the coil at a much slower speed and it can cause the coil to ice up, although many a/c's will di this icing at start up and it will go away as the outside condenser coil get hotter and its pressure increased and with that the suction pr. increases and then goes to sweating rather then icing. check the coil and filter first. My suggestion ED

ZTedster · 10-12-2011, 04:51 PM

This AC doesn't run a de-icing cycle. It's a straight forward air conditioner with no-frills.

We keep the filter clean and have no problems with the interior coil freezing up. I was just looking for ways to make it more efficient and to maximize the capability of this AC.

I was pretty sure those lines could be insulated, just wanted to gather as much info as possible to make sure I don't mess this thing up

TXiceman · 10-12-2011, 06:29 PM

One of tow things will cause the line to ice up. Dirty evaporator coil or filter (low air flow) and low refrigerant.

The line will normally sweat as it is running below the dew point of the air most of the time....but it should not ice on the line. Your coil could still be dirty.

If it makes you feel better you can insulate the line but it is not necessary.

Over 40 years experience with A/C and refrigeration.

Ken

Rodneykrantz · 10-12-2011, 07:09 PM

Are you running it with the top off? The air has to go across the coil if not that will cause it to freeze up also

HeatAir · 10-12-2011, 07:12 PM

Icing suction line: Low air flow or low refrigerant.

Low air flow: Dirty filter, fan not working, dirty inside coil.

Low refrigerant: Self explanatory.

Third choice: Low ambient (outside temps). Open a window?

As a rule, most camper units are sealed with no refrigerant taps that are active. They will last a long time but all systems leak at some point.

Insulating the suction line will hide the problem from plain sight but won't cure anything.

I'm a puppy with only 31 years doing air conditioning and refrigeration. Been licensed in my state 1992, 8 hour test. Passed the test the first time!!

REAL sig line:

2003 Four-Winds Hurricane 30Q
2005 Jeep Liberty CRD (hers)-L
1985 F150 (his)-J
1988 Son (ours)
1990 Daughter (ours)

2006 E250 work van (ugh)

LadyFitz... · 10-12-2011, 07:22 PM

Quote:

Originally Posted by TXiceman

One of tow things will cause the line to ice up. Dirty evaporator coil or filter (low air flow) and low refrigerant.

The line will normally sweat as it is running below the dew point of the air most of the time....but it should not ice on the line. Your coil could still be dirty.

If it makes you feel better you can insulate the line but it is not necessary.

Over 40 years experience with A/C and refrigeration.

Ken

I don't have the Iceman's credentials but I agree with him about low freon and/or low airflow over the evaporator (the coil that gets cold) being the cause. Low airflow can be caused by a dirty evaporator (dirt also impedes heat transfer), a dirty filter, blocked ductwork, or too many registers closed or only partially open.

I would suggest first cleaning or replacing the filter. If that doesn't work, open all the registers and make sure all of them have air coming out. If that doesn't work, very carefully clean the evaporator (the fins are very fragile). If that fails, you probably have low refrigerant. RV roof top A/Cs usually (if not always) do not have ports for checking or adding refrigerant. They can be added and leaks sealed but labor costs would be so high, you would be better off replacing the unit.

TXiceman · 10-12-2011, 07:58 PM

Heat Air is right in his post. Also, low air across the condenser coil (the part that blows up on the roof) will cause high pressure in the condenser and high amps at the motor....not freeze up the suction line or evaporator coil.

I have spent a lot of time in the field, but I am a mechanical engineer majoring in heat transfer and thermodynamics. HeatAir is a technician and knows more about the little day to day things on these units, but still has to understand the thermodynamic basis in order to trouble shoot them. I design them. Engineers need technicians and technicians need engineers.

So there is 42 + 31 = 73 years of experience here between the two of us.

So STAY COOL.

Ken

ZTedster · 10-12-2011, 08:03 PM

Thank you all for the superb advice.

Nothing is wrong with the AC. It works very well. I was going over the roof, checking all the caulking, and getting everything nice and tidy before washing the trailer down.

I popped off the shroud on the AC to clean out any squirrel nests and whatnot. There was only a wasp nest and a cocoon with something big, juicy, and slimy in it. Other than that there were just some pine needles. I combed the fins straight on the exterior coil, checked the blower, etc.

But then the AC fired up, I saw that line starting to frost, and thought, "Hmmm, I could be losing a tad of cooling there." But before insulating it, I knew this forum has some professional HVACers and decided to see if it would hurt the system if it was insulated. Oh, and the temperature was about 80 degrees, but the humidity was around 70-80%, so something that cold is certainly going to frost up.

I used foil tape to seal up the plenum and return real good. Earlier, when changing out the exhaust fan in the bathroom, I could feel cold air blowing through the rafters, which meant the ductwork wasn't properly sealed. The plenum just had a quick tape job done at the factory. It wasn't all that good because they were cranking these things out as fast as they could. It took a good hour to seal the plenum to the duct inlets, but it paid off. Now that everything is put back together I get much better flow out of the registers. I taped up the divider between the plenum and return as well. This thing is working better now.

Thanks again, folks. I'll get some tubing insulation tomorrow and insulate that line and canister. Might get 1/10th of a degree more efficiency out of it.