Air Conditioning - New Install Problems

Just got a new Ducane 4 Ton 12 Seer with new A coil installed yesterday (WED) and it don't work. The techs are coming back in the morning (FRI) but I need to be prepared with some knowledge.

A large chunk of ice has formed at the valves on the condensor on the large pipe also inside there ice build up. Also the entire condensor is encased in ice

The thin line is air temp.

The tech did check for leaks for about 1/2 hour - 45 minutes by applying negative pressure to the system prior to opening the valves at the condensor.

Any ideas to the problem in advance ?
Could I have done damage to the unit for running it about 26 hours ?

Could have damaged it, but it is a new unit, under warranty. You shouldn't have to pay.

If you don't use a micron gauge, there is no way to "check for leaks" with a vacuum pump and a watch. Sorry, can't be done. Anyone that says otherwise is full of it. Small leaks will still allow the system to pull into a vacuum or hold pressure for such a short period of time. These small leaks are large enough to vent quite a bit of refrigerant, which is under pressure when the equipment is operational.

The ice must be thawed before the techs show up and attempt to fix it. A 60 watt incandescent bulb (not halogen) on a trouble light in the plenum does the trick overnight. Humidifiers make nice access holes. :D

Shut off all power at the unit and the turn off the tstat. Open the unit doors and set up a fan to circulate some air in there. Water will overflow.

Lots of luck.

I totally agree with danski0224 on the use of a micron gauge. There are other factors which may have caused the system to freeze such as a dirty air filter, closed or blocked supply or return vents, a "short" factory charge (this should have been checked upon installation) or a leak in the outdoor unit (this would not have been detected by use of a micron gauge). Something similar happened to me several years ago when a factory joint in the outdoor section started leaking after start up. When you find out the problem, let us know.

I took off the ductwork, I also have a herrmidifer which lands a 5" duct right on the left side of the A-Coil (which is frozen of course) perfect access point for a light. I also took off the door to the fire box and put a second light there. Not sure what the Plenum is. Can you tell me what a Plenum is ?

On the firebox I noticed a lot of what look liked rust but when I tapped it lightly it all fell away in big pieces is that soot build up ?

I shop vacumed it up. I do have the furnance checked and serviced yearly.

If it is brown, it's rust. If black, soot. Neither good.
The plenum is the box which contains the A-coil & the area above it up to where the main duct(s) take off.

Light worked great unit was thawed by morning. Unit was short on Freon so much for the unit being pre-charged for 15' of line set & coil. The unit was checked at all fittings for leaks none found, the tech added dye just in the off case there is a problem with the coil or condensor. Then charged the unit to 64 psi back pressure and 170 psi at the head. Then called the office wanting to know why the unit was not checked at install. house got to 70 in a few hours (new york metro) so its warm today.

Any way the new concern is the hermidifer. I have the one with the rotating sponge in the little tank of water (I have well water so its untreated), this tech and my heating guy both said they don't like them, they are prone to bacteria in the water and can do more harm to your health than good. I also have heavy mineral content in the water and it shows in the tank (green sponge from coppeer some white creamy stuff also) they suggested I look into other BETTER systems to increase humidity in the heating season - any ideas or thoughts.

Also I do have the furnance serviced yearly but when going through all this as the vent pipes were off there waas a bit of soot on the fire box and a bit of rust in the vent pipe (I have a power ventor to the outside). How much soot is normal in a year amd how much rust is normal (I had a couple cups of rust). (I burned about a thousand gallons last season to give an indication of use) I'm thinking when the wind blows the rain a certain way is coming into the power ventor. Ideas ?

Ideally you should have no soot but I would not be concerned about a dusting. Any build up is too much.

Some rust is normal. Large flakes or very fine (finer than sugar) does not concern me unless there is a lot of it. If you get rid of the humidifier the rust will be reduced significantly.

If you insist on having a humidifier, get one or more of the free standing type. Humidifiers, unless downstream of the heat exchanger are a major furnace killer.

Then charged the unit to 64 psi back pressure and 170 psi at the head.


Out of curiosity, what was the outdoor temp and indoor temp when they charged it to this level??

I missed the part about the pressures. Unless it was a cool day & the house was cool, they sound low but without a charging table for your equipment in front of me, I can't tell for sure. The best way I know, short of pulling out all the refrigerant & weighing in the proper charge, is to charge by superheat. I too would like to know at least the indoor & outdoor temperatures

He did indicate that the uint was charged till system took no additional charge.

Oh boy :confused: You may be ok but I wonder. It may be worth it to call the installing contractor and request they check the charge using subcooling/superheat depending on what metering devise was used.

Rules of thumb: (1) You get what you pay for. (2) The cheaper the oil, the more extensive filtration you need. So in a nutshell, yes the oil could be the source of your soot problem, but there are also a lot of other factors.