Three days ago, right at the start of the heat wave on the Mid-Atlantic seaboard, my A/C stopped blowing cool air from the Heat Pump A/C system. A few days ago the air temperature was refreshing. The filter is new, the outdoor unit's fan works, the indoor unit's blower circulates fine and all of the registers and returns are clean and not blocked. Twice a year I vacuum the coils of the indoors unit and there is never even any dust. The outdoor unit is clear of any debris and all components by visual inspection look good. There are no abnormal noisesThe unit is a Heil and is about 9 years old.
As of 3 days ago, both copper pipes to and from the outdoor unit never get warm or cold. The condensate pump has nothing in it to pump out either.

About 3 years ago the outdoor fan stopped working due to a blown capacitor and at the time the tech said it could use a very small amount of refrigerant. Everything has worked fine up until 3 days ago.

Do home compressors have a low refrigerant cut-off circuit like automobiles do, so as not to run the system dry if it is low on oil/refrigerant?

Much abliged for any suggestions.

Brian L.

 

The thermostat has done its job and is calling for cooling. The power is on indoors and outdoors.

The compressor is not running. Inspect the electrical wiring for damage. With the power OFF, feel the compressor to see if it is HOT. If it is hot it is trying to run on occasion but failing to start or to stay running.

Turn it off for several hours and restart so you can observe and hear any compressor operation or attempted starts.

Let me know what you see. If it starts and runs for 5 to 15 minutes, the compressor may be cycling off on over-temperature safety. Most air conditioners do not have a low-pressure cutoff switch. They rely on the temperature safety switch to protect the compressor when refrigerant is lost (the compressor will heat up and shut down).