Central Air Conditioning Troubleshooting

Questions on how we spend our money and our time - consumer goods and services, home and vehicle, leisure and recreational activities
Post Reply
Topic Author
blackwhisker
Posts: 169
Joined: Thu Jul 05, 2018 9:32 pm

Central Air Conditioning Troubleshooting

Post by blackwhisker » Wed Jun 12, 2019 2:07 am

My AC stopped working in 100 degree weather. It will be about at least 5 days until I can get a repair man because they are all booked.

Is there any simple troubleshooting guide out there I can use on my own?

I can still hear the fan, but no cool air, only warm air comes out.

I think it might be a simple fix because a repair man fixed within a few minutes when it broke one year ago. But he acted as if he wasn't totally sure if he fixed it. He didn't tell me what exactly the problem was. He just told me I didn't need freon charged. I had a feeling he didn't want to tell me which part was fixed because it would be hard for him to justify to charge that much money.

Any troubleshooting suggestions would be greatly appreciated!

Thank you!

P.S. is there any relatively light-weight portable AC anyone can recommend? I would like to have a backup solution in case my central AC fails again in the future.

User avatar
mrspock
Posts: 355
Joined: Tue Feb 13, 2018 2:49 am
Location: Vulcan

Re: Central Air Conditioning Troubleshooting

Post by mrspock » Wed Jun 12, 2019 3:06 am

Go outside and see if the unit is turning on vs. your blower fan near your furnace. If the outside unit isn't turning on it could be as simple as swapping out the capacitor. You can go on Youtube and learn how to diagnose & replace this. Here's an OK guide I found as well: https://sansone-ac.com/how-to-tell-if-a ... or-is-bad/

This happened to me maybe a year ago, and I was able to swap it out in maybe an hour for 50 or 60 bucks. Getting a repair guy was a pain in the butt for similar reasons, so I just did it myself. I will say, please follow appropriate precautions when changing out the capacitor, you don't want to get zapped by one of these, so follow the instructions to dis-charge the old capacitor safely if you tackle this yourself.

Housedoc
Posts: 309
Joined: Thu May 24, 2018 4:25 pm
Location: Alabama

Re: Central Air Conditioning Troubleshooting

Post by Housedoc » Wed Jun 12, 2019 3:50 am

Also check the small wire that is normally taped to the suction, aka larger copper line. Animals chew on this wire. It supplies control voltage to the contactor. If neither the fan or compressor are running it's worth looking the wire over. Also you can try taking a small wooden dowel and give the fan blade a spin, if it tries to spin or does come up to speed start capacitor previously mentioned is 1st part to go after.

dominque
Posts: 10
Joined: Mon Mar 19, 2018 5:45 am

Re: Central Air Conditioning Troubleshooting

Post by dominque » Wed Jun 12, 2019 4:59 am

A friend of mine had a similar problem. His evaporative unit was in the attic and used an overflow pan beneath the unit. It was clogged and triggered off by a float switch. I've had the same problem in the past as well.

The only other thing that I would attempt is replacing the capacitor(s). Be sure and turn off all breakers and then discharge the capacitors before replacing. They store quite a bit of energy.

Call_Me_Op
Posts: 7282
Joined: Mon Sep 07, 2009 2:57 pm
Location: Milky Way

Re: Central Air Conditioning Troubleshooting

Post by Call_Me_Op » Wed Jun 12, 2019 5:31 am

Whenever my system has blown warm air, it has been because it was low on refrigerant. If the compressor is running and the fan is blowing warm air, it is possible that you have developed a refrigerant leak and are low on refrigerant as a result. There are other possibilities (like a really durty evaporator) but I have not experienced them.

That really stinks. I would call around like crazy to see if someone can stop by to check refrigerant status. Even if they do not have time to fix the leak right now, often adding some refrigerant can get you through until someone can come out to fix it.

Did your system stop working suddenly? That knowledge may help to narrow possibilities.
Best regards, -Op | | "In the middle of difficulty lies opportunity." Einstein

HomeStretch
Posts: 488
Joined: Thu Dec 27, 2018 3:06 pm

Re: Central Air Conditioning Troubleshooting

Post by HomeStretch » Wed Jun 12, 2019 5:57 am

If the compressor and air handler are both running and you are getting warm air blowing, my guess is your system needs refrigerant and a check for leaks.

