[wreedlbz]

Hello,

I recently purchased a home with a Lennox 12ACB48 unit. The unit would not cool very well so the sellers had it serviced and freon was added and fan motor replaced I believe. Vent temps went from mid 70s to 59-64 around the house. Today it was very hot outside (Houston TX) and the unit stopped cooling. It was blowing 84 out of most vents and the compressor was blowing somewhat cool air out the top. I turned the thermostat off and back on after a few minutes and everything seems to be fine for now.

Can anyone help me with what is going on? My uncle a competent engineer came over and put gauges on the system and they were OK he said. I have a service call scheldued with my home warranty, but I trust this site way more than any tech from the home warranty company.

Any ideas as to what is going on?

 

[wreedlbz]

anything else i should ask them to do to make sure they dont tell me nothing is wrong as the syste is working fine now?

 

[wreedlbz]

Coil in the attic was very dirty and needs to be cleaned. Coudl this have caused it? I did change the filters to the 3m ones, maybe this cause it to be way too restrictive. I have changed back to the cheap filter until we clean the coil.

 

[wreedlbz]

It took several hours for me to realize it was not cooling, I was asleep. I believe the compressor cut off and then me cycling the switch the few hours after i noticed it caused it to come back on. Does that make sense? So it probably did have several hours to thaw out.

I purchased the 3m filters with a MERV11 rating, I assume a MERV 7 or 8 is preferred because it is less restrictive?

 

[wreedlbz]

Thanks,

Anything else I can do to get this thing maintained better?

 

[wreedlbz]

Flush the outdoor coil with a garden hose and sprayer once a month. Have the freon checked once a year. Use window blinds/drapes/shades and shade trees to lessen the load on it. Seal up the attic hatch and door gaskets so they don't leak air in/out.

Flush outside coil from the outside in?

 

[wreedlbz]

OK So the tech came about a month ago and said the coil was dirty and it needed to be cleaned. I let him clean it (very very dirty) and the system ran fine for about a month now and it just did the same thing again. Fan running, but compressor not and not cooling. I shut the system off and sprayed it with a water hose and waited about 10 minutes and low and behold it is cooling again right now.
What could this be?

 

[wreedlbz]

Can these things be checked when the compressor is working properly? I sprayed water on it and it is working fine now.

 

[wreedlbz]

I would bet good money that the txv screen is dirty. You would need the tech to come out again to diagnose this.

Can I clean the screen myself? I assisted with the cleaning of the coil so I know my way around the Air Handler. Where exactly is this screen located?

 

[wreedlbz]

My uncle came over and added a hard start kit. We are also going to replace the run capacitor next week.

I will check into the TVX screen.

 

[wreedlbz]

Well I just came home and it quit again. Fan was spinning but compressor was not running. Where to look now?

 

[wreedlbz]

Yes I believe I do.

 

[wreedlbz]

How do you know the compressor is off?

outside unit not making as much noise and the freon lines are hot, not cooling. im just guessing i really dont know.

 

[wreedlbz]

So i just turned the system off for about 20 mins. I just clicked it back on and the air handler starts up but the outside unit is just buzzing, the fan is not even spinning now.

 

[wreedlbz]

Well it might only have the thermal overload switch open in it if it got too hot. Without doing anything to any wires run your water hose on the condenser, mainly on the compressor for a good ten to fifteen minutes.

If it was running and got too hot then running water over the compressor will cool it off enough to close that switch which is internal versus being a reset button someone can simply push.


if you don't run water over it you're looking at a possible 4-6 hours for it to cool off on it's own.

again, this is only one possibility, that the thermal overload is open.


try that and if it doesn't come on than I'll walk you through how to test the motor with continuity.

The water trick, has worked the last 2 times. I will go do that now.

 

[wreedlbz]

OKey dokey, water did it. It is cooling again. This is now the third time this has happened. So far we have cleaned the coil, charged the system and put a 5 2 1 hard start kit on it. What else should we do?

 

[wreedlbz]

So now we know that your comrpessor is getting too hot which means the refrigerant levels need to be checked and the condenser coil needs to positively be cleaned. That and the evaporator.

I'm not suggesting that the windings aren't weak and the compressor is not on it's last legs as that very well could be the case (although the thermal overload switch is there to protect the compressor) but these are the reasons compressors go out; lack of air flow (restriction/dirt) through the inside (evaporator) and outside (condenser) coils and or refrigerant problems which stem from lack of air flow or leaks.

I'd sure like to know the pressures on that thing once it's running for about twenty minutes. I don't take it you have a set of refrigerant gauges, do you?

My uncle has gauges and he is in San Antionio. So I just left for 30 mins and came home, compressor and fan outside was COMPLETELY OFF, air handler in the house was stilling blowing. I dont know what to do now.

Both the indoor coil and outside coil have been cleaned throughly, within the last month. Inside coil was very very dirty.

 

[wreedlbz]

Have you check the contactor?

How do I check that?

 

[wreedlbz]

Cap was completely shot, replaced it and so far so good.

 

[wreedlbz]

well it ran for about 30 minutes and cut off again, the compressor and the fan stopped outside. im at a loss now, gonna call the home warranty company. The unit had been off for over 12 hours now so I dont think heat is a issue.