Air Conditioner

PlaneGuy

PlaneGuy

Active Member
SILVER Sponsor
Jun 21, 2022
115
Huron Ohio
Boat Info
2000 340 Sundancer
Engines
Mercruiser 7.4L
Well I fired up the AC and it works fine. As for a little heat the unit will come on, the air begins to get warm and after about 30 seconds the heat stops. The fan continues to run however. I have water flow so I have no ideas what is going on. Help!!!!
 
Tap on the reversing valve with a metal hammer. It could possibly be partially stuck. You could also switch back and forth between AC and heat and may free it up.
 
My ac will cycle on and off in pretty short cycles….. and my units are new
 
If water is 50*,its going to take several minutes for it to produce any heat. Turn it on and let it run 5-10 min with the thermostat turned up. If after that, no heat, then try tapping the reverse valve as mentioned.
 
Occasionally switching the unit function between AC and heat a few times a season is a good practice anyway. That "exercises the reversing valve and helps prevent it from getting stuck.
 
You might try removing the duct work from the unit and see if that makes a difference. On my last boat, for some reason, the duct work would not allow enough airflow for heat. AC was fine, just had this same problem with heat. As I live in So FL, it was a very minor issue for us.
 
dtfeld said:
If water is 50*,its going to take several minutes for it to produce any heat. Turn it on and let it run 5-10 min with the thermostat turned up. If after that, no heat, then try tapping the reverse valve as mentioned.
Click to expand...
Yup, what I was inferring with my comment.
 
b_arrington said:
Occasionally switching the unit function between AC and heat a few times a season is a good practice anyway. That "exercises the reversing valve and helps prevent it from getting stuck.
Click to expand...

Good advice. The 420DA I just sold had a newer 16,000btu Dometic Turbo unit. The boat came from FL where heat was never needed and it was never put in the heat mode. The reversing valve in a marine unit defaults to the cooling mode so having never been used to heat, the valve was stuck. You could tap on it and sometimes it would shift, but for the most part no go in heat mode. Removing the thing to get to it was going to be a chore. We just used a small ceramic heater that made no noise and got by just fine. Luckily, the boat went back to South FL and heat was not needed anyway.

Bennett
 
Well we have another issue. After replacing the blower motor and condenser in the spring the air conditioning worked great. Even on a 90 degree day the cabin would cool to 73 degrees with no problem. The last couple of nights on the boat a small amount of heat would have been great....and this is the issue. When I turn the heat ON the unit will come on and the air will get warm. After about 3 minutes the circuit breaker for the A/C will pop. Now back in the spring when I tried to use the heat it would shut down, cool down and come back on. It never actually popped a circuit breaker. This unit has a Cruisair Auxiliary Heat Module installed in the line. From what I can determine it was installed by the original owner. Keeping in mind the heat and air worked fine last season. I am not familar with the heat modules can anyone tell me how they work? Thanks.
 
1. Does it pop the breaker on cool? If so, it has nothing to do with the heat setting - pure coincidence.
2. Verify that right before it pops you hear the compressor come on
3. Assuming it does, does the water start pumping?
4. It's possible the reversing valve is stuck, but I haven't heard of that causing it to pop the breaker. You can try tapping on it with a screwdriver to loosen it up or even start the heat cycle, then go to cool, then back to heat, etc.
 
douglee25 said:
1. Does it pop the breaker on cool? If so, it has nothing to do with the heat setting - pure coincidence.
2. Verify that right before it pops you hear the compressor come on
3. Assuming it does, does the water start pumping?
4. It's possible the reversing valve is stuck, but I haven't heard of that causing it to pop the breaker. You can try tapping on it with a screwdriver to loosen it up or even start the heat cycle, then go to cool, then back to heat, etc.
Click to expand...
Since the boat has an auxiliary heat module installed, I'm not sure that a reversing value comes into play. The module is an electrical resistance heating element intended for use when sea water is too cold to produce reverse-cycle heat.

Good point about checking that the breaker is stable when the AC is on.

Perhaps the heating element has an issue and is drawing too much power?
 
b_arrington said:
Since the boat has an auxiliary heat module installed, I'm not sure that a reversing value comes into play. The module is an electrical resistance heating element intended for use when sea water is too cold to produce reverse-cycle heat.

Good point about checking that the breaker is stable when the AC is on.

Perhaps the heating element has an issue and is drawing too much power?
Click to expand...

I was not aware. You're suggestion is likely onto something with the heating element.
 
douglee25 said:
1. Does it pop the breaker on cool? If so, it has nothing to do with the heat setting - pure coincidence.
2. Verify that right before it pops you hear the compressor come on
3. Assuming it does, does the water start pumping?
4. It's possible the reversing valve is stuck, but I haven't heard of that causing it to pop the breaker. You can try tapping on it with a screwdriver to loosen it up or even start the heat cycle, then go to cool, then back to heat, etc.
Click to expand...
1. No the breaker only pops after the heat is On for a few minutes
2. Yes the compressor is already running
3. Water is pumping and the strainer is clean
4. The air is warm
 
douglee25 said:
I was not aware. You're suggestion is likely onto something with the heating element.
Click to expand...
I should have mentioned that I had a mechanic remove the power from the heating module and it still pops the breaker.
 
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