Gas and Oil Home Heating Furnaces - How to know if the ac has to be replaced?

Hi

- I have an 8 years old trane AC which has been working fine.

- A 8-10 days ago, the circuit that controls the air handler fan (blower) was replaced. The technitian checked the freon and said it was OK!.

- 2 days ago, the air handler started to freeze, and block the air flow. All fans, and units were working, and I actually noticed that the outside unit was working even though the termostat was not activating it ("cool on").

- So I called the technitian again and the guy tellsme that I have to replace the outside unit for 2200. Because the compresor was "leaking"

- After changing some setting con the ICM board the AC seems to be working fine, and I dont see any signs of rust or anything on the outside unit.

- Can someone answer how is posible that the compressor leaked all freon in a week, if it has been working for over a year without problems. Note that the technitian replace someting that has nothing to do with the freon system.?

Sorry for the lenght of the post.

Jose :confused:

Hi,

While it is feasible for this to have happened, I kinda doubt it. If your outside unit was engaged and running with t-stat "not calling for cooling", it is more likely your contactor was stuck/fused in the closed position, thus keeping the unit running continously, which would cause the evaporator coil (Inside coil) to freeze up. If this happens again, turn off t-stat and if the unit keeps running, turn off 240v power at the disconnect outside or the breaker. If the unit stops, wait 10 minutes and turn 240v power only back on. If the unit starts up and runs, turn off power again. If it stops again, the contactor is stuck.

You can remove side panel on outside unit, with ALL power off and look at refrigerant lines coming into compressor for oily film around connections and compressor itself. There will be oil if the compressor is leaking. Trace the large electrical wires from compressor back up to the larger electrical control (contactor). If you have an electrical meter, turn on 240v power only and check for 240volts at the two incoming wires at the contactor. Look for where they enter the unit and follow them to the contactor for incoming. If you have 240volts, then check the two outgoing wires going down to the compressor. Make sure t-stat is OFF. With t-stat off, you shouldn't have any power at the outgoing wires, if you have 240volts outgoing with t-stat off, your contactor coil at the back is closed shut. Replace the contactor. TURN off all power when replacing and only turn on when testing.

Write back if more info needed and keep us posted please on outcome. Take Care and Best Wishes.

CoolBreeze

Hi,

I re-read your post and wanted to add some to my reply. Did you make the change to the ICM board or the tech. and do you know what change was made? This problem could have been a miswired board and could also be a t-stat acting up. When the change was made to the board, did it stop the freezing and correct the problem of running w/o t-stat calling? Is all running ok now? If it ran ok for a week after original repair and is running ok now, it could be an intermittant problem.

Write back with this added info and we'll go from there. Take Care.


CoolBreeze

Hi

Thanks for your tips.

I opened the unit today, and the refrigerant circuit that is on the side of the unit (the condenser and valves i think are called) are all rusted and they have some oil on them, so I guess I have to replace them.

I also took a look to the compresor and the coils and they seem ok. Now, I don't have experience, tools and freon to replace this part of the sistem myself, so I was wondering if somebody knows how much could it cost to replace (labor + parts)

Jose

PD. The ICM was replaced by the tech.

Hi,

You stated a setting was changed on the ICM board and now everything is running fine in your earlier post. Who changed the setting and what was it changed from and changed to what? Is the unit still running ok? Is it turning on and off when called for? Is it still freezing up?

The coils have U-bends at the ends of the coil runs and they will rust as will other places. It depends on HOW rusted they are as to whether it's time to do something. They also sweat and can look oily, did you feel/smell the film on them to be sure it was oily freon and not dirty condensation?

I would get a qualified, reputable, certified contractor to give a second opinion. It could be a major replacement or a simple repair.

I would not replace a compressor in an 8-10 year old unit, if it was mine. I would change out the condensing unit and the evaporator coil, if feasible, for a matched/balanced set.

As a "guesstimate", depending on who does the work and where you're located and how busy they are and whether their honest and whether they're bonded, insured, certified, licensed and etc., etc., etc..... , you're looking at $1,000.00 - $1,500.00 just for the condenser changeout alone. You'll just have to get some second and third opinions, do your homework and check around. Don't jump at the first thing you're told, there are crooks in ALL industries.

I can't say whether you've been given an honest opinion on your unit by the tech. because I'm not there. I can say it doesn't sound exactly right and I would do some more homework. Write back if more help/info needed. Please keep us posted. Take Care and Best Wishes.

CoolBreeze