Community Forums

4point · 05-10-2010, 07:41 AM

I have a 2 way fridge/freezer that is close to completely not working. It does not work in Auto (120V) and works intermittently in Gas mode. It doesn't even sense that the 120V is present when its available. I did a little research on the webs and found that a Dinosaur Micro P711 module may be needed. Can anyone verify this?

Fridge:
Dometic # RM 2611, Gas/Electric 2 way

Thanks in advance
Rob

Gary RVRoamer · 05-10-2010, 07:59 AM

Have you checked the obvious, like making sure there is 120v power on the receptacle the fridge is plugged into? Can't sense 120v if it's not there...

Intermittent gas mode operation could be many things. Would need to hear more about the symptoms before concluding that a board replacement is needed. That's about the last thing to do. Does it light? Run a few seconds and go out? If it does light and run, does the fridge cool ok?

4point · 05-10-2010, 08:16 AM

I have checked and verified voltage, the trailer is level. It will run in gas mode anywhere from a couple minutes to a couple hours. It does get cold and the freezer does freeze. The "Check" light always comes on when it quits. I have the unit set to "Auto" and have only seen it sense 120V once for a few seconds and go out. It only did that once in all my attempts to get it going. "Auto" and "Gas" are my only two settings avilable on this unit.

GaryKD · 05-10-2010, 12:49 PM

Hi 4point,
How about trying some cheap and easy fixes first? Take the cover off the control board and remove and reinstall all the connections. Make sure there is a good connection and no corrosion. Take a look at all the fuses. There may be more than one on the control board. Even if the fuses check out good replace them (another long story). Make sure the fuse holder is free from corrosion. Let us know what you find.

4point · 05-10-2010, 03:30 PM

Thanks Gary, yes I did all that yesterday. I have the day off today so I'm trying to get to the bottom of this issue. I'm using an Fluke 87IIITRMS meter to do all electrical checks.
I just checked:
1. Ran electronic diagnostic check on the upper controls board. It checks out good.

2. The 120V Heating element reads closed. Supposed to read 48ohms.

3. Did not check the thermistor because of not knowing how to remove it.

4. Gas solenoid valve works great. Opens and closes when called for.

5. Igniter work great. Lights flame every time.

6. AC voltage is present on terms J5 and J6. (line in)

7. AC voltage is NOT present on terms J7 and J8. (120V Heater)

8. All fuses are new and good.

9. Thermocouple reads 16-19mv. Spec is 25-35mv. Could be the cause of poor gas operation.

10. Burner has been cleaned and is good.

11. Orifice has been cleaned and is good.

12. Flue has been cleaned and is good.

13. Ventilation is good and unobstructed.

All thoughts on this are welcome..........

GaryKD · 05-10-2010, 04:27 PM

Hi 4point,
If I were you, the control board is next for replacement. Darn good diagnostics. Are you an engineer (I'm a retired one)?

Before replacing the thermo couple, recheck the 12 VDC power. Make sure it is 12.5 VDC or higher. If this is true, the thermo couple is on the block for replacement.

4point · 05-10-2010, 07:18 PM

Quote:

Originally Posted by GaryKD

Hi 4point,
If I were you, the control board is next for replacement. Darn good diagnostics. Are you an engineer (I'm a retired one)?

Before replacing the thermo couple, recheck the 12 VDC power. Make sure it is 12.5 VDC or higher. If this is true, the thermo couple is on the block for replacement.

Thanks again Gary! DC voltage is good. Its all been charging for several days and is still plugged in.

No, no engineer here. Just an old electrician with mad troubleshooting skills.

Thanks for the direction.

Robs · 05-10-2010, 09:36 PM

1. Ran electronic diagnostic check on the upper controls board. It checks out good.
2. The 120V Heating element reads closed. Supposed to read 48ohms.

48ohms is correct for your model you need to replace the element.

3. Did not check the thermistor because of not knowing how to remove it.

Disconnect the thermistor harness from the P2, 2-pin terminal on the lower circuit board. Place the thermistor in a glass of ice water, approximately 33°F to 35°F. Wait 2 to 3 minutes. You should get a reading of approximately 7,000 to 10,000 ohms.

4. Gas solenoid valve works great. Opens and closes when called for.
5. Igniter work great. Lights flame every time.
6. AC voltage is present on terms J5 and J6. (line in)
7. AC voltage is NOT present on terms J7 and J8. (120V Heater)

No voltage at the heating element connection terminals J7 and J8 on the circuit board. If no voltage is present, check the 5 amp AC and 3 amp DC fuses. The 3 amp DC fuse is designed to protect the circuit board from internal shorts. The 5 amp AC fuse is designed to protect the integrity of the AC heater circuit from shorts.

8. All fuses are new and good.
9. Thermocouple reads 16-19mv. Spec is 25-35mv. Could be the cause of poor gas operation.

The thermocouple should produce 25 to 35 millivolts when connected to the lower circuit board. Any reading below 18 millivolts could cause erratic gas operation.

10. Burner has been cleaned and is good.
11. Orifice has been cleaned and is good.
12. Flue has been cleaned and is good.
13. Ventilation is good and unobstructed.

I would replace the element and the thermocouple before considering changing the board.

Rob