fan stops rotating and air gets hot

[Michelle]

A few weeks ago, I flipped the breakers in garage (the AC breaker is separate from these though) and within 24 hours of doing that, my AC fan on outside unit stopped rotating. After a lot of research online and help of step-son, we used volt meter to test lines going in to outside unit and literally did nothing mechanically and it began to work again. Then about week and half ago, same thing. That time, just turned all power to outside unit and switch for indoor thermostats off for couple of hours, flipped all back on and it worked fine...until yesterday. Fan not working and now unit is making horrible noises. PLEASE HELP. I cannot afford to have it serviced and am hoping to do it on my own.

[homeowners]

Just trying to break the troubleshooting down to smaller manageable steps:

First of, the flipping of the breaker(s) other than A/C that had no immediate effect would not be the reason for the A/C malfunctioning 24 hours later. You could, in theory, disconnect the circuit that was feeding the low voltage transformer for the control board. I have seen them wired to any number of unrelated circuit and therefore breakers. But cutting the power to the control board would definitely stop the A/C as well. If that didn't happen, you can just disregard that event.

The "horrible noises" from the outside unit - does it sound like metal on metal screeching or how else would you describe it?

What  make and model is your outside unit? Sorry I don't have a solution or even a good idea about the problem, definitely not at this point. We need to establish some basic facts first.

Post your response as a new comment in the form above and we'll go from there.  

[Anonymous]

Thank you for trying to help me.  You have no idea how much I appreciate it!!  I just looked and it is a Lennox Model 13ACD.  I bought my house new in November 2007.  I have a 2 story with upper and lower thermostats and have been told that the outside unit barely is large enough for size of house but given it was a new home and other homes have same units, assuming they are fine for house size.  (Homes built after these have larger outside units though).   I change my AC filters religiously usually every month, sometimes at 3 weeks but try to never go longer than 5 weeks.  However, I do not have a vehicle right now and have not been able to get new filters and the one upstairs is pretty dirty.  Tried to vacuum it but its still pretty gnarly.   Last night, I took the top off outside unit to check inside and there were a lot of spider webs and gunk like that but nothing that looked like it could be problem with not running.  The fins were pretty yucky though so cleaned them with kitchen brush and plain water very carefully.  The outer edges on many (like where edge of top piece fits over them) are kind of pushed in. As for the noise it started making yesterday, hard for me to actually describe but would say it kind of reminded me of the sound the garbage disposal in kitchen sink makes if spoon is down in drain and you do not know when you turn it on.

[homeowners]

Hi Michelle,

Let's go further down the list and separate benign issues from serious ones.

The dirty and/or bent fins of the outdoor coil is not a good sign and they do need to get cleaned (can be water hosed and straightened (there's a tool for that) if they are really bad. But they would not stop the fan or the compressor from spinning.

The noise you describe does sound pretty bad, I agree. The compressor is most likely making that noise. Here is a video with a Lennox 13ACD compressor rattling sound recorded (at 9 sec into the video), does it sound like yours?

If you let it run like this, does it run or does it stop at some point?

Have you looked at the evaporation coils inside? They are behind a panel on the air handler unit, usually above the furnace.  I am actually wondering if the the evaporation coils have freezed up at some point in the past. If the system is undersized as you suspect (which 13ACD is it, they range from 13ACD-018 to 13ACD-060) it might have been running continuously for a long time. If the filter had started to clog up at some point and restrict the air flow, it could have lead to freezing of the coils and subsequent overheating of the compressor. If left unchecked, the freezing can lead to a permanent damage to the compressor. Don't want to scare you, just trying to find a  plausible explanation for the sound that, unfortunately, does sound like a bad (or going bad) compressor.    

By the way, Lennox has a 5 year warranty. You are still within the 5 years - you should contact them and have a dealer come out a check it out.  1-800-9-LENNOX (1-800-953-6669)

[Anonymous]

Thank you for replying and helping me with this.  I had no experience/knowledge of any HVAC parts before this but have spent probably 20-30 hours educating myself via online resources.

How can I tell if the coils have been frozen in past as you mentioned?  Truth is, I am betting that is the case because I kept finding my thermostat settings being changed from "Auto" to "On" and when I would ask who did it, of course, nobody did.  It happened several times and thinking back, I want to say it happened around time of first incident but can't say for certain.  

From a lot of other posts/responses I have been reading, I also think it could be a fan capacitor issue but it is not swollen as a lot of people say they should be if bad.

