Air Conditioner Problem

[psneeld]

Scenario - Approximately 20 year old split unit, reverse cycle 16500 btu MarineAirrrrr unit in main salon. Water pump died a month back and was replaced in kind. Water pump and new cycling issue may/may not be related. Unit now runs fine for 5-10 minutes, 65 degree air blowing, 50 degree coils, with 90 degrees in cabin.... then compressor cycles off but trips nothing with fan still blowing. It has come back online after a period of time but most of the time I've just turned it off after the compressor has shut down.

The refrigerant low side is between 70-80 psi when the compressor is running.

The control unit is the old style 3 knob off/on, fan speed, thermostat.

Any ideas? Didn't see anything in the troubleshooting manual.

Thanks!

 

[Keith]

Is the cooling water flow good outside the boat and is the water warm? You might have gotten some gunk in the heat exchanger when you changed the old pump out. Might just try hooking up a water hose to the circuit and blowing it out.

 

[RickB]

Is it a true "split" with the evaporator in the air handler?

What is the refrigerant?

What is the discharge pressure?

 

[psneeld]

Is it a true "split" with the evaporator in the air handler?

What is the refrigerant?

What is the discharge pressure?

Kieth...water flow is good

RickB...yes true split
R22 still (at least PO didn't re-label)
Don't have a full guage system...

 

[RickB]

Kieth...water flow is good

RickB...yes true split
R22 still (at least PO didn't re-label)
Don't have a full guage system...

The suction pressure sounds within limits, it would be interesting to know the discharge pressure just to confirm. Is there a large temperature drop across the condenser with regard to gas in and liquid out?

I would check the compressor current draw and see if there is an internal problem with the motor. Check the air handler as well to see if the fan motor might be drawing too much current. It doesn't sound like a refrigeration issue per se.

 

[psneeld]

The suction pressure sounds within limits, it would be interesting to know the discharge pressure just to confirm. Is there a large temperature drop across the condenser with regard to gas in and liquid out?

I would check the compressor current draw and see if there is an internal problem with the motor. Check the air handler as well to see if the fan motor might be drawing too much current. It doesn't sound like a refrigeration issue per se.

I'm thinking controls or processer board somehow too...nothing is tripping a breaker...the compressor just stops compressing....everything else normal.

 

[RickB]

Try leaving the power on after it quits next time and see if it restarts on its own then quits again. I don't know if the logic board will permit that kind of start though, do you have to go to the thermostat to start the unit each time after a power loss like when changing from shore to onboard power? If not and if it restarts after taking a break, I would consider the compressor overload safety switch as likely suspect.

 

[psneeld]

Try leaving the power on after it quits next time and see if it restarts on its own then quits again. I don't know if the logic board will permit that kind of start though, do you have to go to the thermostat to start the unit each time after a power loss like when changing from shore to onboard power? If not and if it restarts after taking a break, I would consider the compressor overload safety switch as likely suspect.

thanks...I'll be taking a look there as there is no logic board that I know of...it's the old neanderthal system...on/off, fan, thermostat. Even the pump runs all the time the unit is "on" but not compressing.

may look into control updates just to break into the 21st century...might be all that I need..

 

[RickB]

What is the model number and vintage?

 

[psneeld]

please don't scold me...she has seen her service life...

model says C16H marine air...looks original as the ser number starts with year the boat was delivered "87"....

that's off the unit plate...don't have any other documentation.

 

[RickB]

... please don't scold me...she has seen her service life...

I like old stuff ... I have a lot in common with most of it.

 

[psneeld]

I like old stuff ... I have a lot in common with most of it.

true...and it looks like she has life in her...just a weird pattern of operation for the limited number of reasons why it would kick off.

 

[RickB]

I tried to find a schematic but your unit must have been built before the printing press was invented.

Look on the compressor casing for a "Klixon" type switch, probably held on by a wire clip. If there isn't anything then it might be inside the can.

If you are ambitious, when it quits next time, ring out the compressor power leads and see if you get an open. Ring it out before it quits next time so you will know what to expect.

If that doesn't get you anywhere, hot wire the compressor and fan and see what it does. At least you can eliminate those items.

 

[psneeld]

I tried to find a schematic but your unit must have been built before the printing press was invented.

Look on the compressor casing for a "Klixon" type switch, probably held on by a wire clip. If there isn't anything then it might be inside the can.

If you are ambitious, when it quits next time, ring out the compressor power leads and see if you get an open. Ring it out before it quits next time so you will know what to expect.

If that doesn't get you anywhere, hot wire the compressor and fan and see what it does. At least you can eliminate those items.

Thanks...right down the road I was headed...just posted to see if some other poor slob did all my homework for me first... and found something easy and simple...you know the stuff that never happens for me...on a BOAT nevertheless!

