Passport II marine air

[Moondog]

I bought a 1995 cruiser last fall and had a dealer of this make go over it entirely. Everything seems to work well, including this AC unit. However, I tried using the heat setting in cool spring weather, and while the control panel indicated it was in heat mode, and the thermostat was set at 85, I never got any heat out of it. Does this model include heat, or has anyone else experienced a similar problem with this brand of unit?

[redsky49]

Post model number please

[newhaul]

Here's a link to the manual hope it helps you some Passport II Manual I have no personal experience with the units

[GordMay]

Greetings and welcome aboard the CF, Moondog.

[S/V Illusion]

"Cool spring weather" doesn't indicate the water temperature. As this is a heat pump, you can only extract heat from water above a certain temperature. As you don't specify the water temp, it's not possible for anyone here to know the efficacy of a heat pump system.

[rwidman]

If it is a "reverse cycle" AC, (reverses from cooling to heating), there is a valve that is known for sticking. The common solution is to tap the valve with the handle of a screwdriver to free it.

The trick is knowing where the valve is, how big a screwdriver to use and how hard to tap it. A pair of pliers would work as well.

[Moondog]

Thanks guys for all your help. The only information I could find on the unit or in the manual is that it is called a passport II model. I could not find a specific model number although I'm sure there's one that exists. The boat is in Kentucky, so I'm sure the water temperatures are probably in the fifties right now and if it is a heat pump system perhaps water is not warm enough to create any heat. I even asked the dealer if the hot water heater had anything to do with it and they said no. I will look for the reversing valve because there was some suggestion in the manual that some of the models use a reversing system. You've given me some good ideas.

[Catnut]

I have just had the same problem. There is reversing valve that sometimes sticks, driven by a solenoid. I tried tapping the valve with a long handled screw driver, but it still stayed in cooling mode.
I removed the solenoid, tested it, and found that it had gone open circuit. Replacing the solenoid, as a temporary fix with a similar but not identical one, fixed it for us for the time being.

Tony

[kjdavie01]

One comment on the function of heat pumps. There's a misconception that the source (air or water) of heating and cooling must be warm (heating) or cold (cooling) in order for the units to function. Not true. Air-source heat pumps will heat a house to a comfortable level with an air temperature of -15 F, and will cool the house at outside temperatures of +95 F. Not as efficiently as at more moderate source temperatures, but they'll do it.
Water-source heat pumps should work just fine as long as the water is pumpable -ie. not frozen. That's 32 F in fresh water and 26 F or so in salt.

[redsky49]

Originally Posted by kjdavie01

One comment on the function of heat pumps. There's a misconception that the source (air or water) of heating and cooling must be warm (heating) or cold (cooling) in order for the units to function. Not true. Air-source heat pumps will heat a house to a comfortable level with an air temperature of -15 F, and will cool the house at outside temperatures of +95 F. Not as efficiently as at more moderate source temperatures, but they'll do it.
Water-source heat pumps should work just fine as long as the water is pumpable -ie. not frozen. That's 32 F in fresh water and 26 F or so in salt.

While correct in theory, in practical terms air source heat pumps begin to lose the battle when heating around 20F. The COP, or measurement of heating performance of a heat pump, is based on 47F outside air temperature. At that temperature a heat pump may have a COP of 3.0 or better which means it is producing three times the heat output as compared to traditional resistance heaters. As outside air temperatures drop, so does the efficiency of the unit. Correspondingly, the discharge or supply air temperature will also drop, frequently to the point that the room temperature setpoint can no longer be maintained. User complaints regarding this dropping of the discharge air temperature ( often less than 80 degrees) are the number one complaint, despite whether the unit can maintain setpoint. The air coming out of the unit feels cold. It is for this reason that domestic heat pumps have an auxiliary or emergency heat setting to energize the supplemental resistance heat.

What the OP might be experiencing is this exact condition. Being a water source unit, the seawater temperature has a direct bearing on the outlet temperature. The unit could be in the heating mode but discharging only moderately warm air.

I would also suggest that the evaporator filter, often on the back of the unit, be vacuum cleaned. I often find that these filters are never cleaned, which leads to numerous problems.

[ranger58sb]

Originally Posted by Moondog

Thanks guys for all your help. The only information I could find on the unit or in the manual is that it is called a passport II model. I could not find a specific model number although I'm sure there's one that exists. The boat is in Kentucky, so I'm sure the water temperatures are probably in the fifties right now and if it is a heat pump system perhaps water is not warm enough to create any heat. I even asked the dealer if the hot water heater had anything to do with it and they said no. I will look for the reversing valve because there was some suggestion in the manual that some of the models use a reversing system. You've given me some good ideas.

Passport II is the nomenclature for the control panel system. A more modern one is the Elite control panel, etc. and that ads some programmable features.

Not sure what the actual reverse cycle unit nomenclature is... and I'm here, and docs are there. (And if I remember right, the "manual" isn't all that informative, except for installation instructions.)

Anyway, that's the system we have.... and yes, it's supposed to put out heat if the reversing valve is working. Not to be confused with an additional resistive coil arrangement that could have been fitted on some systems, too. Give no heat output, you likely don't have that resistive addition anyway.

-Chris

[a64pilot]

A way to determine if the reversing valve is functioning is to change from cooling to heating mode when the unit is operating, if the valve functions, there should be a loud "whoosh" noise when it functions.
I want to think that around 50 deg water temp is about where a marine heat pump loses it's capability to produce much heat, to some extend the amount of water flow through the system also contributes, so if the strainer is partially blocked, you lose efficiency there too.

[rwidman]

Originally Posted by ranger42c

Passport II is the nomenclature for the control panel system. ...............

True. The information for the air conditioner would be on the air conditioner itself.

[redsky49]

A unit capable of heating (and not all are by the way) would either have an electric resistance coil or would have a "reversing" valve in lieu of a typical thermostatic expansion valve. The ability to both heat and cool utilizing a compression cycle makes it a 'heat pump'.

If you can determine the amperage being used, either by a panel mounted ammeter or a multimeter, the first thing I would check is if the amperage increases when you go from the 'FAN' position to the 'HEAT' position. There should be a big leap of from 6 to 12 amps over fan only,typically.

Having a control panel that shows a heat position is encouraging but not definitive. What exactly did the refrigeration rep do while examining your unit? Or were you referring in post #1 to the rep for the boat manufacturer?

[redsky49]

Originally Posted by a64pilot

A way to determine if the reversing valve is functioning is to change from cooling to heating mode when the unit is operating, if the valve functions, there should be a loud "whoosh" noise when it functions.
I want to think that around 50 deg water temp is about where a marine heat pump loses it's capability to produce much heat, to some extend the amount of water flow through the system also contributes, so if the strainer is partially blocked, you lose efficiency there too.

Generally, if the strainer is blocked the unit will go off due to high head pressure, or perhaps trip the breaker.

I will admit that I am not a marine HVAC technician, though I am a retired Mechanical Engineer, so take my comments with some caution.

I would also take some accurate temperature measurements, incoming/return air and outgoing/supply air and note the delta.