RAMPY
South Florida
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Joined: 03/12/2003
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My 2 low profile Duo-Therm Penguin A/C units on my 2004 DutchStar have been working great....until today. I had both running when the rear unit "decided" to emit hot air (just as you would expect if it was in Heat Pump Mode. The Duo-Therm Comfort Control unit (5-button)appeared normal, i.e both Zones indicated "cool".
So, I shut down both units, waited 10 minutes and restarted just the rear unit. I started it in "vent" mode (high) and it seemed fine, so I went to "cool" mode (with a low temp setting)and waited. After a minute or so the compressor kicked in normally and cold air was coming out. However, after 5 or more minutes the "mystery" occurred again...hot air (definitely not what you would expect from just the fan running).
So I shut it down, started the forward a/c and it is working perfectly.
Any ideas??? The a/c voltage in this CG is excellent & my filters are clean.
Jack and Mary
2004 DSDP (4010)
2012 Honda CRV
Falcon and BrakeBuddy
FMCA:F337928
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The Texan
Meridian, Idaho
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Joined: 01/16/2004
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Try a full reset on the thermostat. That seems to cure many problems with the Dometic AC's
Bob & Betsy(FishNFanatic) - USN Aviation Ret'd '78 & LEO Ret'd '03 & "Oath Keeper Forever"
'05 HR Endeavor 40PRQ, 400 Cummins-Pulling our '11 Silverado LT, Ex Cab 6.2L NHT 4x4, w/2010 Rzr or 01 V Star in back.
Where the wheels are stopped today
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dougrainer
Carrolton, Texas
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The Texan wrote:Try a full reset on the thermostat. That seems to cure many problems with the Dometic AC's
Resets for Dometic CCC tstats do NOTHING for operational problems. ALL it does is verify the DIP settings on each AC control board. The OP's problem is a defective reversing valve coil. Just replace the reversing valve coil, NOT the reversing valve as it is not a replaceable part. Doug
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sljkansas
Miami Co. Kansas
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Joined: 09/28/2005
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Is it iceing up? Check the fins on the AC coil, they could be plugged up.
Steve & Linda
Son married (1 DIL, 3 granddaughters 1 grandson)
Daughter can now be called a Teacher.
Miami Co. Kansas
2004 F350 CC dually 8ft bed 6.0 PSD
2009 Bighorn 3670RL
B&W under bed hitch with 18k companion hitch
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sailor_lou
Connecticut
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IIRC there is a solenoid that energizes in the A/C mode to direct the refrigerant flow for cooling and is de-energized in the heating mode. If you do not have an icing issue, perhaps there is a problem with the solenoid dropping out after it is energized for awhile. I'll check my shop manual to ensure I'm not giving you incorrect info. Good luck.
Lou
05 Travel Supreme Envoy
Good thing I checked, it appears it can be configured either way. From the Tech. Manual:
C13. Reversing Valve
The reversing valve is the heart of the heat pump. It directs
refrigerant flow to the coils to achieve proper direction of
flow that allows the same system to supply heated or cooled
air to enter the inside atmosphere of the structure according
to occupants desires.
The reversing valve's solenoid can be energized in either
HEAT or COOL mode of operation. Most Duo-Therm Heat
Pumps have the solenoid energized in the COOL mode of
operation. The Dual (Model 39424) has the solenoid energized
in the HEAT mode of operation. See FIG. C19. The
solenoid on the reversing valve can be loose, this will cause
a humming noise during the off cycle; especially is the
blower shuts off with the compressor. Check the screw
holding the solenoid coil on the reversing valve for tightness.
One way to check the reversing valve is to feel the refrigerant
line at the top of the inside coil. In the COOL mode, this
line will be cool or cold to the touch. In the HEAT mode, this
line will be warm or hot to the touch. If you do not achieve
these results, direction of refrigerant flow is not correct.
The ohms resistance of the reversing valve solenoid coil is
approximately 465 ohms plus or minus (±) 10%. If ohms
reading is within this range, the solenoid coil is good. If
ohms reading is outside this range, replace the solenoid
coil.
On Model 39424, verify AC volts are to the solenoid coil
when in HEAT mode. If AC volts are NOT present, verify
wiring is correct, especially to the 9-pin terminal connector.
Check that the connection is completed through it. Next,
verify power module board and the relay are good. If AC
volts are present and solenoid coil is good, but refrigerant
flow is not proper, the reversing valve assembly needs to
be replaced.
On all other models verify AC volts to the solenoid coil when
in COOL mode. If AC voltage is NOT present, verify wiring
is correct, especially to the 6-pin terminal connector. Check
that the connection is completed through it. Next, verify
power module board is correct, then verify relay is correct.
If AC volts are present and solenoid coil is good, but the
refrigerant flow is not proper, the reversing valve assembly
needs to be replaced.
* This post was
edited 05/17/12 02:38pm by sailor_lou *
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dougrainer
Carrolton, Texas
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Icing????? Are you kidding me??????? He states it runs for less than 10 minutes and then blows hot air. NO WAY it could ice. And Icing is NOT going to cause Heat output. The 5 button CCC Dometic heat pumps the DEFAULT is HEAT and it takes the coil to be energized to cool. It is common for a defective coil to drop out within a few minutes or not activate at all. On the NEW 12 button CCC Dometic the default is COLD and it take the Reversing coil to be energized to get in Heat mode. The OP has a older 5 button CCC control system. Doug
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RAMPY
South Florida
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Thanks for the feedback...I'll give some a try tomorrow.
I'll try a reset on the thermostat (luckily, I have notes on how to do that). I doubt that icing is a problem because the situation just occurred again within 5 minutes after a 10 hour shut down. Sailor Lou's thoughts seem to be on target but I'm not sure I can handle the diagnosis....so, I will be taking his notes with me when I go to my RV service folks.
I'll be sure to let you know what the end results is.....thanks, Jack
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Diplomat Don
Moorpark, Ca
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Joined: 04/09/2005
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Rampy......"sailor_lou" gave you the correct info. I had the same issues (identical) last year. The heat pump units default to the heat mode. The reversing valve has to "reverse" to operate in A/C mode. When it quits working, it stays in heat mode. The repair is very simple. Remove the shroud and the first thing you see on top of the unit is the reversing valve sitting atop the freon tubing. The wires run from the valve to the other side where the start capacitors are located. Be VERY careful when changing out the wires. The capacitor will hold a charge.
When I replaced mine, I went online to PPL Motors with the model number of my A/C unit. It takes several pages to get to their parts page. PPL Motors. I ordered the reversing valve and the large start capacitor. I replaced the capacitor since I had the unit open and it was pinched/crushed by the mounting bracket.
PM me if you need any more info.
Don & Mary 
2005 Monaco Diplomat 36SKT
400 Cummins 
2012 Chevrolet Silverado LTZ CrewCab 4WD
2013 Polaris RZR 800 LE
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katysdad
Virginia
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Joined: 08/03/2010
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what doug said
Dodge Ram 3500 DRW Diesel
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RV-1/2n-FUN
FL.
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Joined: 03/30/2003
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THANKS sailor-lou and dougrainer. I must have the 12 button since mine defaulted to cool.
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