Ok guys, you fixed my upstairs unit now...
I have a 4 ton heat pump down stairs. Unit has supplemental strip heating.
My outside unit will not cut off without using the outside disconnect. Inside (evaporator) fan is cycling as expected. When my inside temp (cooling) reaches temperature setting the evaporator fan cuts off. When this happens you can hear (through the air return) what I guess is freon traveling through the evaporator (sounds like water running upstairs). When I try to turn the unit off using the thermostat's cool, off, heat switch, the flowing sound quits (condensor unit still running) and I hear a slight low pitch buzzing or groan noise through the return. Unit has a Honeywell Thermostat, I'm not sure of the model. It is the rectangular unit with settings for Cool, Off, Heat, EM / Auto, On and side switch for setting temp.
Let me know what you think I should check!

 

Check and see if the contactor in the outside unit is stuck closed

Pull R off of tstat and see if the out door unit shuts off or not
get back to us.

ED

 

Thanks for the prompt response. I'll do it when I get home this evening and post back!

 

Don't let it continue to run like this or you could damage the outdoor unit. Like Ed said it's probably the contactor is stuck.

 

Well I pulled off the R wire and the Condensor did not shut off. I pulled the disconnect and left everything off for a few minutes. I reconnected the wire and powered up the condensor and all is working correctly now (through the night anyway). I guess it had a gremlin in it!
Correct me if I'm wrong, but I suppose the contact block was hung. I'll keep an eye on it for a while.