Winterizing HVAC

[Lshulan]

On a 2002 MS 390, there are two air conditioners, one is located under the berth in the master stateroom. Where is the other one? And I understand that while two air conditioners, there’s only one pump, is that correct? The PO gave me good instructions for winterizing the HVAC by hand pumping antifreeze thru the DISCHARGE holes to drain back thru each system and then it will drain into the strainer. Thoughts on this?

 

[rslifkin]

I've always done mine by feeding antifreeze into the strainer with the system running, then turn it off once it's spewed a bit of antifreeze out the side. 2 of my 3 systems share a pump, so only 1 of them has to be running for both to get antifreeze flushed through.

 

[DavidM]

Pouring antifreeze into the strainer while running the A/C may not work if the pump can't get a prime. These are usually non self priming pumps. I take the hose off of the strainer outlet, raise it up a foot or so and then pour antifreeze in while the A/C is running.

Back to the PO, he may have a split system with the A/C compressor in one place with freon tubing feeding two separate air handlers. Not a common situation though. More likely one raw water pump feeding two separate compressor/condenser/evaporator/fan systems.

David

 

[Bacchus]

I have messed with containers up on aft deck w hoses to feed the strainer to prime the AC pump. After reading a suggestion here on TF I added a T in the thru hull to strainer inlet and added a garden hose fitting and cap for normal operation.
When winterizing I do my raw water system first by using a rubber stopper with a 1/2" pipe / hose barb inserted into the stopper.. I use the stopper in place of the strainer cap and the hose will suck pink out of jugs. Once my raw water system is full of pink I attach a short hose from my aft deck raw water outlet to the AC strainer T. The raw water pump pressure now forces antifreeze through the AC system w/o worrying about priming.

I have seen some that plumb the raw water to AC strainer permanently with a ball valve in the connection. This makes priming or winterizing the AC system as simple as opening / closing a ball valve.

If one pump supplies 2 ACs a pair of (Harbor Freight) hose pinch off pliers is useful to limit flow to each AC separately.

 

[Duetto]

i use a spare jabsco 12v water pump. i disconnect hose on the output side of strainer and connect the jabsco to that. input side of jabsco has hose into pink jug. turn on and suck the jug dry and you're done.

 

[Lshulan]

Thanks for the good info. I had asked about where is my other air conditioner. I’m assuming since I have two sets of controls and two separate breakers that there are two air conditioners. Also, I get discharge from the front one on port side by bow and the other on starboard side, between midship and aft, not really sure exactly where and this poses a separate question, there are three white plastic thru hulls above water line more or less mid ships, not sure which is air conditioner. Does anyone have this setup and can tell me where second ac is and which thru hull is for ac?

 

[Bacchus]

Larry
I'm not really familiar with the 390 systems layout.
Did you not get a MS manual with the 390?
Is there a return air grill for the mid / aft AC unit? usually the return air grill is very close to where the compressor & evaporator coil is located.
Can you see the inside of the thru hulls from the eng rm? If so you may be able to trace the hoses back to determine where it originates.

 

[ssurabus]

On my 40T, I added a bleeder valve just downstream of the pump to make it easy to prime the AC system. To winterize, I open the strainer and use a Sea Flush funnel attached to bucket that I rigged up with a valve and hose at the bottom. I place the bucket on a towel on the salon floor, fill it anti-freeze and open the valve to allow flow into the Sea Flush/strainer. Once I crack the bleeder valve, it flows through the pump (it's not like an impeller that doesn't allow flow) and when I see some antifreeze drip out the bleeder I know the pump is primed. Then I run the AC and it the antifreeze gets pulled right through the system. Before I had a good way to prime it, it was an exercise in frustration. That valve is also handy anytime the boat is hauled and I need to reprime. I'm not at the boat or I'd include a pic.

 

[DavidM]

Follow the water discharge back to the A/C unit (or forward from the raw water pump) to find the missing A/C unit.

David

 

[ranger58sb]

On a 2002 MS 390, there are two air conditioners, one is located under the berth in the master stateroom. Where is the other one? And I understand that while two air conditioners, there’s only one pump, is that correct? The PO gave me good instructions for winterizing the HVAC by hand pumping antifreeze thru the DISCHARGE holes to drain back thru each system and then it will drain into the strainer. Thoughts on this?

Don't know your boat, but two ACs and one pump is certainly feasible.

IF you are doing the work on land, then yes, back-feeding via the discharge thru-hulls... through the strainer... and eventually out of the boat through what is normally the AC intake... apparently works. (All that from reading.)

We more often over-winter in the water, so our process starts at the other end. Close the thru hull. Clean the strainer. Inject AF through from the strainer end.* Discharge comes out through the normal discharge thru-hulls.

* We've inserted Groco "Safety Seacocks" just after our strainers, and use their "service adapter" to connect a hose for AF injection. Trac sells a replacement strainer lid for Groco strainers, another easy way to connect a hose for AF injection.

We just use a battery-powered transfer pump to push AF through the systems. Avoids priming issues. Or, once the system is full using the transfer pump, turning on the AC pump will pull more AF through faster.

-Chris

 

[fletch]

I have two pumps, one small one large, with corresponding Graco strainers. I bought two spare strainer caps, drilled holes and connected tubing. I have a standard submersible pump, use a 5 gallon bucket. My discharge lines all have valves, shut them all, start pump, open then shut when I see pink in the nylobraid tubing.

 

[skipper724]

AC unit on 390

The main unit is under the staircase going up to the bridge. It is accessible through the air vent in the main salon near the slider.

The easiest way to winterize IMO is to remove the hoses from the pump, attach a spare pump to the hose and pump a gollon through as one of the members said. Reattach the hoses and you're done!