If your system is old, it may be time to think about replacing it during the off-peak season.
blackwhisker wrote:
Wed Jun 12, 2019 2:07 am
I think it might be a simple fix because a repair man fixed within a few minutes when it broke one year ago. But he acted as if he wasn't totally sure if he fixed it. He didn't tell me what exactly the problem was. He just told me I didn't need freon charged. I had a feeling he didn't want to tell me which part was fixed because it would be hard for him to justify to charge that much money.

You need a new repair wo/man. It’s reasonable to expect a repair service to clearly explain the problem and the fix.
Last edited by HomeStretch on Wed Jun 12, 2019 7:05 am, edited 1 time in total.

User avatar
fire5soon
Posts: 559
Joined: Tue Feb 20, 2007 3:07 pm
Location: FL

Re: Central Air Conditioning Troubleshooting

Post by fire5soon » Wed Jun 12, 2019 6:00 am

The most common reason for the problem you describe is a bad capacitor. If you have a multimeter you can determine if the capacitor is bad pretty easily (especially one that can test capacitance). YouTube is your friend here. If the capacitor is bad then it's a super easy fix.

If you do mess with the capacitor remember that it can still hold a charge and might need to be discharged. Most folks just use a screwdriver. Again, YouTube has all this info.

Good luck!
A man is a success if he gets up in the morning and gets to bed at night, and in between he does what he wants to do. - Bob Dylan

dalbright
Posts: 120
Joined: Sun Oct 21, 2018 6:23 am

Re: Central Air Conditioning Troubleshooting

Post by dalbright » Wed Jun 12, 2019 6:30 am

blackwhisker wrote:
Wed Jun 12, 2019 2:07 am
My AC stopped working in 100 degree weather. It will be about at least 5 days until I can get a repair man because they are all booked.

Is there any simple troubleshooting guide out there I can use on my own?

I can still hear the fan, but no cool air, only warm air comes out.

I think it might be a simple fix because a repair man fixed within a few minutes when it broke one year ago. But he acted as if he wasn't totally sure if he fixed it. He didn't tell me what exactly the problem was. He just told me I didn't need freon charged. I had a feeling he didn't want to tell me which part was fixed because it would be hard for him to justify to charge that much money.

Any troubleshooting suggestions would be greatly appreciated!

Thank you!

P.S. is there any relatively light-weight portable AC anyone can recommend? I would like to have a backup solution in case my central AC fails again in the future.
You would have to get in there and take a look to give us more info to help you. Your unit may be flashing trouble codes, blinking light where u count the number of blinks and compare to what is shown on the inside of the door typically. This will help guide you to a possible cause. Warm air generally could mean as others have noted low refrigerant/a frozen coil. If your line is frozen over you can thaw it slowly by having the fan portion set on continuous (but have the AC off) and you may eventually regain some cooling ability but you cannot over-tax it. If you see the copper line is frozen its most likely a refrigerant issue which would need a repair person to add some in. But ultimately this would be a bandaid as it has to be leaking out somewhere. May be a good idea to check for a blocked condensate drain as well. Could be none of the above though depending on any codes flashing as well ;).

daheld
Posts: 499
Joined: Wed Sep 13, 2017 8:14 am

Re: Central Air Conditioning Troubleshooting

Post by daheld » Wed Jun 12, 2019 7:25 am

fire5soon wrote:
Wed Jun 12, 2019 6:00 am
The most common reason for the problem you describe is a bad capacitor. If you have a multimeter you can determine if the capacitor is bad pretty easily (especially one that can test capacitance). YouTube is your friend here. If the capacitor is bad then it's a super easy fix.

If you do mess with the capacitor remember that it can still hold a charge and might need to be discharged. Most folks just use a screwdriver. Again, YouTube has all this info.

Good luck!
^^THIS.

User avatar
queso
Posts: 701
Joined: Thu Jan 07, 2016 3:52 pm

Re: Central Air Conditioning Troubleshooting

Post by queso » Wed Jun 12, 2019 7:56 am

daheld wrote:
Wed Jun 12, 2019 7:25 am
fire5soon wrote:
Wed Jun 12, 2019 6:00 am
The most common reason for the problem you describe is a bad capacitor. If you have a multimeter you can determine if the capacitor is bad pretty easily (especially one that can test capacitance). YouTube is your friend here. If the capacitor is bad then it's a super easy fix.

If you do mess with the capacitor remember that it can still hold a charge and might need to be discharged. Most folks just use a screwdriver. Again, YouTube has all this info.

