central air conditioning question.....electrical...

[bell]

the house i recently moved into has central air, when we were prepping for a second elec box for my fish tank we disconnected the elec stove 220 breaker to run to the second box, what we didn't realize is that this 220 line went to the condenor fan/pump outside. so it's hot out and i wanted to turn on the a/c.......not cold.
i realized the problem and reconnected the original breaker to the 220 line the way it was.....or i think so.
there is the middle uninsulated wire which i remember went to nuetral? (the buss bar in the box) the there is an insulated black and an insulated white, both of these wires went to the large breaker, one on one "pole" the black on the other.......the main in from outside going to the poles are red and black, the red main is on the left side.

it's a/c voltage so if these 2 wires are reversed then the fan will turn one way or the other.....which it does.
is the fan supposed to blow into the condensor or pull air out of it?
the a/c works either way, but i had a big buildup of ice on the condensor pump after a few hours.

i know the "hire a proffesional" warnings i'm going to get, but i know what NOT to do......i have big respect for electricity

thanks

[dad911]

reversing black and white (at breaker) should not matter. Ice build-up is caused by a problem with the system.

[bell]

that's what i was thinking, i also noticed alot of condinsation inside where the exchanger? is above the heater in the main vent......
with the feed/return lines one has foam insulation on it where the other does not, the one that froze was the insulated line, the other seemed kina hot.

if i do reverse the wires the fan does blow oppisite dirrections, the condensor pump runs off of the same line......these need to flow in one dirrection correct?
thanks

[dad911]

Wild guess, but perhaps it is only getting 110 instead of 220. Could 1 leg of the 220 line be loose? I do not think reversing the lines should reverse the motor, unless only 1 leg is getting through.

[fastpat]

220 volt house wiring has four wires in it, two 110 volt wires, a neutral wire, and a ground wire which doesn't have insulation on it. Unless your wiring is very old.

I'm surprised your stove and your HVAC system are on the same breaker, that's not in accordance with the National Electric Code, Each leg of the 110 wires should be on a separate breaker, usually about 30 amps each IIRC, but that would depend on the stove manufacturer's requirements for the specific stove. The two breakers are ganged together so that they are shut off at the same time for safety.

The HVAC system should be on it's own breaker(s) completely, if not then I'd suggest that be rectified as soon as possible.

[jhc]

Usually the ac fan pulls surrounding air in and blows the now hot air out.

[turbo6bar]

Don't see how reversing the two 115V hots will cause the fan to reverse direction, but there's a first time for everything, I suppose.

As jhc states, you want the air pulled up through the condenser and out the top. Causes for a freezing evaporator and suction line (large pipe) include insufficient airflow across the evaporator (heat exchanger above your heating unit), dirty air filter, bad blower motor (beneath your heating unit), and low freon charge.

It sounds like you have a closet unit, and the evaporator coils can get extremely dirty without regular filter changes. If this is the case, you will need to have the system pulled down and have the evaporator pulled and cleaned. Check your filter. Otherwise, I would expect the system to be undercharged.

The stove and A/C condenser really do need to be on separate circuits.

[bell]

there is no electric stove in the house, the stove is gas.
the elec stove wiring was replaced with wiring for the a/c at some time...but never re-labeled on the box.

here is the compressor/fan/condenser unit outside.


there is a big exchanger in the furnace unit which is piped to the outside unit.

the large line is the one that had ice on it, there was also some ice on the compressor.


the a/c works ok, could be alot cooler in my opinion, it's been 90 degree out all day and the coolest the thermostat showed was 82.....house has brand new windows etc......i'm thinking it's just an old unit.
i already replaced the filter...was a little dirty but not too bad.

i'll be calling my landlord this week (i haven't bought the house yet), he said if for some reason it doesn't work well or breaks then he'll replace it with a new unit......this will be done before i buy the house

[North Coast Cab]

Bell,
Congratulations on the new house. Hope it didn't cut into your transmission project.
Anyway, you should have 4 wires between the A/C and the panel and those 4 wires should go through a fused disconnect switch outside. If you don't have one you can get one cheap at HD and it will protect you condensor from spikes or single phasing. The 4 wires are black & red which connect to the 2-pole breaker in the panel, a white wire which connects to the neutral in the panel ans a smaller bare ground wire. If you have the disconnect swtch box outside the white and bare ground both connect to the grounding lug on the box. The two hots, black and red, tie into the leads from the condensor. If yo don't have one, invest on an automatic thermostat also.

John

[bell]

john....tranny rebuild will be done soon hopefully....ed has ordered my parts, engine is out and getting cleaned up, fixing some leaks etc.
i'm not diving into the suspension yet, need to get some bilsiens for the rear and bigger t-bars still (tight budget )

this is the outside box, there are 2 big ass fuses in it.
i have a digital/automatic thermostat



it's not really keeping the house real cool right now, the house is brick so maybe it's just a little "heat soaked" as there is cold air coming out of the vents.
there is no current sign of ice.....maybe something was clogged as it hasn't been used in a year or so.

[dhoward]

Could just be low on R-22. That will cause poor performance and freeze-up issues....

[RickM]

Here's another possibility:

http://members.tripod.com/~jbabs714/acrefrig.htm

"If your system runs low on refrigerant it will freeze up because the lack of pressure means the evaporator (cold coil) will be under the 32 degree mark, thus freezing the water."

