One of our Split type heat pumps quit working. it just refused to start and flashed some indicator leds on the display. I decided to have a look at the connections on the circuit board on the outside unit as this has been a source of problems in some of these units. I found that this heat pump suffered a similar fate to many a GT that is left outside. MICE!!
They got in through a tiny hole near the refrigeration lines and built a nest smack on top of the circuit board. It's quite a mess. There are wires and components chewed through and corrosion and filth all over the board. I'm going to try to fix it but it's a bit of a long shot. I do like a challenge though.
Here's some photos. The last picture is after washing the board with warm water. There is still a lot of crap stuck to it. Disposable gloves and a mask were mandatory! I've got it cleaned up now and there are a half dozen or so resistors and ceramic capacitors that need replacement. That is just what I can see at a glance. Fortunately the board is labelled with all the part values. The nest is made almost entirely of dog hair from our 2 standard poodles. My wife scatters it at the edges of the yard in an attempt to keep the deer away.