Replacing Fridge compressor system

[Tetamanu]

Soz for any mistakes my english grammar is not what it used to be

Our fridge compressor (Frigoboat AH35F) has died on us last week after doing its best for approx 10 years. The maintanance guys said the compressor was defect after working 2 hours on it refilling the gas and vaccuuming the system etc etc. When surfing the internet i found that all the fridge producents use the same components, allways danfoss bd35 or the bd50 with or without an suitable evaporator.

So seeing the compatibility tru out those systems and our wish to upgrade i have ordered a Waeco CU94 system (based on the danfoss bd50 and suitable also for warm waters). Our evaporator is simillar to the VD21 (1100mmx270mm)
I have seen with removing the old one that i can connect the evaporator tru what is called a selfcoupling valves.


My question is:

When i connect the the evaporator does the gas automaticly run tru the systems or do i have to "Bleed" the air somewhere?
If i press the spring in the valve there is no gas escaping from it probably filled with normal air.

Thx Roy

[Richard Kollmann]

These compressors do not fail so replacing compressor may mean you will have the same trouble after replacing compressor. Is this a Frigoboat Keel cooler Model? Does Compressor run? Describe condition of how it operated.

Unless you buy from Frigoboat the line connecters will be different. There are 8 different connectors each company has their on style of connector.

[Tetamanu]

[QUOTE=Richard Kollmann;1551067]These compressors do not fail so replacing compressor may mean you will have the same trouble after replacing compressor. Is this a Frigoboat Keel cooler Model? Does Compressor run? Describe condition of how it operated.

Unless you buy from Frigoboat the line connecters will be different. There are 8 different connectors each company has their on style of connector.

Thanks for the reply, its a aircooled system AH35F i hear the compressor is running but it doesnt do the works (this after 3 years continues).
When the guys put the hoses on the system etc it didnt show any improvement while filling the compressor with gas.
Then they decided to vaccuum the system and again zero.
voltage is 13,4 and nothing changed in the boat electricly.

[Richard Kollmann]

Did Mechanic check to see what speed compressor is set to run at?

Did he tell you the amperage after compressor was running for at least 20 minutes?
After he tampered with refrigerant does compressor still run continuously and get warm?

Was there or is there now frost on any line or on evaporator?

Describe anywhere were you see frost after compressor has run for at least one hour.

BD35 at maximum Rpm of 3500 will handle a good size refrigerator unless boat is in the tropics.

[Tetamanu]

[QUOTE=Tetamanu;1551106]

Originally Posted by Richard Kollmann

These compressors do not fail so replacing compressor may mean you will have the same trouble after replacing compressor. Is this a Frigoboat Keel cooler Model? Does Compressor run? Describe condition of how it operated.

Unless you buy from Frigoboat the line connecters will be different. There are 8 different connectors each company has their on style of connector.

Thanks for the reply, its a aircooled system AH35F i hear the compressor is running but it doesnt do the works (this after 3 years continues).
When the guys put the hoses on the system etc it didnt show any improvement while filling the compressor with gas.
Then they decided to vaccuum the system and again zero.
voltage is 13,4 and nothing changed in the boat electricly.

[Tetamanu]

Hi Richard,

The compressor has a "smart device" which let you choose 120 - 160 or max cappacity he took that out of the circuit so the machine ran at max speed. It takes about 5-6 amps when on this highest speed. It does get warm but no ice forms on either the pipelines or the other parts.

Looking at youre previous reply U said these compressors do not fail so can these compressors never brake??
I did saw them using a blow heater on some of the ticker copper parts but nothing happened there either.

(It has run now btw for a 2 hours on on max freezing mode)

[Richard Kollmann]

When a compressor does not run it is told to not rum because an electrical problem exists: Boat wiring problems, Fan circuit drawing too much current or Someone has tampered with refrigerant increasing compressor starting amperage load.

When system fails to cool and compressor runs problem can vary from loss of refrigerant, to poor heart disposal, normally I find lack of repair technician experience and his tampering with refrigerant are the most troublesome problems to correct. The secret troubleshooting is in a non destructive testing process.


Yes you could use a BD 50 compressor but as far as evaporator you will need a larger evaporator with matching btu capacity including capillary tube refrigerant flow control device with equal capacity. Frigoboat evaporator may not be able to handle 500 Btu output of a BD50 compressor at +10 degrees F. This would mean Btu capacity of larger compressor would produce no more the BD35 if evaporator is not sized for BD50.

Are you saying for three years the BD35 present system was not able to maintain the temperature you wanted inside the box? Explain in detail.

Because system coefficient or performance (SCOP) can be affected in many ways a technician will look first at whether unit is installed correctly so that process heat is correctly disposed of. The quick way to see if heat is removed is to check temperature of liquid refrigerant as it mover from condenser towards evaporator, this line must be no warmer than 115 degrees F. (46 C.) If heat disposal is fair to good.

When a system is at its most efficient balance compressor will cycle On and Off less times. Smart Speed Controller devices are intended to increase compressor speed by adding resistance to thermostat wiring. Removing automatic speed controller when you think you need more capacity from system is a mistake. Without speed controller BD35 compressor will produce only 2000 Rpm and ½ output capacity compared to max speed of 3500 Rpm with speed controller connected.
Speed controller’s program is based on thermostat cycle times not actual Btu or temperature so if thermostat is not cycling at the right rate in other words cycling too often controller is confused and slows compressor down.
If speed controller is removed and you want max capacity test from compressor install a 1500 ohm resistor in thermostat wire and place a jumper wire across thermostat terminals. If unit is now working at its best amperage will be 5 to 5.5 amps in 15 minutes then slowly drop over the next 2 hours. At end of test report box temp and amperage as well as approx temperature of high pressure line after cooled by condenser.

[Calpurnius]

Hi richard, i found my old account details, so i will reply from my first one.

I have disconnected the whole unit from the evaporator and brought the device to the dealer of frigiboat in syracuse, sicily.
He will check de compressor in his lab where he has al the equipement to test these things.
In the meantime i will look for btu size from the frigoboat evaporator, i am thinking of changing that too because as you allrdy
guessed the machine never freeze even not on the highest thermostat number, and i would love to have some ice in my drinks.
I keep you updated.

[Richard Kollmann]

I do not know what the history of your system is but it sounds like you just shoot yourself in the foot and your pocket book.

Frigoboat systems are not friendly when it comes to troubleshooting a problem. My guess is you will end up with a new system. Keep us posted.