Have a combo AC/heat unit (electric).

The thermostat is a Honeywell 8195.

The AC randomly either works or it doesn't. Seems to depend on the day.

Once it works during a particular day it will usually reliably cycle on and off as needed for the entire day. If it doesn't work immediately at the beginning of the day it may start later on and then it works OK for the rest of the day (or it may not).

Turning the thermostat off and then on does not seem to make any difference.

VERY occasionally the circuit breaker on the unit trips but this is not the problem because it sometimes works and sometimes doesn't work with no resetting of the circuit breaker on the unit.

Wow!! What a pain! The only thing I can think of to do is wait until the unit is not working and starting at the A/C contactor coil check for voltage. If the common has voltage and the condenser wire doesn't, then I would think a faulty t-stat. No voltage, check the wires coming into the t-stat. If no voltage, then the transformer might be bad. Then you need to check the lines into and out of the transformer. At some point electricity is not present when it should be. That's caused by a faulty component or a break in the circuit. Intermittant power loss could be a loose wire, but I think a component is bad. Good luck with it.

Thank you for your response.

Two more things. The fan in the home comes on all the time. Also, the fan on the unit is running. That means that at least the circuits for those items have voltage from the thermostat. And, the thermostat was replaced only about 2-3 years ago. Would it go out that quickly (really a stupid question because things break down in even short periods of time).

Does this mean it is more likely to be a bad thermostat or something in the actual unit?

Quote:

---

Originally Posted by westnlas

Wow !!! What a pain !! The only thing I can think of to do is wait until the unit is not working and starting at the A/C contactor coil check for voltage. If the common has voltage and the condensor wire doesn't, then I would think a faulty t-stat. No voltage, check the wires coming into the t-stat. If no voltage, then the transformer might be bad. Then you need to check the lines into and out of the transformer. At some point electricity is not present when it should be. That's caused by a faulty component or a break in the circuit. Intermittant power loss could be a loose wire, but I think a component is bad. Good luck with it.

---

I am not an air conditioning tech, but a retired carpenter who spent his life repairing every tool and piece of equipment I ever owned, because I found that mechanics aren't dependent on my things working, but rather if they aren't. If the fans work, then the problem is within the compressor. Most of them have internal switches that will shut them down if there is a problem with the refrigerant. It sounds like yours might be low and the compressor is reacting to that. When it does start, does it get cold quickly? The only way to test the unit is with a set of pressure gauges that read the low (intake) and high (out put) sides of the unit. The oil that lubricates the compressor is in the freon itself. Low freon means low lubrication. This is something that most of us can't do ourselves. We can't buy the freon and the gauges that you need to tell when the level is correct are very expensive. I think you are probably going to need to get a service tech to look at it.

The oil that lubricates the compressor is in the freon itself. Low freon means low lubrication

A small amount of oil mist circulates in the system otherwise all oil is in the sump of the compressor.

Wayne444- More then likely if you have a programmable thermostate then there lies your problem, it don't matter if you had replaced it yesterday , it can be bad today. Check and see if the thermostate is set at the time of day that it comes on and works right. These type of thermostates give people a lot of trouble all the time. I do believe that you will find this to be your trouble, if you have a tech. to come out have him to do some checking and find out if there is a short some where that is messing up the thermostate. & messing up the printed circuit. :: Good Luck & GOD BLESS :: F.B.E.