HVAC issue

S

sarbog

Member
Aug 22, 2008
135
Emerald Isle NC
Boat Info
'05 340 Sundancer
Garmin 7610xsv
1951 Penn Yan 9' Aerodinghy/2018 AB 9vl w/ 15 hp Evinrude 2-strk
Engines
Twin 8.1 Horizons v-drives
During the winter I try and check the boat every 2 weeks. I keep the heat set to 60 to keep things dry and prevent problems with the occasional cold snaps. Checked Jan. 2, no problem. Just checked last Tuesday, the 16th, and the fan is blowing but no heat! Cabin temp was air temp., about 55. Compressor not running and no water discharge. I shut the system off for 10 minutes then turned it on. It came on and it sounded like the compressor wanted to kick on but it kicked off almost immediately. I didn’t have any tools nor the time that day. Going down to look at it in more detail this week. Any thoughts/suggestions on where to start to look for the problem. ‘05 340 in coastal NC, so the weather is not particularly extreme. Normally it can get down below freezing overnight but is usually in mid-40s to 50 during the day.
 
What is the water temp. Marine air conditioners become very inefficient below 50* and your may have run continuously and burned out the circulating pump or a relay.
 
Water temp is in mid to high 40s
 
Try switching back and fourth between AC and Heat.

The switch over valve might be stuck.

Do you have your HVAC manual? It should contain some trouble shooting info.
 
Well, got down to look at it today. System seems to be fine. Cycles between heat and cool. Dehumidifier mode works. Sounds like the compressor is coming on, but no water flow and no heat. Lifted the cover to the unit under the master berth. Voila, it is all iced up! Just like the outside unit at the beach house gets when it stops blowing heat when it is low on Freon (or whatever refrigerant they put in) and overworked. Shut the system off since it is going to be in the upper 50s for the next week or so and only in upper 30s overnight. Once it “thaws” I’ll see if water pumps, and get the coolant charged up.
 
So based on the information you have provided:
1. No heat
2. Compressor runs but shuts down after a few seconds or so.
3. No water discharge.

Fix:
1. Check circuit breaker for circulation pump if OK,
2. Sounds like the raw water pump is not working. If your unit does not detect water flow, it shuts down.
 
Also make sure the water supply line is not clogged with ice or other debris
 
Bring a multimeter and do a quick check on your capacitor and relay. Most important question for you to answer: is power getting to the compressor when the thermostat is asking for heat?
 
Your discharge line may have frozen up. Mine did in New Bern. I was going to the boat to shut down the system since the water temp was below 40 degrees, but it the discharge line had already frozen and the system shut down. Water temps got much lower than 40, even at the coast. At our condo in MHC, the entire marina froze over.
 
The temperatures in your area after your visit on 2 Jan were in the low teens with highs around freezing. Icing of the system when in the heat mode is probably a result of water temperature getting too low. Once the system iced up, your water lines may have frozen with the possibility of burning out your pump. I would check closely for water leaks if you get the system pumping water again.
 
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