Isotherm Fridge Help

[Slip Away]

We just got a new to us boat. It has an Isotherm AC/DC fridge. I believe it is a Cruise model CR65, with Danfoss compressor. The fridge does not cool, it seems the compressor is not starting. The Fan runs, the light inside is on when door is opened. AC and DC breakers are on, new batteries in the boat, and is currently hooked up to shore power. I pulled the fridge out and checked the connections and everything looks to be hooked up correctly. Just two DC wires to the power converter, and AC plugged into an outlet.
No matter where we move the thermostat, it does not start the compressor and will not get cold.
One thing I noticed, is when I turn off the AC breaker at the panel, and turn on the DC breaker, the light in the fridge goes dim. It is on, but barely.

Any ideas what might be wrong, and what else to check ? I am not an electrical guy and not sure where to look.

I appreciate any help.

Thanks

 

[The Great Escape II]

Re: Isotherm Fridge Help

Call Isotherm, their customer support is great. Mine is 5 years old and the latch to the door broke, they sent me a new door (stainless steel by the way).

 

[Fireman431]

Re: Isotherm Fridge Help

Don't quote me on it, but it sounds like the power module is bad. I have a troubleshooting matrix to follow, but it's on the home computer. After I get back, I'll look into finding it and posting on the site for you.

You'll need a jumper wire, a multimeter, and a test light. Pretty simple. The power module for mine was around 125.00. Much cheaper than a new fridge, though.

 

[Slip Away]

Re: Isotherm Fridge Help

Thanks Fireman. My research so far is leaning towards the power module as well. I was going to use a jump wire to see if the thermostat is shot first.
That would eliminate one possibility at least. Those compressors are pretty stout, so that might be least likely to fail. Low on R134 is probably a slim possibility.

I'll be looking for your post and try your method.

Thanks so much.

 

[Fireman431]

Re: Isotherm Fridge Help

OK...This is a wall of text, but it's pretty simple. Just follow the steps and it should isolate the problem. I tried it and it worked great.

Trouble-Shooting Guide​

1) Turn power on and turn thermostat to "7" position (Go to #2)

2) Is the compressor running? (put your hand on top to feel slight vibration to be sure). If Yes-Go to #14. If No-Go to #3

3) Is the DC Breaker is in the "on" position & optional fuse is good?
If Yes-Go to #5 If No-Go to #4

4) Replace fuse if bad or turn breaker "on". Does fuse or breaker blow?
If Yes-Go to #6 If No-Go to #5

5) Check voltage at the refrigerator "+" & "-" terminals on the black module. Is it over 12 VDC? If Yes-Go to #7 If No-Go to #6 - (Go to 17 on AC/DC models)

6) Check batteries, wiring and connections to the refrigerator for fault, corrosion, proper wire sizing and correct the problem. Go back to #1

7) Put a jumper wire between terminals "C" & "T". Is the compressor running now? If Yes-Go to #11 If no-Go to #8

8) Disconnect power. Remove electronic module (philips screw beside terminal designation label will require removal). Disconnect the plug. Measure resistance (ohms) between each of the three compressor terminal pins. Is the measured resistance APPROXIMATELY the same?
If Yes-Go to #9 If No-Go to #10

9) Replace Electronic Module. Go back to #1

10) Have compressor replaced by qualified appliance technician who has the ability to evacuate and recharge the system. This is seldom necessary so please be sure and if possible contact manufacturer for further instruction beforehand.

11) Check wiring to thermostat with ohm meter to ensure there is continuity. (No broken or damaged wires or connectors). Is the wiring okay?
If Yes-Go to #13 If No-Go to #12

12) Disconnect power. Repair or replace wiring as necessary. Go back to #1

13) Replace thermostat. Go back to #1

14) Is the fan running? If Yes-Go to #16 If No-Go to #19

15) Provide extra ventilation (ie. hatch open, Lazerette open - where air can escape). After an hour is it refrigerating?
If Yes-Go to #16 If No-Go to #19

16) Maintain that adequate ventilation has been provided. Add ventilation as required.

17) Have a qualified appliance technician determine if there is a refrigerant leak or a compressor with a mechanical problem.

18) Check voltage at "+" and "F" terminals. Is there 12 VDC (or 24 VDC)?
If Yes-Go to #19 If No-Go to #5

19) Replace fan.


From 20 to 27 Applies to AC/DC Modles Only!

20) Switch DC breaker off and AC breaker on. Does the refrigerator run?
If Yes-Go to #18 If No-Go to #19

21) Turn DC breaker on and check DC voltage on Terminal Block located on side of grey AC power supply. Is it above 12 VDC (or 24VDC)?
If Yes-Go to #24 If No-Go to #6

22) Check fuse on grey AC power supply (4 amp 110V and 2 amp 220V). Is the fuse good? If Yes-Go to #22 If No-Go to #20

23) Remove power supply and determine if there are any indications of a short circuit. If no, replace fuse. Does fuse blow again?
If Yes-Go to #24 If No-Go to #21

24) Check DC voltage output of power supply at black module terminals "+" & "-". Is it above 12 VDC (or 24 VDC)? If Yes-Go to #18 If No-Go to #24

25) Is 110V (or 220V) available at the AC plug?
If Yes-Go to #21 If No-Go to #23

26) Check plug, wiring, breaker, shore power or genset for damage or fault. Repair or replace as required. Go to #17

27) Replace grey AC power supply.


I hope this helps. If not, I'm sure there are a bunch of vendors that will be willing to sell you a new fridge.

If it is the power module, let me know. i'll send you the link of where I got mine (if it's not available here on iboats). 3 days for shipping and it was here.

You might want this as well...

 

[Slip Away]

Re: Isotherm Fridge Help

Thanks so much. The guide is easy enough to understand, that I think I can follow it. I will give it a try this weekend and see what I find.

 

[Slip Away]

Re: Isotherm Fridge Help

After testing per the trouble shooting guide, we found that the fan works, compressor turns on, thermostat works, power module works, and all works on AC or DC power. So, I will have the compressor checked for any leaks , and then a re-charge. Hopefully that will take care of it.

 

[Slip Away]

Re: Isotherm Fridge Help

NOT!!!
Evaporator had a hole in it from previous owner chipping ice. Patched the hole. Charged system. It holds R134 and temp for about two hours only.
There is moisture in the oil in the compressor. Only way to fix (maybe) is drain the compressor of oil, replace with new ($100 per gallon) reassemble and re-charge. The service manager does not recommend I have it done.
6 hours labor, oil etc, that puts the repair cost very close to a new fridge.
So, cooler and ice in our new boat this season. Maybe next year replace the fridge. Not happy with this. I think it should have been caught at the survey, but we would have had to pay to fix it then too. Could be worse I suppose.

 

[Fireman431]

Re: Isotherm Fridge Help

Well, sorry for the crappy luck, but at least you got it figured out.

Check local Craigs List ads also. I found a fridge here in Central Florida for 300.00. I almost wished I needed it because it was such a good deal.

I'm not sure where you are, but let me know if you want the link. i can send it to you.