Air Conditioning Shut-down

[JohnH]

When I turn on the AC on my R-27, it runs normally for almost exactly 45 minutes, then shuts down -- no cooling, not even the fan. The display reads "HPF", which, according to the manual, means some kind of blockage in the cooling water feed, I think. If I turn off the AC for a few minutes (actually, as little as ~ 1 minute) and then turn it ON, it will run properly for another 45 minutes, followed by the same shut-down and "HPF" display. Doing another OFF and ON cycle then generally brings operation for as long as I care to run it (it has run for a few hours after this).

It doesn't seem like a water flow issue to me, because I have done nothing to clear the line between OFF and ON cycling as above, and water flow is fine when it is running. The air flow outlets and return vent are not obstructed, at least not that I can see.

On the days when I observed the above behaviopr, it was quite hot, and the interior temperature of the boat at the beginning as measured by the AC control) was 95 degress or even 100+ degrees. The water temperature (as reported by the weather service) was ~ 80 degrees. These are probably difficult conditions for the AC to handle, but I think they are within its spec.

I have not looked extensively for icing, but is it plausible that ice could have formed and melted in the times above (melting in ~ 1 minute)? The manual mentions that the compressor could get hot, but it indicates that it could take hours (not minutes) to recover from this situation.

I welcome suggestions for cause and cure.

Thank you,
John H

 

[abcandjrc]

My first thought is that you have a programmable thermostat and are just remarkably precise in the times you use the boat. 🙁

Based on the continuous run after a couple 45 minute shutdowns though, I would suspect a control problem more than a mechanical one. Very strange behavior since you would expect to have a long run followed by a series of shutdowns if the problem were with the compressor/condenser components.

Is it possible that as it finally reaches the sustained run the ambient temperature has dropped and the load has lessened a bit? Toward evening, for instance. I suppose something really weird could be happening like an air bubble that eventually clears, but that is not very likely and sure is reaching for a solution.

I bet you will eventually have to contact the manufacturer of the unit on this one. Perhaps they have experienced the problem and may have a ready solution. Most likely, some replacement electronics.

 

[Ainokea]

The pump also has a thermal switch on it. If the pump motor overheats it will shut off and the panel will display HPF. The pump uses intake water to cool the pump motor. The cooling line is of a small diameter and can get restricted.

I had that issue as well as the ducting vent at the seat not being sealed correctly allowing for some cold discharge air to be pulled right back in to compressor area giving false sensor readings. The area Dometic dealer came out to boat and reseated ducting flange and installed a secondary temp sensor.

I also suggest contacting either the Ranger Factory or AC dealer. May be something easy

 

[golftrek]

We recently had something similar. The air conditioner would run about an hour, then stop and show the HpF code and then shut down. If we touched the pump it was hot. Next time we tried the ac It would runabout an hour, then shut down. We cleaned the sea strainer, that did not help. We called in a technician and he disconnected the outflow hose to the pump and then blasted high pressure water into the hose. Out came a lot of mud. The ac is running fine now. This is evidently a common problem in North Carolina with muddy bottoms. We now know how to fix the problem.

Jim and Jo Ann. Banjo 2008 R 25

 

[assignment]

We've had the HPF fault several times too. My manual is on the boat but I do recall it describing some causes...like a blocked seawater strainer. You probably have a MarineAire unit like ours (we have two, one in the main cabin and one in the salon). With ambient outside air temps approaching 100 degrees and seawater temps about 85 degrees, the unit will be working hard to cool the boat. After 4 faults in a row, our salon unit "locked out" and I had to re-code its remote panel (with a local technicians help). We had a clear strainer, our main pump was working and air filters were clean. I did notice a droop in the output lines from the compressor so I zip-tied them and we have not had a problem since. Might want to look for any restrictions in those output drain lines as I've been told the units are quite sensitive. The compressor will be very hot (normal condition) so watch your hands. It also will cycle off to in a melt mode then usually turns back on after a minute or two. The technician did mention that muddy or dirty water can leave sediment in hoses contributing to restricted flow or blockage.

We have some techniques which have helped us during the hot Virginia summers...usually just needing our aft unit (in the salon) to cool the boat. First, after checking seacocks open and proper electrical loads set (30 amp shore power, etc.), turn on the unit and set the thermostat within 3 - 5 degrees of what's indicated in the remote unit. We have all shades closed and overhead hatches blacked out. We then clip a fan at the forward cabin door to help cycle the air aft (where our thermostat is). As temps start to cool, start bumping your temp down to desired setting. This seems to be quite effective for reliable use. We can expedite cooling by turning on forward cabin air once our 30 amp electrical load has stabilized.

Hope this helps some!
//Bud

 

[doke01]

HPF means overheating and this is, in my experience, due to no or restricted cooling water flow. Since yours is working for a period of time I would suspect restricted water flow that is just enough to cause a slow overheating over time that eventually shuts off the A/C. Cooling also depends on water temp, so in cooler water you may see no issues. Check for a clean filter, barnacle growth/blockage of your thru hull pickup, and water flow from the pump out the side of the boat. I clean the filter and thru hull and then disconnect the pump outlet and make sure when the pump engages I have a strong flow. Then I will take the nozzle of my water hose and put it against the hose I removed from the pump outlet and blast water through the hose. In one case I had to be a length of electical wire as far as it would go and then blast with the hose. Finally, there are some tabs in the cooling water exit thru-hull (used for thru-hull installation) that will sometimes catch material and restrict/block cooling water flow. I have also had sea grass lodged in the hose between the inlet thru hull and the filter. Any of these things will cause restricted water flow, poor cooling, and ultimately overheat and shut-down. Once you clean any restrictions you will also notice that the A/C will blow much cooler.

 

[JohnH]

My thanks to all for these helpful responses. I will check the water lines more thoroughly next time I visit the boat. I note, however, that I already have checked the seacock, the strainer, and the hose up to the pump, and there seems to be good, unrestricted water flow. I note also that, when the AC is working, there is a good and steady flow of output water -- i.e., it comes out the hole at the full diameter of the outlet port, and the stream projects about a foot from the boat before it hits the harbor water. It also mystifies me as to how, after one or two shut-downs, the AC might then run properly for hours. This shut-down followed by proper operation is immediately sequential, with no reason to suspect any significant differences in air or water temperature and no effort to purge or clear water lines.

Is is true that the troublesome behavior happened when water temperatures were at least 80 degrees (and maybe a couple of degrees higher) and the air temperature inside the boat when I first turned on the AC was near or even above 100 degrees. Am I just expecting too much, but aren't these conditions within operating specs? Of course, these are the times when you really, really want the AC to work.

Thanks again,
John H

 

[Levitation]

You need to blow water through the compressor... Take the hose off the intake sea strainer and connect it to dock water, then turn the water on and let it flush out the AC hoses...

On my boat I have put a Tee in the sea water line to the AC with a valve to be able to switch the incoming water to a standard hose coupler and connect to the dock hose... So far (knocking on wood as i type) I have had no AC problems since beginning this routine...