Residential A/C troubleshooting?

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I support individuals in a 3 bedroom ranch home. Last year I reported to my supervisor and manager that the A/C was not cycling off. Fast forward to this year. Still has the same problem. I was outside recently and noticed condenser cooling fins completely clogged with grass and debris. I hosed them off until clean. Some plants (weeds) where growing too close to unit and I pulled them. It was a cool night and A/C finally cycled off.

I got my manager involved. We looked at the evaporator. It was newish looking and water drain was clean. I thought the drain was clogged since water was not coming out of it. I am thinking it just is not pulling a lot of water out of the air since A/C is not cooling well. I replaced the cleanable filter with a new paper one. Temperature of air coming out of the vents before and after cleaning fins outside is 60 degrees.

Our agency maintenance depart said the A/C was working fine. I am pretty sure they did not put gauges on it. They said it was not cycling off since it was hot outside.

My manager is reaching out to the landord. I do not expect much. The landlord tends to be slow to repair or maintain things. His A/C unit running most of the day continuously could become a more expensive problem if not taken care of. There is a lot of extra wear and tear on everything, plus extra electricity wasted.

I am looking for information to provide my manager on troubleshooting the A/C. My manager is less than 1/2 my age and does not have a lot of experience or time. Most of my experience is maintaining a household A/C over 20 years that has a professional checks yearly. Thanks!
 
The 60F temp isnt important.. what is the temp differential.

IE how hot is the inside air... vs the cooled air.

17-20F difference is pretty good.

But high humidity or attic ducting can quickly lower the temperature difference.
 
Did you take a look at the fins on the condenser inside the air handler?

I'd suspect that it is filled with dust also and will need to be cleaned.

You can use Tuff stuff and a fin brush, and rinse it carefully, or you can use the expensive AC cleaner stuff.

Obviously not 24 hours a day, but it is not uncommon for a properly sized system to run constantly for a few hours during peak heat of the day.

Mine runs for a few hours continuously daily during the heat of the day, then shuts off and runs normal cycles to keep the temp low.
 
Originally Posted By: Rand
The 60F temp isnt important.. what is the temp differential.

IE how hot is the inside air... vs the cooled air.

17-20F difference is pretty good.

But high humidity or attic ducting can quickly lower the temperature difference.


All I know is air from vents is 60F no matter what outside temp. On a hot day you have to run several fans to keep comfortable. We set the thermostat at 72. When it is hot outside inside temps will increase even though the A/C is continuously running. At night it gets closer to 72. I leave at 11pm at night and it will still be running.
 
Originally Posted By: JustinH
Did you take a look at the fins on the condenser inside the air handler?

I'd suspect that it is filled with dust also and will need to be cleaned.

You can use Tuff stuff and a fin brush, and rinse it carefully, or you can use the expensive AC cleaner stuff.

Obviously not 24 hours a day, but it is not uncommon for a properly sized system to run constantly for a few hours during peak heat of the day.

Mine runs for a few hours continuously daily during the heat of the day, then shuts off and runs normal cycles to keep the temp low.


I bought some of the expensive cleaner, but did not have access to the side that may be dirty. I did not want to do more harm than good. One of the residents has asthma. Did not want to spray chemicals, so I stopped there. At this point I have done all I can do. My shift is 3p-11p. A/C will run continuously the entire shift now that it is hot outside.
 
You didn't say what the inside temps are. 60 deg output is good if the inside temp is 85, not so good if the inside temp is 75 but not terrible. The air handler could be clogged or it could be the unit is just undersized. It sounds like you've done all you can but the air handler. A maintenance guy seeing 60 deg is going to say it's OK.
 
Originally Posted By: AZjeff
You didn't say what the inside temps are. 60 deg output is good if the inside temp is 85, not so good if the inside temp is 75 but not terrible. The air handler could be clogged or it could be the unit is just undersized. It sounds like you've done all you can but the air handler. A maintenance guy seeing 60 deg is going to say it's OK.


Thermostat will get to 74 when I arrive. If hot outside the inside temp is 75 or more. I am not sure since I work evening shift and am not there when it is 100 outside. Only late at night will it get closer to 72. The A/C unit is very small in size. I could see the property manager getting the cheapest unit. Where I live the A/C unit is twice the physical size and pretty much freezes you when running and cycles often.
 
When the condenser fins are clogged like that, it's not able to do its job which is to reject (transfer) heat to the atmosphere. As a result the head pressure increases, causing the compressor to work harder. This also results in diminished cooling capacity.

The evaporators job is to absorb heat from inside the structure and stay below the indoor dew point to remove moisture. It will not do either if IT is clogged.

To confirm, you need to get a look at the inlet face of the evaporator coil. You can rake the muck off with a stiff, bristle brush before using a coil cleaner. Be sure to use a non-acidic, indoor coil cleaner.
 
Originally Posted By: sleddriver
When the condenser fins are clogged like that, it's not able to do its job which is to reject (transfer) heat to the atmosphere. As a result the head pressure increases, causing the compressor to work harder. This also results in diminished cooling capacity.

The evaporators job is to absorb heat from inside the structure and stay below the indoor dew point to remove moisture. It will not do either if IT is clogged.

To confirm, you need to get a look at the inlet face of the evaporator coil. You can rake the muck off with a stiff, bristle brush before using a coil cleaner. Be sure to use a non-acidic, indoor coil cleaner.


