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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8769
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My central ac unit cools very well but sometimes when it

Customer Question

my central ac unit cools very well but sometimes when it turns off after it reaches the correct temp it don't want to come back on. usually after it sets for a while with the breaker off it will work good again soon as I turn breaker back on.
JA: Did you double-check the thermostat? And what about the unit's filters?
Customer: yes
JA: Do you plan on doing the work yourself?
Customer: maybe because I use to be a electrican and am very handy
JA: Anything else we should know to help you best?
Customer: I have already pulled off electric panel and checked breaker
Submitted: 3 months ago.
Category: HVAC
Expert:  Phil replied 3 months ago.

Hello, if it was a very hot day, and your AC is over 5 years old, it could have tripped its high pressure cut out switch when it went off.. Click here

That is basic maintenance that needs to be done regardless if it is the cause of the current problem.

We can go from there.

Customer: replied 3 months ago.
It doesn't trip off. Once it meets the temperature it cuts off. Just trying to determine what the issue could be
Expert:  Phil replied 3 months ago.

The ONLY things that will cause that phenomena are:

1. Dirty condenser coil and compressor over heating on the off cycle and tripping its internal heat sensitive over load.

click here for a photo of that switch buried inside the compressor (90% chance this is the case)

2. Dirty condenser coil causing the high pressure switch to open at roughly the same time the house gets to the set temperature.

Click here for some photo's of the typical high pressure cut out switch.

3. System slightly low on refrigerant, and tripping the low pressure cut out switch (happens on cooler days) 5% chance that is the case here.

.The solution is to clean the condenser. (see previous video link on how to do that)


We can go from here without any time limit until we have a full diagnosis or the the system is repaired.

So far the odds are in the 90% + range that the condenser coils is just dirty.


Stay in touch as needed. When you have all that you need please select the 'finish and rate your expert' link near the top of your page to close the question, I will appreciate it. Your positive rating is the only way the company pays me for my work, lacking that I work at a loss. Thanks!