Hous AC - Dont get taken
#1
05-06-2012, 08:22 AM
House AC - Dont get taken
Most Central Air problems are simple to find and fix, if you know what to look for. I've had 4 calls on the properties I maintain and one involved freon. I expect maybe one more of the latter - topoff- all year.
First - the outside unit -Condenser- has a 'shutoff' box close by. Use it! If it doesnt it has its own CB in your house panel.
The furnace should have a switch next to it AND an interlock sw on the access panel. Use the switch till you are familiar with the wiring.
All controls including the thermostat and the outside unit work on 24 volt transformer power.
Here's something I wrote up on the TBird Forum:
forums.tccoa.com/showthread.php?t=136147
One of the calls, Friday was condenser fan 'frozen' After removing the 4 screws and carefully - wires in that conduit - pulling it up and turning it over I had to really give it a rap to break it loose. Then it spun freely. !!!! I didnt have any 3 in 1 with me but did have PS fluid, I dribbled a little oil where the shaft goes into bearing and 'spun it in'
First - the outside unit -Condenser- has a 'shutoff' box close by. Use it! If it doesnt it has its own CB in your house panel.
The furnace should have a switch next to it AND an interlock sw on the access panel. Use the switch till you are familiar with the wiring.
All controls including the thermostat and the outside unit work on 24 volt transformer power.
Here's something I wrote up on the TBird Forum:
forums.tccoa.com/showthread.php?t=136147
I published this elsewhere a few weeks ago.. should have done it here as well.
In hot weather like we're having now, it only SEEMS like your air conditioning is more likely to fail.
But lots of people are going to be more likely to pay for unnecessary repairs and replacement than usual because they can't bear the thought of losing their comfort.
Let me just say that this sort of weather will make membership in 'Angie's List' a bargain for those who have Air Conditioner problems. The reason being of course that those highly rated HVAC companies are less likely to do unnecessary work.
I've taken care of 40 plus older residential units for ten years and in that time exactly TWO AC systems have had to be replaced. Both were WELL over 20 years old.
It pays for you to know what your outside unit - the condenser - sounds like when it's running well.
Before a compressor fails it will start to make more noise/ get louder than usual, this may continue for days, weeks or even years. But do make a note of it. Chances of that compressor suddenly failing without warning -getting louder-a re very low.
There are two common failure parts in the condenser:
The power relay called a 'contactor' and the motor capacitor{s}. When the AC suddenly quits working, odds are over 90% it's one or the other at fault.
If the capacitor fails, the fan and/or the compressor tries to run but cant get started.
- Retail price of capacitor: $25-$35
Tip: When a capacitor goes it usually, due to overheat, balloons to some extent. The terminals are on little plastic cups.
Sight along the tops of the cups; if they are not level with each other, it is gone.
The important numbers on a cap are the UFD ratings. Typical on a residential 24,000 btu condenser is 35 for the compressor and 5 for the fan. 370 vac is the voltage rating. You can sub 440 vac in a pinch or +- 15% for the ufd rating but I dont advise it.
If the condensor fan motor itself fails, it will be relatively hard to turn. It should react like a pedestal fan. Easy to turn.
With thermostat in 'Off' position, try to turn the fan with a ruler or thin wood piece. If it's stiff or hard to turn, the bearings are bad.. actually usually 'dry' but it may not be worth having it lubricated. It has sealed bearing and must be disassembled to do it. {handy car guys can do it, of course. I lubed a dry-bearing fan motor 7 years ago and it's still running.}
In hot weather like we're having now, it only SEEMS like your air conditioning is more likely to fail.
But lots of people are going to be more likely to pay for unnecessary repairs and replacement than usual because they can't bear the thought of losing their comfort.
Let me just say that this sort of weather will make membership in 'Angie's List' a bargain for those who have Air Conditioner problems. The reason being of course that those highly rated HVAC companies are less likely to do unnecessary work.
I've taken care of 40 plus older residential units for ten years and in that time exactly TWO AC systems have had to be replaced. Both were WELL over 20 years old.
It pays for you to know what your outside unit - the condenser - sounds like when it's running well.
Before a compressor fails it will start to make more noise/ get louder than usual, this may continue for days, weeks or even years. But do make a note of it. Chances of that compressor suddenly failing without warning -getting louder-a re very low.
There are two common failure parts in the condenser:
The power relay called a 'contactor' and the motor capacitor{s}. When the AC suddenly quits working, odds are over 90% it's one or the other at fault.
If the capacitor fails, the fan and/or the compressor tries to run but cant get started.
- Retail price of capacitor: $25-$35
Tip: When a capacitor goes it usually, due to overheat, balloons to some extent. The terminals are on little plastic cups.
Sight along the tops of the cups; if they are not level with each other, it is gone.
The important numbers on a cap are the UFD ratings. Typical on a residential 24,000 btu condenser is 35 for the compressor and 5 for the fan. 370 vac is the voltage rating. You can sub 440 vac in a pinch or +- 15% for the ufd rating but I dont advise it.
