I have a mid 70's Marine Air unit in my boat. I thought it was not cooling as well as it should and had a tech come out and put some freon in all 3 units. One of my units is now cold and sweating on top of the compressor.  The other units are running warm but not hot. I took these temps. Room temp 77, vent air 56, water temp 70, top of compressor 52/bottom 66. The unit was not sweating until after the freon was added. I also clean the condensor coils on the unit with a 10% acid solution using a bilge pump and a bucket. Discharge air temps improved but compressor still cold and sweating. Will long term use in a overcharged state cause damage? Thanks

Doug~

I posted the above from my phone yesterday so my typing was not great…I have edited it a bit, but I'd also like to add….

From your TD (temp differential) figures (21 degrees) it also looks like you have a restricted air flow issue that may have caused your tech to overcharge the system to keep the low side pressure above freezing the coil…

If the low side pressure is below 58 psi with R-22, the coil will be below 32 degrees and freeze the humidity in the air passing across it…This then blocks more air flow & compounds the problem…

I would check first your air filters…Then get back to me with the size of the unit & the duct/grill sizes installed…

We want the TD to be withing the 15 to 18 degree range…If it more than 18 degrees it tells me that the unit is not picking up enough heat…IE: Lack or Loss of air flow…

Steve~