Good luck!
^^THIS.
+1000. I keep a spare capacitor on hand and built a discharger out of a cheap resistor I bought on Amazon and some spare wire (too chicken to use the screwdriver method). :happy

Topic Author
blackwhisker
Posts: 169
Joined: Thu Jul 05, 2018 9:32 pm

Re: Central Air Conditioning Troubleshooting

Post by blackwhisker » Wed Jun 12, 2019 8:27 am

I am the OP.

Thank you everyone for the helpful replies!!! They are very helpful.

I just turned the AC on and went outside to listen to the condenser, The condenser was humming instead of making a healthy working noise.

I don't think my repair man changed any capacitor last time.

I will watch some youtube videos to see if I can learn more about it.

User avatar
queso
Posts: 701
Joined: Thu Jan 07, 2016 3:52 pm

Re: Central Air Conditioning Troubleshooting

Post by queso » Wed Jun 12, 2019 8:57 am

blackwhisker wrote:
Wed Jun 12, 2019 8:27 am
I am the OP.

Thank you everyone for the helpful replies!!! They are very helpful.

I just turned the AC on and went outside to listen to the condenser, The condenser was humming instead of making a healthy working noise.

I don't think my repair man changed any capacitor last time.

I will watch some youtube videos to see if I can learn more about it.
A lot of times you can tell by just looking at it. Bad ones tend to look bloated/extruded at the end caps. Better to test with a multimeter anyway, but when mine fail I can usually tell just by looking at them.

User avatar
Watty
Posts: 16087
Joined: Wed Oct 10, 2007 3:55 pm

Re: Central Air Conditioning Troubleshooting

Post by Watty » Wed Jun 12, 2019 9:33 am

blackwhisker wrote:
Wed Jun 12, 2019 2:07 am
My AC stopped working in 100 degree weather. It will be about at least 5 days until I can get a repair man because they are all booked.
For future reference I have a deal with my HVAC company where they come out and service my AC and furnace in the spring and fall at the beginning of the heating and cooling season to check and service the system. I think it costs about $160 a year.

Part of the deal is that I get priority if I have a problem and I also get a discount on any needed repairs.

My AC went out two weeks ago on a 95 degree day, I called the problem in at about 8:00 PM on Memorial Day and it was fixed by about 3:00 PM the next day. About eight years ago I has a similar problem on the morning of the hottest day of the year and they were able to get it fixed in about five hours.

They are one of the bigger companies here so they have a lot of trucks in the field so they have a lot of people that can do the repairs so that helps the odds of me being able to get a service person quickly.

I live in a fairly mild area but we do occasionally get cold snaps and if the furnace was to go out during a cold snap there would be a risk that the pipes could freeze so being able to get that fixed quickly is also important.

By having the systems regularly serviced they may also run a bit more efficiently which might help offset at least part of the cost.

You might want to consider signing up for a similar program in your area.

User avatar
Sandtrap
Posts: 6756
Joined: Sat Nov 26, 2016 6:32 pm
Location: Hawaii😀 Northern AZ.😳 Retired.

Re: Central Air Conditioning Troubleshooting

Post by Sandtrap » Wed Jun 12, 2019 10:01 am

blackwhisker wrote:
Wed Jun 12, 2019 2:07 am
My AC stopped working in 100 degree weather. It will be about at least 5 days until I can get a repair man because they are all booked.

Is there any simple troubleshooting guide out there I can use on my own?

I can still hear the fan, but no cool air, only warm air comes out.

I think it might be a simple fix because a repair man fixed within a few minutes when it broke one year ago. But he acted as if he wasn't totally sure if he fixed it. He didn't tell me what exactly the problem was. He just told me I didn't need freon charged. I had a feeling he didn't want to tell me which part was fixed because it would be hard for him to justify to charge that much money.

Any troubleshooting suggestions would be greatly appreciated!

Thank you!

