Portable air conditioner.

[paulca]

I have an old portable airconditioner unit.  About a year ago it failed.  I have already bought a new one, but I've been considering fixing the old one, it can't be that hard.

Symptoms are:

When the unit is powered the lights come on, the temp display reads normally, the fan runs, everything looks okay.  However when I switch the active cooling mode on, no matter what the temperature is set to, the actual compressor does not start.  There is no relay click, nothing, it just sits dumbly doing nothing.

These units get pretty hot inside when running, I'm wondering it this is a classic case of electrolytic capacitor failing or maybe just a failed/stuck relay for the compressor.

I suppose a first test would be to open it and connect the mains directly to the compressor (or just bypass the relay) and see if it runs.  if it does it comfirms it's a control failure and diagnose from there.  If it doesn't run then the compressor is toast. 

Any experience with these units on here?

[Armadillo]

You should visual if the condenser fan is running.
If its running, the relay to the comp is energized.
if so, those are capacitors start motors. Easy cake to check those ac cap. Otherwise the motor or comp is fried [double confirm ac voltage at terminal]

If relay not energized, then is either protection [freeze switch, short cycle timer switch, high pressure switch], you can check if these devices are close circuit [with power off].
if the high pressure switch is open, then safest and cheapest to bin it, otherwise you need a AC mechanics.