I am singing those AC Blues too

[Snotter]

It seems that a lot of sailors are having AC problems. I joined their ranks this weekend.

I have a 1980 Morgan 41 Out Island with two marine AC units on board: a 19000 BTU unit for the forward cabin and a 9000 BTU unit for the aft cabin. The two units are from the same maker and use the same kind of digital thermostat in both units. (I believe the company that made them are out of bussiness because I get a private residence when I call the phone # stamped on the name plate.) Neither unit incorporates reverse-cycle heating. Both units share a common raw-water pump which comes on if either unit's compressor comes on.

This weekend the compressor in the aft cabin quit coming on. The fan runs and the relays that trip the water pump and compressor closes, causing raw water to be pumped. However, the compressor does nothing. I opened up a metalic box that holds the circuit board and that contains 3 relays. The relays control the heating strip as well as the raw water pump and compressor. The starting capacitor, which has 4 connectors (3 of which have wires attached), is also mounted beside the circuit board in the metal box.

I shorted out the leads on the relay associated with the compressor to see if I could get the compressor to work while the raw-water pump was pumping. No sparks or anything which could indicate that the relay is good and that I should be looking else where for the problem.

Can anyone tell me how to trouble shoot this beast? I live in North AL away from Marine AC specialists. Will a regular HVAC technician be able to fix my unit?

 

[kloudie1]

That doesn’t sound too good.. if you have power to the compressor leads and the capacitor is good, sounds kinda like the compressor is gone .. .. A regular technician should be able to fix it since the only real difference is that the relay that would turn an outside condenser fan in a regular unit now turns on a water pump in this unit.. But getting one interested might be a problem.. Good news is the compressor is an off-the-shelf unit and can be replaced like a regular unit.. bad news is it is fairly expensive to do that.. If the unit is easily accessible, the technician won’t beat ya so bad with the bill! Try to get it opened up as much as possible for good access when ya call him.. and have the inside cooled off with the other unit so he can work it in the cool. (instead of his normal work in an attic!) Good Luck!

 

[Paul Mermelstein]

While I am not an AC specialist, I do know a little about working with electricity. First off, don't go shorting anything, especially around capacitors. This could injure or kill you. The best way is to use a Volt Meter (or combination VOM).

Start with the thermostat with the meter. Is it receiving input voltage? If so, start working downstream. Is it putting out voltage to the relay? If so, go the relay. Is the relay input circuit showing voltage from the thermostat? If so, does the relay trip? If so, is the part of the relay that is connected to the compressor showing output volts? If not, it is the relay or the contacts in the relay are corroded (this happens with relays all the time). If so, next go to the compressor to see if the same voltage is reaching it. If so, it most likely is either the connections, or the compressor motor.

Basically, be methodical and check for sufficient juice from beginning to end to find out where the problem resides. Then you can figure out the cure.

Good luck.

 

[Stu Jackson]

So, you left the important information out: Make and Model and Manufacturer. Why not tell what units? What's the big secret? Maybe, just maybe, someone would note it and say "Oh, yeah, all the Gunderson Model 345ABC's do that, just twist the thingie to the left 3 degrees and everything will work!" What's the big secret?

Read this --- How to Ask a ?:
http://forums.catalina.sailboatowners.com/showthread.php?t=101369

 

[Snotter]

So, you left the important information out: Make and Model and Manufacturer. Why not tell what units? What's the big secret? Maybe, just maybe, someone would note it and say "Oh, yeah, all the Gunderson Model 345ABC's do that, just twist the thingie to the left 3 degrees and everything will work!" What's the big secret?

Read this --- How to Ask a ?:
http://forums.catalina.sailboatowners.com/showthread.php?t=101369

The attached pictures are of my unit.

 

[Snotter]

Sorry about the attached files in the previous post.

Maybe two times is the charm.