It would be nice to clean the evaporator. I could not access the dirty side easily. I watched a lot of you tube videos and it looks like a Pro will need to remove it if it needs cleaning. When I am at work I am busy supporting people. I may have 5 minutes here and there to fix things. With the manager it was after a meeting on my own time removing the panel to get a look see. I could see the job was bigger than my skill level.

It is like the chicken and egg. The blower motor going 24/7 is going to potentially suck debris into the evaporator.

I had a Saturn with terrible A/C performance. It's evaporator was clogged and after cleaning it worked great. So I understand the concept, but house unit is harder to get to.
 
On residential units, check if the running capacitor is up to the capacitance rating requirement.
Sometimes, capacitor does not bulge yet but it only has 1 to 2 uf.
There are usually 2 running capacitor, one for the condenser fan and one for the compressor.
Also, there is start capacitor also.
AC mechanics usually measure those when they do the yearly maintenance and also the pressure to make sure that there is no leaks.

The capacitor needs to be checked once a year at the beginning of the season which is usually spring, at least, that is my experience here in TX. Of course, cleaning will help maintained it.
 
Last edited:
Originally Posted By: JMJNet
On residential units, check if the running capacitor is up to the capacitance rating requirement.
Sometimes, capacitor does not bulge yet but it only has 1 to 2 uf.
There are usually 2 running capacitor, one for the condenser fan and one for the compressor.
Also, there is start capacitor also.
AC mechanics usually measure those when they do the yearly maintenance and also the pressure to make sure that there is no leaks.

The capacitor needs to be checked once a year at the beginning of the season which is usually spring, at least, that is my experience here in TX. Of course, cleaning will help maintained it.


The capacitor is a new one. I thought they just checked the pressure. I also read an under performing compressor could be the problem. Will report all the info given to my manager in a concise way. It looks like a pro who knows what he is doing is the ultimate answer. I can hose the condenser cooling fins monthly like I do at home.
 
Have the ducting inspected thoroughly. It's not uncommon for ducts to disconnect from the plenum or registers. I had a fresh air return duct slip halfway off the grill in my attic when the house was only 5 years old. It had a 3" gap which was drawing in hot attic air and causing a significant drop in output air temp. I also had to replace several sections of duct insulation after the outer plastic dried out and split open exposing the ducts.
 
If the unit is so dirty, but can still maintain 74-75F temps inside, then I don't see a reason to replace or that it is faulty. Just to clarify, is that the hottest it gets inside?

In any case, The unit and the area around it needs to be properly cleaned up. If the system is still underpinning after that, an HVAC pro needs to diagnose the system.
 
They make wands that spray water or air at a near 90* angle for flushing/cleaning hard to get to evaporators and condensers.
 
Originally Posted By: KrisZ
If the unit is so dirty, but can still maintain 74-75F temps inside, then I don't see a reason to replace or that it is faulty. Just to clarify, is that the hottest it gets inside?

In any case, The unit and the area around it needs to be properly cleaned up. If the system is still underpinning after that, an HVAC pro needs to diagnose the system.


So Sunday it was 73 at times. If you opened the door briefly it would go to 74. With 4 fans running it was OK. The back bedrooms were hotter, but made sure ceiling fans were working. I did notice the condenser cooling fins were getting full of grass clipping, so hosed them out again. Temp at vents was 60 or a little higher when testing. Outside temps was 92 when I arrived. A/C ran 8 hours straight. When I finished shift at 11pm thermostat said 72. This week we have 4 days in a row of over 100 degrees. Not sure how it will do and my Manager just went on vacation the rest of the week. It seems an HVAC pro needs to diagnose the system. I did all I can do to make that happen at this point.
 
take the top/fan off and wash out the condenser from the inside.
you might be surprised at what comes out.
the stuff you may only drive in deeper by washing from the outside.
 
I had a water spray set up that put a mist on the condenser coil from the outside. Worked great but I was using soft water and after a few years the salt ate up the aluminum.....
27.gif


But it really boosted the output of the old unit.
 
Originally Posted By: MONKEYMAN
So Sunday it was 73 at times. If you opened the door briefly it would go to 74. With 4 fans running it was OK. The back bedrooms were hotter, but made sure ceiling fans were working. I did notice the condenser cooling fins were getting full of grass clipping, so hosed them out again. Temp at vents was 60 or a little higher when testing. Outside temps was 92 when I arrived. A/C ran 8 hours straight. When I finished shift at 11pm thermostat said 72. This week we have 4 days in a row of over 100 degrees. Not sure how it will do and my Manager just went on vacation the rest of the week. It seems an HVAC pro needs to diagnose the system. I did all I can do to make that happen at this point.
Indoor humidity?
 
Before and After first cleaning:




As you can see I made some progress. Did not affect cooling one bit. Did allow A/C to cycle off when it was cool enough outside. This is a supported environment which means I need to let the Manager and Property Manager do the next step. My job is not A/C maintenance. I am trying get the ball rolling at resolving what I see as an issue.
 
Originally Posted By: sleddriver
Indoor humidity?


Not sure. I suppose I could take my hydrometer over to measure it, but not sure what that would prove? The drain from the evaporator is a slow drip. It does not seem to be pulling much moisture out of the house. This is humid Missouri. It is not like we do not have humidity.

Speaking of humidity, on the way home from that shift it rained. No it poured. Could hardly see the road on my way home. Cars had to pull off the Interstate it was that bad.
 
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