 

[Pete Meisinger]

Probably only one pump.

pete

 

[Comodave]

We had 2 Trac adapters for the Groco strainers that we pumped antifreeze through. Worked like a charm. We used a SeaFlush to winterize the main engines.

 

[fgarriso]

Check the output of your pump and see if it splits off in two different directions. FYI I would install one pump per AC unit.

 

[Circumnavigator]

I solved the loss of prime problem more simply than above. Take the hose off the seacock. Stick it in a gallon of antifreeze. Start the pump (it can run dry for a few second). Use your left hand to make a seal while you invert the gallon above the pump with your right. Once the pump starts sucking, you can put the gallon down upright and stop the pump when the gallon is empty.


In doing this, I have a small advantage -- the PO installed a switch for the pump immediately above it.


You'll lose a little antifreeze, but it's harmless and only $4 a gallon at Home Depot or Walmart.


Jim

 

[Chuck34]

You need to open your eyes and do a quick search for that second AC unit. It can’t possibly be hard to find. Turn on one at a time, determine which vents are supplying air and find the air return. Do the same for the second unit. You must find both air returns as most likely they have filters installed and there is a real good chance they need to be cleaned or replaced. Most likely, they have those steel mesh filters that can simply be hosed off for cleaning.

As far as winterizing goes, I’ve been pouring anti freeze into the strainer with the unit running for years. Easy, peasy, Never had a problem. Chances are real good you only have one pump for both units and only one compressor needs to be running to have AF flow through both units.

 

[slowgoesit]

Chuck 34 hit a VERY important point. If you don't know where the HVAC unit is, the filter has probably never been changed! Also, one pump for each AC, or two pumps, with two associated control boxes for two AC's are both common. The main reason for one pump for two AC units is to save money. For our boat, when replacing the original HVAC units (which I am currently in the middle of), I elected to go with two raw water pumps, and two separate control boxes, one for each HVAC unit. That way, if one raw water pump, or one control unit fails, I still have ONE functioning HVAC, until I can repair the other one. YMMV

 

[pmck]

On My 400 with two a/c one pump I blow air from the discharge port (two) and all the water comes out at the through hull on the intake. I then blow it again at the a/c unit. This has worked for me. I can't get at the strainer, so this is the method I use. In the spring I do the opposite to get the a/c motor primed.

 

[ssurabus]

Pmck,

If you don't mind, I have a couple of questions about your method (I've got same boat, same AC setup).

1) You are blowing with a shop-vac starting at the discharge ports outside the boat, back through the system, with the seacock opened at the other end....correct?
2) Could you clarify what you mean by 'blow it again at the a/c unit'
3) I'm curious why you can't get to the strainer

Blowing the AC out with air seems to be fine, but I've been too chicken to this point not to run some coolant through.

 

[Chuck34]

Thanks for the good info. I had asked about where is my other air conditioner. I’m assuming since I have two sets of controls and two separate breakers that there are two air conditioners. Also, I get discharge from the front one on port side by bow and the other on starboard side, between midship and aft, not really sure exactly where and this poses a separate question, there are three white plastic thru hulls above water line more or less mid ships, not sure which is air conditioner. Does anyone have this setup and can tell me where second ac is and which thru hull is for ac?

Which one is the AC discharge? Turn on one or both of your AC units where the compressor is running and see which thru hull is the discharge. As far as the other two, could be a sink drain, or more likely, a bilge pump discharge or sump pump discharge.

 

[pmck]

1)Yes a shop vac. 2)on both my A/C units there is a mark indicating flow at the connection of a hose. I blow out the hose. 3) the strainer is right up against the bulk head and I cant fit anything in there. I also checked the owners manual of the a/c units and the they indicate that you can use this procedure. I think my units are MarineAir.

 

[Lshulan]

So here’s the final word on this, all done. The second AC unit was where suggested, behind the intake vent stbd side at rear of main cabin. Tried to follow the discharge hose (which was clearly marked!) but didn’t get to hull as inner wall in way. But, and this is a big but, it became apparent that it would be extremely easy to simply remove the discharge hose and insert my pump into fitting and accomplish the pump through system until discharge turned pink. It took just about 1/2 gallon of antifreeze (which was what PO had said in his chat). Then went to forward discharge fitting at bow on port side and pumped another 1/2 gallon through until discharge turned pink. Actually, much simpler than I thought. Next year I’ll be sure to see which outlet on stbd side is the discharge and then will even be easier. Thanks to all for help and bearing with a new owner going through a complicated winterization process.

 

[ssurabus]

Thanks



QUOTE=pmck;1134378]1)Yes a shop vac. 2)on both my A/C units there is a mark indicating flow at the connection of a hose. I blow out the hose. 3) the strainer is right up against the bulk head and I cant fit anything in there. I also checked the owners manual of the a/c units and the they indicate that you can use this procedure. I think my units are MarineAir.[/QUOTE]

 

[Comodave]

1)Yes a shop vac. 2)on both my A/C units there is a mark indicating flow at the connection of a hose. I blow out the hose. 3) the strainer is right up against the bulk head and I cant fit anything in there. I also checked the owners manual of the a/c units and the they indicate that you can use this procedure. I think my units are MarineAir.

On our last boat the strainer for the genset was directly under a sewage hose. I built a spacer and moved the strainer off the bulkhead so I could get to the top for winterizing. It was tough getting the spacer installed but it was worth it every year when I went to winterize the boat. Also while I never had any issues with the strainer clogging it would have been easier to clean the strainer if it did clog.

 

[ssurabus]

On my 40t there is enough clearance from the bulkhead to open the strainer and insert the sea flush funnel. From there it is easy to blow the whole system out with a shop vac. I am sure that is sufficient but I follow up with some antifreeze for good measure. If my strainer was directly against the bulkhead I would try to move it too.