AC Help Please

[Pete]

Have an original factory Cuisair installation from 1976, 16K BTU, that decided it did not want to run today. Has run OK as recent as yesterday, but today no. Symptoms are the compressor attempts to start for one of two seconds, sounds weak doing it, then you hear a click as something trips and all stops. Have checked the charge and plenty of Freon. Expert advice on what needs replacing would be appreciated. Hopefully not the compressor. My sense is it is related to the "start booster" relay or capacitor, but I have no knowledge behind this guess.

Thanks,

Pete

 

[Pascal]

What trips? If the breaker chances are the compressor is done. If th breaker doesn't trip it couldn't be the capacitor. If you have another 16k on the boat with th same capacitor you could swap them

Could also be the high pressure switch if you don't have enough water flow. If you have one pumps for multiple units, undo the discharge hose from the coils and make sure there is flow. I ve had one where the water hose to one AC was clogged and high press switch woudl trip. Looking outside there was plenty of flow to the other 3

 

[tonytrakovich]

If you hear the motor trying to start, I would lean toward the capacitors or the start relay. There is a start cap and a run cap. The click that you hear after a while is the thermal overload mounted to the compressor. When the compressor tries to start and doesn't, it heats up and trips the thermal. I am not sure how to test a cap but a quick google search should help

 

[Reefgeorge]

When the capacitors are bad the motor draws too much current while the compressor locks up and trips the thermal sensor mounted next to the can. Replacing the bad capacitor(s) will fix this. If the compressor is going bad then this will not help but will give you the same results. If you have a clamp meter you can watch the compressor curent while it tries to start and if you get around the nameplate rating for locked rotor amps and then it goes to zero then you have one of these issues. A less likely cause can also be air or moisture in the refrigerant circuit causing the lock up. You can either measure the cap with a capable DVM or swap out with known good components. The overload sensor can also go bad but not as often. High or low refrigerant would not result in slow compressor rotation unless the charge was high enough to cause compressor slugging which is essentially hydro lock. In a system with a receiver and/or accumulator as in the case of modern day Cruisair units this would be a lot of extra gas.

George

 

[Boatsb]

replacce the capacitors. If that does not do it replace the unit.

 

[rustybucket]

Had this happen last year with a smaller unit. There were two capacitors and a start relay in the control box. For approx $150 I bought all three and replaced all of them. I realize this is not the most efficient way of doing repairs, but better than being out of service waiting on parts to ship when one didn't work. Also, access to the control box wasn't that fun, only wanted to make one round trip down in that hole

 

[Reefgeorge]

Sorry, I forgot to include the start relay as another cause along with the capacitors.

Crude test is to shake it. If it rattles, probably bad.

George

 

[Boatsb]

I think I paid about $8 for a cap last time. That $150 must have been nice ones. Gold plated?

 

[Reefgeorge]

Cost depends on if you buy Cruisair parts or the same parts on eBay not in a Cruisair inventory bag. You can get USA made high quality caps for $10ish each.

George

 

[rustybucket]

I think I paid about $8 for a cap last time. That $150 must have been nice ones. Gold plated?

Two caps and the relay, plus expedited shipping. Straight from the MFG, it was too hot to ask questions and save money

 

[rsmith]

Remember to discharge capacitors before touching terminals.

 

[Pete]

Thanks to all for the analysis and advice. The failing component was the run capacitor, 15 microfarads at 330 volts. A quick trip to the local AC parts store was all it took. That is except for me performing a procedure that Hatteras obviously envisioned a double jointed, anorexic, midget performing, due to access.

It could be my imagination, but the compressor actually sounds quieter than before, in fact extremely quiet. Anyone ever notice such a change in a similar capacitor replacement?

Pete

 

[Boatsb]

I always replace both.

 

[rustybucket]

Remember to discharge capacitors before touching terminals.

ssshhhh!!! that's half the fun, here catch this!

 

[rustybucket]

double jointed, anorexic, midget performing

Pete

I gotta get one of those as a boating buddy!! Especially since my 13yr old is growing so much!! Wonder if I could post an ad like that on craigslist. White Male seeking double jointed anorexic midget to go boating/fishing with. All expenses paid!

 

[Reefgeorge]

New capacitors will sometimes make a compressor run quieter.

George

 

[Glory]

40 year old compressor, sounds like you , and POs, have got your moneys worth.

 

[Pete]

Yes, but in this case and many others in life, more is good and lots more is even better. Three of the four AC compressors on the boat are the original Copeland reciprocating gems. The smallest, a 7K unit for the bow stateroom was replaced by a previous owner. Although I have no direct knowledge of the event, I replaced a similar unit on a 36 Convertible I owned long ago, as the heat side of these small systems could not handle a full charge of Freon and did not have high pressure cutoffs. Long story.

Also, I was told by a former Cruisair service technician that replacement reciprocating compressor are no longer available, so replacement is not as simple as it was a few years back.

So, whenever I am in the engine room the compressors are on my list to offer some kind words of encouragement. They are the only moving parts items down there that has not been replaced or rebuilt. Sort of the last men standing.

Pete

 

[Pete]

Scott, are you a source or do you know of a source I can use to get a spare 230 volt start relay that Cruisair used in the original "blue paint" units, other than Cruisair/Dometic?

Thanks,

Pete

 

[Boatsb]

Bring the old one to a motor and electrical supplier like Grainger or online there's mcm electronics and some others.

I have a few local distributors I use that have most of the parts in stock. Depending on your area you may have a wholesale hvac distributor or a Grainger that can work with you.