P.S. is there any relatively light-weight portable AC anyone can recommend? I would like to have a backup solution in case my central AC fails again in the future.
May be as simple as a thermostat, or a breaker trip on the outside condenser (either wall fuse or panel breaker), or a reset on the HVAC unit.
Download the repair manual and follow the troubleshooting guide.
j

sk2101
Posts: 231
Joined: Sun Jun 02, 2013 4:54 pm

Re: Central Air Conditioning Troubleshooting

Post by sk2101 » Wed Jun 12, 2019 10:05 am

mrspock wrote:
Wed Jun 12, 2019 3:06 am
Go outside and see if the unit is turning on vs. your blower fan near your furnace. If the outside unit isn't turning on it could be as simple as swapping out the capacitor. You can go on Youtube and learn how to diagnose & replace this. Here's an OK guide I found as well: https://sansone-ac.com/how-to-tell-if-a ... or-is-bad/

This happened to me maybe a year ago, and I was able to swap it out in maybe an hour for 50 or 60 bucks. Getting a repair guy was a pain in the butt for similar reasons, so I just did it myself. I will say, please follow appropriate precautions when changing out the capacitor, you don't want to get zapped by one of these, so follow the instructions to dis-charge the old capacitor safely if you tackle this yourself.
+1 I always keep a spare capacitor at hand.

Broken Man 1999
Posts: 2506
Joined: Wed Apr 08, 2015 11:31 am

Re: Central Air Conditioning Troubleshooting

Post by Broken Man 1999 » Wed Jun 12, 2019 10:10 am

OP, for temporary use you can buy a portable AC that vents through a window, unit has wheels so you just roll it to where you want it to be cool.

These portable AC units are sold at Lowe's, Home Depot,Best Buy, Amazon.....

I need to buy one myself as if the power is off, my generator isn't going to power my heat pumps. OTOH, a portable AC keeping one room cool would be easy to do with my generator.

Prices vary from $300 - $500 when I did a quick look at a couple of the sites mentioned above.

Good luck!

Broken Man 1999
“If I cannot drink Bourbon and smoke cigars in Heaven than I shall not go. " -Mark Twain

neilpilot
Posts: 2458
Joined: Fri Dec 04, 2015 1:46 pm
Location: Memphis area

Re: Central Air Conditioning Troubleshooting

Post by neilpilot » Wed Jun 12, 2019 11:00 am

Sandtrap wrote:
Wed Jun 12, 2019 10:01 am

May be as simple as a thermostat, or a breaker trip on the outside condenser (either wall fuse or panel breaker), or a reset on the HVAC unit.
Download the repair manual and follow the troubleshooting guide.
j
Of course none of the items you list are the problem, since the OP posted that I just turned the AC on and went outside to listen to the condenser, The condenser was humming instead of making a healthy working noise.".

What can't be determined from the OP's report is if the "humming" noise is coming from the compressor or the condenser fan. So it would be very helpful if, when the OP observed the outside unit the report indicates if the condenser fan actually running. I have 3 older AC units, and have in the past observed similar symptoms on 2.

In one case, the condenser fan was not running and the hum was from the compressor. The capacitor tested good, but the fan's motor had shorted out. I replaced the condenser fan's motor for about $60, and fixed the issue.

In the other case, the hum was from the fan motor and a capacitor solved that issue ($12).

User avatar
Sandtrap
Posts: 6756
Joined: Sat Nov 26, 2016 6:32 pm
Location: Hawaii😀 Northern AZ.😳 Retired.

Re: Central Air Conditioning Troubleshooting

Post by Sandtrap » Wed Jun 12, 2019 11:57 am

neilpilot wrote:
Wed Jun 12, 2019 11:00 am
Sandtrap wrote:
Wed Jun 12, 2019 10:01 am

May be as simple as a thermostat, or a breaker trip on the outside condenser (either wall fuse or panel breaker), or a reset on the HVAC unit.
Download the repair manual and follow the troubleshooting guide.
j
Of course none of the items you list are the problem, since the OP posted that I just turned the AC on and went outside to listen to the condenser, The condenser was humming instead of making a healthy working noise.".

What can't be determined from the OP's report is if the "humming" noise is coming from the compressor or the condenser fan. So it would be very helpful if, when the OP observed the outside unit the report indicates if the condenser fan actually running. I have 3 older AC units, and have in the past observed similar symptoms on 2.

In one case, the condenser fan was not running and the hum was from the compressor. The capacitor tested good, but the fan's motor had shorted out. I replaced the condenser fan's motor for about $60, and fixed the issue.

In the other case, the hum was from the fan motor and a capacitor solved that issue ($12).
Good points!

Topic Author
blackwhisker
Posts: 169
Joined: Thu Jul 05, 2018 9:32 pm

Re: Central Air Conditioning Troubleshooting

Post by blackwhisker » Wed Jun 12, 2019 4:16 pm

Again, thank you thank you everyone for the helpful replies!!!

Post Reply