 

[Forkliftt]

thanks...I'll be taking a look there as there is no logic board that I know of...it's the old neanderthal system...on/off, fan, thermostat. Even the pump runs all the time the unit is "on" but not compressing.

may look into control updates just to break into the 21st century...might be all that I need..

PS, there is an adjustment for the thermostat on the old dial units. If it has reverse cycle heat like mine you should feel a "click" from cool to off and then another "click" as it goes from off into heat. Off should roughly be in the center of the dial. If this is not the case, with the breaker off of course, remove the knob (two flat head screws) and you will see a small hole on the face as I recall. Use a flat long small screwdriver to reach in there and turn the screw slightly till you hear it click. It could be in or out- so consider this a disclaimer. Another possibility is the high pressure switch is failing. Mine also did this. Check your electrical schematic. It is mounted beside the compressor in the high pressure line.

 

[bluebyu]

When the compressor "turns off", is it still running, but unloaded?

I have a vintage 1984 Marine Aire, the thermostat is bad, it always keeps the compressor unloaded.

From memory, there are 2 solenoids, one for reverse cycle, one to load and unload compressor.

Hope this helps.

 

[psneeld]

PS, there is an adjustment for the thermostat on the old dial units. If it has reverse cycle heat like mine you should feel a "click" from cool to off and then another "click" as it goes from off into heat. Off should roughly be in the center of the dial. If this is not the case, with the breaker off of course, remove the knob (two flat head screws) and you will see a small hole on the face as I recall. Use a flat long small screwdriver to reach in there and turn the screw slightly till you hear it click. It could be in or out- so consider this a disclaimer. Another possibility is the high pressure switch is failing. Mine also did this. Check your electrical schematic. It is mounted beside the compressor in the high pressure line.

thanks..a real possibility...just not hot enough to get too anti- Buffet and tear into her just yet!

 

[psneeld]

When the compressor "turns off", is it still running, but unloaded?

I have a vintage 1984 Marine Aire, the thermostat is bad, it always keeps the compressor unloaded.

From memory, there are 2 solenoids, one for reverse cycle, one to load and unload compressor.

Hope this helps.

no... the compessor stops running...

 

[Forkliftt]

thanks..a real possibility...just not hot enough to get too anti- Buffet and tear into her just yet!

No need to tear very far. Believe it or not, I pulled my thermostat loose this weekend and grabbed a couple of pictures with my iPhone so now I can share. A marine AC tech shared this with me once when mine acted up. As I recall, all you need is to remove the knob as one picture shows. Then notice the springs and brass colored adjustment screw in the other pic. As you adjust it, it changes the spring tension on the small round part the capillary tubing enters.

 

[psneeld]

Thanks Forkliftt!

 

[FF]

On many units there is a built in time delay that does not allow the compressor to start iinstantly.

This delay allows the gas pressure to unload , so the starting amps do not go thru the roof.

FF

 

[Eastcoaster]

I believe it might be a faulty High Pressure switch. Check the switch after the compressor has stopped. If it is open, The switch has tripped. The switch range should be marked on it. It would then be necessary to check the High side Pressure to determine if it is going off on high pressure or if the switch is faulty. When checking the high pressure it should be within the range of the High pressure switch.
Just My nickel..... (inflation you know.....)

 

[Gulfstar 36]

I have a split system like this (Crusair) from 1982 or so. It was only giving heat so I disconnected the reversing valve till I got around to replacing this controller for about 80 bucks. My schematic was under the access panel. 30 years old and still chillin!

 

[psneeld]

Thanks guys...keep it coming...might have time to dig into it this week...thanks again!

 

[Eastcoaster]

I have a split system like this (Crusair) from 1982 or so. It was only giving heat so I disconnected the reversing valve till I got around to replacing this controller for about 80 bucks. My schematic was under the access panel. 30 years old and still chillin!

They are good units. And easy to work on and service.

 

[Forkliftt]

Update for psneeld

I just checked my rotary dial for the thermostat that I mentioned earlier in the post and the access hole is in the REAR of the switch. Not the front see pic.

 

[Underway]

The forum at marine-ac.com has a good discussion of issues encountered with these older units...

 

[ben2go]

The forum at marine-ac.com has a good discussion of issues encountered with these older units...

Thanks for that site.

 

[Gulfstar 36]

The pullout from my old cruisair has this as well. Might have fixed my issue but I figured it was on borrowed time at 30 years old. Note Mine was pop riveted in and I have to pop rivet the new one in as well because when I tried to use screws the screw head interfered with the knob.

I just checked my rotary dial for the thermostat that I mentioned earlier in the post and the access hole is in the REAR of the switch. Not the front see pic.