Going back to first time it happened...I had friend try to use volt meter to see if it was getting power to outside unit and although I did not see myself, they said an arc shot out at them.  Later, I had my step-son come check and at first, it showed a really high reading coming out of the unit.  He did not  disconnect/connect anything but after a few minutes, I turned it on and it worked fine until last week.  

The exact model is 13ACD-036-230-02.  

If I call Lennox to come out, will they be able to tell me the problem with that being under warranty coverage?  Not sure what I tell them when I call to ensure warranty picks up tab.

[homeowners]

Hi Michelle,  it would be difficult to see signs of the coils freezing up at some point in the past because the ice has by now long thawed and the water has collected into the drip pan and have already drained away and evaporated. You may see some signs of recent water flood in the pan or around the suction line (pipe going back to the condenser unit outside). In other words, look for signs of water around the indoor air handler unit, especially in spots where water does not belong - sides of the cabinet, floor under the suction line, that sort of places.

I can't really be sure if freezing up is what happened here, just trying to spell out possibilities and tie together the symptoms you've described. At this point I think you really should have an HVAC tech come out and take a closer look at the system - there's only so much you can diagnose remotely.

Your unit is a 3-ton split system. I don't know the size of your house and the climate you live in but yes, it may be on a small side for a 2-story house in a warm climate. Once you get it fixed, you will do best by the A/C to help easing its heat load by closing shades on the sunny side or installing sun protection film on the southern windows, verify if attic insulation is adequate etc. Different story from the repair we're talking about here but will be important for going forward once you get it fixed.

As far as a warranty repair - due to the way Lennox (and, to be fair, most other vendors) handles labor charges on warranty service calls, the repair itself is never a zero dollar deal to the consumer. You are still looking at several hundred dollars for the two trips of the tech: to troubleshoot and ID the faulty part and then to return and install it. Still, if the compressor is bad (unfortunately, it sounds like it), just the part itself can run about $700, and if Lennox can pick up that part of the cost, it would already be worth a call.  

Good luck!

[Anonymous]

And again, thank you!  

Can you tell me how to correctly test the fan capacitor using a digital multimeter (Etek 10709 digital multimeter that I have not located a  user's manual either here or free online download of one)?  I read a few different options and tried finding a good You Tube video but really couldn't get the right/most accurate way to do so.  I no nada about multimeters or how to use them.  I would love for it to be the problem.  

I called my homebuilder (Lennar) since I didn't have any warranty paperwork with all my owner's paperwork I received at move in and was told warranty info is on the unit itself and to always contact people who did installation to find out if they have any paperwork or how to handle it.  

[Anonymous]

I had disconnected capacitor earlier today to try to test it but didn't really know how as explained in earlier reply I sent.  After not being able to handle much more of the humidity in here, I just reconnected original capacitor, turned power back on to unit and turned switch on inside for thermostats and waited 5 minutes and outside unit and fan are running without the noises made a few days ago.   Temp in house is about 91 right now so I don't want to overwork the unit either with it running presently.  I am going to put my thermostats on 82 to begin with and see if it goes down to that temp without it stopping again.  

Suggestions??

[homeowners]

 Hi Michelle, great news on your unit! I'm assuming it's actually cooling the house at this point - could not grasp that from your post. I hope it's true and you won't have to celebrate the 4th in a hot and humid house.

I have seen your question about the capacitor testing and will reply to it on its own page just to keep things in order here.

[Anonymous]

Well, I wish I had good news in response to your question but sadly, it is intermittent meaning the fan will stop after about 10 minutes but will start when prodded by placing long object in top of unit and moving fan blade.   My brother in law said as long as unit remained cool (even with fan not blowing), it would be fine to run and said to strap a fan to the outside of the unit and run it for when other fan stopped.  That did not sound right to me so just pulled the power to unit again.

[Anonymous]

***Further research on my end of trying to understand how all this HVAC system works to hopefully figure out the problem, led me to some really dirty air ducts.  I pulled the filters and shined light up in the opening and yuck does not even begin to explain my feelings.  No wonder my allergies are shot right now also.  So, now, I am about to start removing all the vent covers to clean those while debating if I want to try and vacuum out the ducts myself or pay a laborer I know to do it.  

[homeowners]

 If it starts with prodding, it's definitely an indication of the starter capacitor malfunction. That's one half of the dual capacitor you were asking about testing of (I just replied on the other page )