Although you did not say if the compressor continues to run for a few more minutes, I would assume this is the case. Otherwise, post a comment here, there may be other issues.
These fan motors have an internal thermal shutdown device to prevent it from overheating and creating a house fire in the process. The time that it takes to make it stop makes me think it's probably related to overheating of the motor. Does it run any longer if it's a bit cooler outside?
If it is overheating, there could be several reasons (least expensive first):
* The fan motor may need oiling, especially if it hasn't been serviced in a while. If it takes too much power to spin the rotor, the windings will draw more current and will create more heat than the air can remove.Â See if you can get yourself a Zoomspout Oiler (
), which is filled with ConocoPhillips/Unocal 76 Turbine Oil - good for motors up to 5HP and lubricate around the shaft. A similar oil, something like "3 in 1" will do, too, I just like the Zoom's extending spout.Â The motor will likely have oil holes you can use or apply around the shaft and let it soak in. Apply from both sides of the shaft. The fan blades will have to be taken off and the motor taken off the bracket to get full access. WD40 may be needed to help with blades removal.
* The run capacitor may be bad and needs replacing. The capacitor may be dual, i.e. both start and run capacitors are in the same body, so you'll have to replace essentially both. Be sure to get an exact capacitance and max voltage value replacement capacitor. Slightly higher capacitance and/or voltage values are OK for the replacement but lower is not.
* The windings of the motor itself started shorting (internal insulation melting due to heat or physical damage). This is not reparable and the motor will need to be replaced. Be sure to find a suitable replacement or post a nameplate of the motor here, I'll help you locate one. Does not have to be the same brand, just the type, voltage and power rating and shaft diameter should match. Shaft length can be longer (can be shortened) but cannot be shorter than the original. For a 7 years old unit, chances are good to find an exact replacement. While you are at it, replace the capacitor(s) as well - they are not too expensive, you'll have to access them to disconnect them from the motor anyhow and at 7 years old they may be right at the point where they may start loosing capacitance or start shorting.
That's pretty much it in general terms. There may be other reasons, especially if there are more details to the issue you can share. Most important: what happens to the compressor when the fan stops. Does it cut off immediately (or, more accurately, do they both get shut off together) or does it continue to run until the pressure becomes too high and internal safeguards shut it off. If there's anything you want to add to the story, post a new comment here.
<strong>The power to the unit has to be shut off before you start!</strong>