If wiring checks out then this may be the case.

Edit....looks like I was typing when DHoward was....

[bell]

good info, the service sticker shows they added 1lb of freon to the system june of 05', anyone know what pressure needs to be in the system? or do system pressures vary on different types of a/c?

[Brian 162]

If you could get gauges and check the pressures on the system that could tell you alot. Check for a blocked evaporator, fan motor going in proper direction, dirty fan assembly, blocked return air, or frozen coil. If you check the above and the evap. coil or compressor is frozen than the charge may be low.

[RickM]

Bell, The pressures are listed on the bottom of the page I posted a link to:

"Pressures on gauges...

The readings on gauges are in pressure psi. If you look at the inside of the gauge there is a pressure temprature chart printed on the gauges for r-12, r-22, r-502. High and low side. Newer gauges have different charts.

Lets look at a few examples.

R-12 on the gauge.

If the pressure on an r-12 system on the low side, while the unit is running is 35 psi.(the outer black colored chart) then look at the smaller circles for the R-12 circle. The needle pointing to 35 psi. also crosses the R-12 circle, look at the corresponding number on it to determine what temperature the coil is operating at. It will be about 38 degrees F'.

If your hi side on r-12 is at 160 psi. then look on the inner part of the gauge on the high side it will read about 120 degrees f.

Lets look at r-22 on the gauge.

If you have a low side of 68 psi. reading on your gauge then look at the inner chart for r-22 at 68 psi. it is about 38 degrees f.

If you have a high side reading at 220 psi. then on your chart the gauge will read about 110 degrees f.

The evaporator (cold coil) on any air conditioning system should never be below 32 degrees f. Why because the condensate (water) on the coil will freeze, freezing up the system.

Freezers and refrigerators keep the temperature of the evaporator (cold coil) below freezing to keep the freezer cold enough to freeze. The coil operates at about 0 degrees f. So with the coil being that cold the condensate will turn to ice which will clog up the coil with ice. This will shut down the cooling. Refrigeraters have a defrost timer that turns on the heaters and shuts off the compressor. The timer keeps the defrost on for about 30-40 minutes. The thawing ice will drain down to the water pan under the frig to evaporate.

If your system runs low on refrigerant it will freeze up because the lack of pressure means the evaporator (cold coil) will be under the 32 degree mark, thus freezing the water.

It seems weird that if you loose refrigerant you would think that the system would warm up but thats not how it works. Think about it.

FOR THE R-134 PRESSURE CHART CLICK HERE> http://members.tripod.com/~jbabs714/chart.htm"

Found this too:

[dad911]

I'm not familiar with that unit, but it looks like the wood chips may be blocking airflow to the bottom. The fan should be able to blow air through the system. Is it supposed to vent out the bottom somehow, or is there a vent on the other side(not shown in picture)?

It would be a good idea to set the unit up on a concrete pad.

[turbo6bar]

I had an identical condensing unit at a rental property. I think the condenser coil is on the back side (the one against the brick wall). In that case, I would expect high side pressures to be through the roof.

There is no perfect pressure reading. It is all dependent on proper airflow across the evaporator and condenser coils. More than likely, this is a system with capillary tube or orifice to regulate freon flow, so you check the charge by calculating superheat. If you haven't done this before, you're better off calling the landlord and having a service man come out. Roughly speaking, assuming you don't have high humidity inside the home, you should expect your supply vent air to be at least 10 degrees cooler than air entering the return vent. The smallest delta I have seen is 12 degrees and the highest was 16 degrees.

I have seen lazy HVAC techs add freon to a system that froze up (they assume it is low on freon), and instead the problem is a dirty evaporator coil. That's why you need someone who can troubleshoot the system properly.

[bell]

i was planning on calling my landlord tomorrow anyway, i just wanted to make sure i had it hooked up correctly after it was disconnected from the main breaker box. wanted to make sure it wasn't my fault

the vent for the condensor is on the rear next to the brick, there is good airflow coming through it.
still no frost on anything, it is working better now than yesterday too.

[914GT]

Let me share with you an experience I had with my A/C unit that even a pro service outfit couldn't resolve. My unit's evaporator was freezing up, and seemed to not have a lot of airflow from the registers. It would freeze up after a short time, then wouldn't blow any air at all. I checked the filter and blower and looked ok. Had an A/C service check it and the guy said pressures were off and the scroll compressor was going bad, drawing too many amps. Was going to cost over $2000 to repair. I told him no thanks, didn't seem right. I looked up the specs and measured the compressor amps myself with a clamp-on meter and they were in spec. I went back to the closet unit, pulled off the bottom cover, and started the blower with the safety interlock switch on the cover pushed in. What was happening was the blower was sucking the fiberglass sound insulation pad away from the side of the unit and blocking off one side of the squirrel cage. With the blower off it would fall back into normal position, which is why I missed it the first time. When the blower turned on it would take a few seconds or sometimes a minute for the insulation to come loose. The factory didn't use enough adhesive to hold it in place. I took the insulation out and the A/C worked great from then on. This was 3-4 years ago. My point is - sometimes it's something really simple that can cause a problem, and that damn repair company tried to rip me off over something that cost nothing to fix.

[fastpat]

Originally posted by dad911


It would be a good idea to set the unit up on a concrete pad.

I was just going to suggest that, moisture trapped under the case is a bad thing.