Air Conditioner Reversing Valve Issue

Rich Stidger · May 31, 2018

Maybe I mis-stated. It is the evaporator that becomes solid with frost. Then the gas is not warmed in the evaporator and returns t the compressor. The system doesn't like this condition and everything shuts down. I am surprised you haven't seen this condition.

JamesG161 · May 31, 2018

Rich Stidger said:
the gas is not warmed

One assumption...
If your Receiver has adequate level of refrigerant, then your change in pressures from Discharge to Suction should be the normal. You can laser temperature shoot the Receiver [the big black tank in pictures] and detect its refrigeration level, when your compressor starts to run.[Top vs Bottom]
______
You can also do a change in temperature measurement on the inlet to the "air mover coil" [the thing with the fins] and exit. No temperature difference, no Heat movement [negative Heat is cooling].
The reversing valve determines that coils name in a Heat Pump AC.
______
There are 2 heat exchangers on a marine Heat Pump.
1) The Fin Cooler for Air
2) The refrigerant exchanger using sea water.

If either one of these Exchangers is "fouled" your marine Heat Pump will NOT work correctly.
____
1) The Air exchanger can be visually seen and using a compressed canned air, can normally cleaned. If there is "gummy stuff" on the fins, you can get a "Coil cleaner" or I like Purple Power and a water rinse.
______
2) You can't see the fouling inside the sea water exchanger., but you can do a Temp In/Out check too.
The fouling is NOT on the refrigerant side, but on the sea water side.

This sea water side fouling is symptomatic of all of the issues I see in this post. Good sea water flow, does not mean good heat exchange.
_____
Oh great Jim, how do I clean that exchanger that is welded shut?
Ans: It depends on where you are located, fresh or salt water, algae, barnacle, or Carbon Di-Crapite fouling.
Jim...

PS: I can discuss methods on how I keep mine clean in a PM or phone call.

JamesG161 · May 31, 2018

The Sea water cooler, is shown as the White Square-ish thing in Terry's picture on his post #15
The water flow on the outside or the painted area.
the refrigerant flow in the center of that white loop. You can see the copper tubes going in and out the other side [that is the refrigerant line].

You can check that inlet and outlet temperatures too. No change or little change in refrigerant temps, the sea water cooler is fouled.
Jim

SG · May 31, 2018

He wants it be in Heat mode.? It’s cold and damp?

Doug4bass · May 31, 2018

Hi Monterey.
I have the same unit in my 385. A good tech at Pompanette in Tampa in Dave Smith. He helped me out immensely with my unit when the circuit board fried. He is from the U.P. So he payed
us a service call/ visit when he was up here, and spent a few hours in the hell hole. He may have retired, not sure, but he wrote the manual on your unit. Might want to call back and see if he's
still there.

Terry Cox · May 31, 2018

Monterey385 said:
I have a common problem … my air conditioner cools okay but does not heat.

Very interesting post and follow-on discussion. Never use either of our original 1991 R-22 heat pump systems to cool the boat. Very moderate climate around these precincts. During our winter cruises or visits to the boat I will use one or the other for heat while connected to shore power. Amazing how much heat these systems extract from 40-45 degree water.

After all these years I noticed the aft cabin system (9K BTU) delivered no heat, so I paid a marine refrigeration guy to check both systems last season. Main cabin system (16K BTU) checked out fine. Aft cabin was low on R-22 so he said it took a couple/three pounds of refrigerant. He also checked out both heat and cool sides.

Also, that original Little Giant that supplies sea water to both pumps runs for hours, sometimes all night/day without a complaint. Maybe someday one or both will stop, but until then...

JamesG161 · May 31, 2018

Terry Cox said:
couple/three pounds of refrigerant

That sounds WAAYYYYY to much R-22. If the system leaked that much you should have seen the oil spray near the leak.

I have the same configuration as you, Terry. LOL, not too often on HEAT cycle, except deep winter.
Jim...

Doug4bass · May 31, 2018

Monterey...
No need to pm...
The original unit in our boat lost it's refrigerant somehow, and instead of Pompanette troubleshooting, they replaced the whole unit. Only problem was a poor install by a poor tech at the dealer. The A/C feeds came loose and nearly burnt up the boat. Dave installed the new board. A great guy. And entertaining.

Terry Cox · Jun 1, 2018

JamesG161 said:
That sounds WAAYYYYY to much R-22. If the system leaked that much you should have seen the oil spray near the leak.

Hi James. A novice here, so likely conflated/inflated the amount based on memory. I do remember he said no visible or detectable signs of leaks, just normal after so many years. Whatever amount he put in that did the trick. Used it this past year during our winter cruise while connected to shore power at a nearby reciprocal dock.

All other times, while on the hook, we rely on our Wallas 40D forced air furnace for boat heat/comfort. It, like our heat pumps, does a yeoman's job of keeping the admiral happy during these off season excursions.

JamesG161 · Jun 2, 2018

Terry Cox said:
the amount

A couple or three OUNCES sounds possible.

Your system is sealed. If not, no Heat or Cool cycle.
Why do you ever need to add refrigerant then?

Even though Freon® [R-22] is "inert" or not reactive, it needs lube oil for the sealed compressor. Slow decomposition, by use, of the oil and Freon® turns into solids, thus the need for a in-line filter. I am not sure about the new replacement R-410.

Unless the Technician changed the filter too, then it should be few ounces for the small sized units, on sports boats.[true too for most Landlubber AC units]

Note: When installing a new system, they purge all the boat's copper lines with Nitrogen and evacuate them [200+ mm Hg vacuum] . The Receiver Tank is pre-filled with Refrigerant/Oil mixture. The size of that Receiver Tank is for filling the entire system of copper [memory says ≈20' of lines in/out] and 1/4 ounce more per foot, of standard sized lines, is added, if longer lines. When prepared, the Tech simply opens the Receiver Tank and "fills" your sealed, evacuated system.

Jim...

PS: I am sure this is more info than needed, but done for the OP.

Terry Cox · Jun 2, 2018

JamesG161 said:
PS: I am sure this is more info than needed, but done for the OP.

Thanks Jim. Good to know.