Tiana: AC not turning off

There was a power outage in the neighborhood and ever since the power came back on, the AC no longer stops.

For example, if I set the thermostat at 75º, the AC runs smoothly until it cools to 75º, then I hear the thermostat clicking as to send the signal to the AC unit to stop, but the AC keeps running and from that point the lines in the AC unit start to form ice.

For as long as the temperature in the house is higher than the temperature I set in the thermostat, the lines doesn't freeze. They only start to form ice once the house reaches the temperature set in the thermostat.

I bought a foaming cleaning spray and I cleaned up the coils twice. I also removed all the dry leafs gathered inside the AC unit. It is very clean but the lines still freeze.

I am trying to figure what could have gone wrong when the power came back on because ever since the AC is not able to respond to the signal received from the thermostat to turn off.

I also bought and installed a new thermostat and the AC behaves the same.

Thank you in advance for your feedback!

 

Have you turned the thermostat to the "off" position? What happens?

 

The AC keeps running. Almost like there is no communication between the thermostat and the AC unit. But the unit sill perceives the temperature I set on the thermostat as the lines only start to freeze after the house reaches the temperature I set on the thermostat.

 

Also, it seems like something in the unit does turn off when the thermostat sends the signal to turn off. I am not familiar how the components in the unit work, but is like, supposedly, there are two things that make noise when the whole unit operates.

One is about 80% louder than the other one. The less noisy one does turn off. The louder one keeps working and cooling the house. But it looks like the less loud device is what "conditions" the lines because when it stops, the lines start to freeze. Does it make sense?

 

I just read another thread and I think I am facing the same issue. My *contactor* probably doesn't pop up. How do I locate the contactor? How does it looks like? Would some WD 40 make it work a little longer if I manage to pop it up if I also hit it with a screwdriver as the other person did?

 

the thin wire will lead to it,don't touch with power on. most times they are no good after a power spike.replace with same and make sure both units run at once as it's not good if they don't.

 

I turned the breakers off and removed the cover of the unit. It is not a split unit.
I do not let it run continually. Once it cools the house I run outside and turn the breakers off, then on again when it's time to cool.

But I have no idea what wire to look for so I could locate the contactor. I will try to post a photo.

 

 

Please help me locate the contactor if it is visible in the photo below.

 

Is this a self contained unit outside the house? What I am seeing is an air handler with an A coil and heat strips. Does this unit run continually or the one outside??? Or is this outside as well???

 

This is the only unit. It is outside. The photo only shows half view from the top. I was told to look for the thin wire, so I only took a close up of this side. I figured the contactor must be here somewhere?!

Being the only unit, this is the one that runs continually.

I'll take the ladder and will try to take a photo of the whole unit from above.

 

This is the unit.

 

View from the top

 

This should be it..... red circle

 

Thank you so much! I'll try to see what doesn't pop up tomorrow in day light. Hopefully I'll be able to fix it.

 

Only now I was able to look into it and yes, the contactor release button was stuck. I sprayed a little bit of WD 40 on it and I pushed it froward with the tip of the screwdriver. It popped out right away.

I turned the breakers and the AC back on, and once the house reached the temperature set on the thermostat, it popped out on it's on. The entire unit shut off as it is supposed to.

However, I can't even be glad. Tired of having to deal with everything. Life is sour and I'm tired of making lemonades. Thanks so much for sharing your knowledge!

 

Make sure you replace the contractor. Just freeing the contractors up is not the remedy. It will weld it self shut again.

 

I will call the electric company, maybe they will be willing to replace it since it went bad right after the power outage. If they won't, I'll be looking into purchasing one. I looked how the wiring is done, if I take a few pictures of the wiring set up I should be able to replace it myself.

How much do they cost and where I could purchase it from?

 

Buy it online and they should cost no more than $50 retail.

 

Tiana, if you search Google you will find a contactor for a very reasonable price...under 50 bucks.

 

Please help if you have the knowledge. Last night the AC unit stopped cooling. Both motors are running and there are no icy ducts. No ice is it an indication that a lack of freon in not the issue, am I right?

It is an old AC unit but had the contactor replaced last year. At that time I had the capacitors tested and they were both low. The AC resumed normal function after the contactor was replaced and I ordered new capacitors to have on hand.

Now that the AC stopped cooling I went outside and I replaced both capacitors with the new ones. I'm still back to square one; both motors running, fan blowing but no cool air.

The coils don't look dirty, maybe a bit dusty here and there. I am about to wash them anyway but don't think they are the culprit. The unit is fairly clean on the inside and not a bit of ice on any lines.

Any idea why did the unit stop blowing cool air? Thanks in advance!

PS - I replied to the old post instead of starting a new thread because I have previously posted pictures of the unit.

 

You have a blower motor under the electric heat strips, a condenser fan motor and a compressor on that unit. Are all 3 running?

Did you connect blue to Herm, 2 yellow wires to Com and a brown wire to Fan on the dual cap by the compressor?

Electric heat strips will always have power unless the breaker(s) or service disconnect is off. Be careful.

 

Thanks for your feedback. Yes, I turned off the breakers. When I changed the capacitors I un-hooked and hooked one wire at a time, exactly the way they were. I also paid attention to the markings on the capacitors, I am 100% sure I've done correctly.