If the condensor fan motor itself fails, it will be relatively hard to turn. It should react like a pedestal fan. Easy to turn.
With thermostat in 'Off' position, try to turn the fan with a ruler or thin wood piece. If it's stiff or hard to turn, the bearings are bad.. actually usually 'dry' but it may not be worth having it lubricated. It has sealed bearing and must be disassembled to do it. {handy car guys can do it, of course. I lubed a dry-bearing fan motor 7 years ago and it's still running.}
- Chances of fan motor failing electrically - almost zero. If it turns easily, and tries to start but wont.. chances of bad capacitor about 99%.
Retail price of fan motor: $150-$200.
If the outside unit does nothing at all, listen for a faint hum/buzz. That is the relay coil trying to start it. It is getting a signal from your thermostat. The A/C breaker may be tripped, in your inside box, the fuse {if any} in the outside box may be blown or the relay may be bad.
Cost - about 35 bucks. Most of them are the same. Difference is single or two pole switching.
- recommend you take a picture of it when you go for the replacement along with the make model and serial number of condenser unit. Swap one wire at a time.. with the power disabled at shutoff box.
- If there's no hum, check to see if you can turn the furnace blower on by changing thermostat switch from 'auto' to 'on', your furnace breaker may be tripped or there's an electrical problem in your furnace controls.
- make sure the control wire between condenser and wall isnt damaged by a stray weed whacker.
- If there is a hum, the compressor and fan do nothing, and your outside unit is getting power, that relay/contactor is probably bad. Common in ten year old or more.
Ice on lines to condenser unit. Means bad furnace airflow 90% or low refrigerant - not likely because it only happens at a certain point of low charge.
Change filter or your furnace blower is bad* or blocked air return registers.
If the outside lines have ice, that means your inside coil is a solid block of ice. Turn heat/cool OFF, furnace blower 'ON' and allow at least 2-3 hours for ice to melt. You will likely have water puddling around the furnace when that's done.
Use cheap furnace filters in cooling season. The wet inside coil gets those little bits of dust anyway. and the airflow is better.
* If the furnace blower doesnt run, turn t-stat fan sw to 'on', open the access door and reach into the blower and see that it spins freely. If it does, push in the interlock - you may have to wait a while, and see if the motor hums.
If it does, carefully reach around and spin blower. If it then runs, the problem is 80% chance the capacitor. I have seen inside motor run windings fail.
Retail price of fan motor: $150-$200.
If the outside unit does nothing at all, listen for a faint hum/buzz. That is the relay coil trying to start it. It is getting a signal from your thermostat. The A/C breaker may be tripped, in your inside box, the fuse {if any} in the outside box may be blown or the relay may be bad.
Cost - about 35 bucks. Most of them are the same. Difference is single or two pole switching.
- recommend you take a picture of it when you go for the replacement along with the make model and serial number of condenser unit. Swap one wire at a time.. with the power disabled at shutoff box.
- If there's no hum, check to see if you can turn the furnace blower on by changing thermostat switch from 'auto' to 'on', your furnace breaker may be tripped or there's an electrical problem in your furnace controls.
- make sure the control wire between condenser and wall isnt damaged by a stray weed whacker.
- If there is a hum, the compressor and fan do nothing, and your outside unit is getting power, that relay/contactor is probably bad. Common in ten year old or more.
Ice on lines to condenser unit. Means bad furnace airflow 90% or low refrigerant - not likely because it only happens at a certain point of low charge.
Change filter or your furnace blower is bad* or blocked air return registers.
If the outside lines have ice, that means your inside coil is a solid block of ice. Turn heat/cool OFF, furnace blower 'ON' and allow at least 2-3 hours for ice to melt. You will likely have water puddling around the furnace when that's done.
Use cheap furnace filters in cooling season. The wet inside coil gets those little bits of dust anyway. and the airflow is better.
* If the furnace blower doesnt run, turn t-stat fan sw to 'on', open the access door and reach into the blower and see that it spins freely. If it does, push in the interlock - you may have to wait a while, and see if the motor hums.
If it does, carefully reach around and spin blower. If it then runs, the problem is 80% chance the capacitor. I have seen inside motor run windings fail.
Last edited by pettyfog; 05-06-2012 at 08:47 AM. Reason: typo in title
#2
05-06-2012, 06:49 PM
Thanks for the good information, I'll be saving it for future use.
I've noticed an abundance of complete unit replacement over the last year or two after talking to friends. They've been trying to get us to replace our 10 year old unit for the last year or so, saying it's "on it's way out," but for the cost we just won't do it. Quoted around $10,000. It seems like most problems are simple enough to repair anyway. We're probably going to get serviced by someone else next time around.
I've noticed an abundance of complete unit replacement over the last year or two after talking to friends. They've been trying to get us to replace our 10 year old unit for the last year or so, saying it's "on it's way out," but for the cost we just won't do it. Quoted around $10,000. It seems like most problems are simple enough to repair anyway. We're probably going to get serviced by someone else next time around.
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