During the summer months, older AC units to homes can be challenged from the high temperatures. It is true that one-year usage equals seven years of an AC life and that most AC units start to fail between 7-10 years after installation.
There are a lot of components that can fail and be costly, but it is the compressor that is a key determining factor when deciding to buy a new AC unit for your home that can cost between $5-8,000. If the compressor fails (and you may not know it) the cost to replace it runs from $2000-3000. This is when most homeowners will buy a new AC system because everything will be new, not just the compressor. With special tools, the compressor can be tested for effectiveness by testing its insulation thickness and it takes less than a few minutes. A compressor that is failing or did fail will show thin insulation thickness.
Like many homes, I have central heating and AC. My unit is 8 years old, so I know I have been lucky as many fail before this. The only repair done was for a $700 fan. Most AC units have two such fan motors. The only symptom was that the AC unit was working fine when activated BUT no air was being felt out of the vents in the house. The compressor fan (unit is outside of home) was working, but it was the internal Air Handler Fan that failed. So, the cool air being produced was not being pushed into the home. The fix was easy assuming you can find the correct part and the fan cost around $200 or so. Basically, it was access and removing the old one held on by a few bolts and disconnecting it (just unclip it) and then installing the new one. The AC guy would charge around $700 do it, which included labor,
That was two years ago, more recently, the AC unit began to do two things that were concerning:
1. It was unable in high heat days to drop the temp you set it to. For example, setting the thermostat to 75 when inside the home was 80. The unit could not do it and would stop after reaching just 78.
2. The unit simply would not turn on again after reaching 78 until a few hours had passed.
3. At times, when it did activate, only warm air would blow for some time until cooler air prevailed.
After reading many things online about this, I was thinking the time for a new AC was now. That the compressor was going bad and unable to produce the cool air or that the AC system had a leak, and it was low on freon gas causing it fail. AC systems are closed, meaning, the freon gas used in them never depletes or is used up UNLESS there is a leak in the system. The gas is compressed by the compressor that produces the colder air.
I called the AC guy and he came out. He ran a compressor check and it was healthy. He checked for leaks and there were none. He some electrical checks for power supply and that was fine. At that point, he stated it is a clogged drain pipe.
This drain pipe usually is a white PVC pipe from the outside AC unit and can be any length. As the AC runs, water is created and should drain into a pan. A flow switch opens when it reaches a filled status and drains out onto the ground. Over time, this drain pipe becomes clogged with debris.
As a safety mechanism, if the drain become clogged and the water flow out is blocked, the AC unit will shut down until the water drains out. In my case, the line was partially blocked enough to shut it down and after a few hours, it drained. The key indication to a user is that when the unit shuts down, the thermostat will go blank UNLESS the thermostat uses an internal battery for power. In this case, the thermostat will show the inside\outside temp. This was my situation. So, I did not think it was related to the drainpipe.
To repair it, the AC guy brought a shop vac that sucks out water (they cost $50 or more), placed the hose over the end of the drainpipe and turned it on for 10-15 minutes. I had not done this in years (you should do this once every few months) and the amount of goo that was sucked out was shocking.
That was it! Of course, this was an expensive lesson at $250. I will invest in a shop vac for sure now.