I was not aware three things have to be running. The blower motor underneath the coils is running and the fan is running. I have to figure which one is the compressor.

I just washed the coils, cleaned up all the leaves and made sure the drain pipe is unclogged. It made no difference. That means the compressor might not be running? Could you advice where is it located?

Update: I think I located the compressor; is it the large, black unit located in the front left compartment next to the fan? How can I tell if it's running? By listening to the sound it is hard to tell because the fan blower is either too loud or the compressor might not be working. If it is the compressor, can they usually be fixed?

 

Yes that is your compressor. Is the suction line (highlighted blue) cold and "sweating"?



I would turn off power put on some safety glasses and remove the cover over the compressor terminals to inspect for burned wires if the capacitor is good and correctly wired.

 

I'm going to check right now. I just turned on the unit, can I touch the suction line while the unit is running?

On a side note, I now understand how the AC functions.

Sadly the suction line is not cold. I turned off the breakers and will now check for burned wires.

 

I was not able to push in the two safety plastic "pins" so I could remove the cover over the compressor terminals with one hand. It is dark and had to hold the flashlight with the other hand. I will have to leave it for tomorrow.

I appreciate your help! At least I know what stopped working. Maybe I should have changed the capacitors much earlier. Crying over spilled milk....

 

Yes, it's been one loose wire. I didn't fix it myself because that's just the way it worked out. I called an AC repairman yesterday on the spot. He was supposed to come over today to let me know what was wrong and to give me an estimate. In the meanwhile we figured it's been the compressor. When he came today he hooked back the wire right away and the compressor resumed working. He charged me $100. Everybody has to live. Now off to figure what I could sell on craigslist to make ends meet. Thank you so much for your help!

 

Was the loose wire the blue wire to your capacitor?

 

It's been the black wire to the compressor. It was just hanging, he pulled the wires by hand before removing the cover and the black wire came loose.

Does the black wire point to some damage in particular? I was just wondering how much would cost a new compressor.

I have been told that once a wire blows, it causes some type of damage into the compressor and the wire might blow again in about three months. Ultimately, he said, you are left with no more terminal to keep re-attaching the wire. He did say this could have been avoided if I would have changed the capacitor before the black wire blew.

However, the compressor it's been running louder for at least six months prior and now keeps running loud even though it has a new capacitor so it must be something else also 'crying' on the inside.

 

I have had bad luck trying to install a squeeze on slip connecter for compressor terminals. They melt over time. I use compressor terminal repair kits for reliable operation. If you replace it before your temporary repair burns off again it would be more likely to give you reliable operation.

 

I am a little bit confused. The QwickLug connector is exactly what he used. I am referring strictly to the black coated connector with the golden screw. The terminal coming from the compressor was corroded. He first squeezed the wires from the black cable in a metal 'housing', then he inserted the wire housing into the connector and he pushed it over the compressor's corroded terminal, then tightened the screw.

I am wondering if the corroded terminal coming from the compressor should be also insulated/reinforced before inserting it into the connector?

Also, he only fixed the loose wire. Would it be advisable/safer to re-connect all three wires with the terminal repair kit?

I looked up the kit, it cost about $25. I will wait for your feedback but I think I might be safer if I fix all three wires with the kit.

 

I clean the compressor terminal with a small wire brush and sometimes a wire brush attachment for my drill and only replace damaged connectors.

 

OK, I will leave it and hope for the best. Thank you Houston204!

 

The yellow wire to the compressor blew yesterday during the storm. I am looking into ordering the QwikLug kit online and re-connect it myself. However, I see the kit comes in four sizes; could somebody advise which model should I order? Thank you!

Update - I'm not sure what gauge is the wire, therefore I'll order the 10.

And by the way, I found out what caused the black wire to blow last year. About two feet up from the compressor there is a crack in the wire insulation. You can see the actual wire through the plastic. Yesterday during the storm it might have made contact with a drop of rain but since it is secured with the QwigLug terminal the compressor might have blown the yellow wire instead. Either way, I insulated the crack of the black wire over and over with electric tape. Now to re-secure the yellow and hopefully have AC again....

 

If you see any oil around this blown terminal it may be more than a connection kit this time.

I turn off power , isolate the wires from the compressor and get an ohm reading from each terminal to ground the measure across the terminals (start to run, start to common, and run to common) before installing a terminal kit.

 

A quick reply. I haven't seen any oil as far as I remember. The fan is working this time without the yellow wire but no cold air. The terminal is also very clean (silvery and intact), no rust, no damage. Just the ring terminal on the wire is damaged. I will look closely later today for any trace of oil. Thank you for your feedback!

 

It sounds like you only need the repair kit.

Blown terminals do not look the way that you have described.
They look more like this...

 

Attached are two photos of the terminals (one with the serial# in case I will need it at a later time). The kit should arrive on Saturday, I hope very much that it will get the compressor running properly again.

For informational purposes, may I ask from what AC model you posted the picture, Houston204? It looks almost new to me.

 

It has been many years since I took that photo of a rooftop unit at a club in Houston.
I suspect that it was caused by someone adding too much refrigerant.

 

The kit arrived today and the AC runs cold air! Thank God and so grateful for this forum and for the people wiling to share their knowledge. God bless!