Front A/C not working

[ilvtravln]

Have a Dometic Penguin front A/C, was add on unit, about 12 years old, seldom used. Fan will not come on nor the compressor, took the cover off the top the fan turns freely. Tried to get the plastic cover off the bottom, got 4 screws out and 2 plastic clips undone but could not get cover off, didn't want to force plastic cover anymore as I thought I might break it. Breaker was not tripped but turned it off and on anyhow. Any ideas what I might check next ? Thanks

[joebedford]

Have you checked for corrosion on the phone cable that connects the two a/cs? That what caused my front a/c to not work last year.