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Topic: Heat Pump Run Amok (Read 567 times) previous topic - next topic

Heat Pump Run Amok

Before going to bed set front AC to 75 degrees.  Woke at 3:30am and feeling a little warm.  Went to check thermostat and front of coach really warm.  Front AC was blowing very hot air, like the heat pump was on.  I think I remember on my 03 the same thing happened and I replaced the reversing valve solenoid.  The unit is 21 years old, and lately, when unit shuts off, water drips from ceiling panel (can't think of proper term for interior cover).  I had all units checked and serviced (clean coils) a week ago.  Since then have noticed rear AC dripping water after shutting off.  Thought, ideas or recommendations?
Bill and Joyce, The House2 and Dashboard Pig III
2000 U320 4210 CAI (The House2)
Build # 5733
2019 F150 King Ranch FX4

Re: Heat Pump Run Amok

Reply #1 –
Quote from: Bill B –
I had all units checked and serviced (clean coils) a week ago.  Since then have noticed rear AC dripping water after shutting off.  Thought, ideas or recommendations?

My first thought:  Don't go back to whatever shop checked and cleaned the coils?

What make/model roof units on your coach?

What was outside air temp when you woke to warm air blowing out of unit?

Does your fan blow all the time unit is on, and the compressor cycles on and off to control set temp?  Or do the fan and compressor simultaneously cycle on and off to control temp?

Get up on the roof, pull the covers off, check the drain holes to make sure they are open.  If they are plugged, condensate will accumulate in the pan and eventually find a way to drip on your head.

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Heat Pump Run Amok

Reply #2 –
Mine iced up once and blew ambient air instead of chilled air. The fact you are getting condensation could stop the cooling if that happened but would not make heat.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Heat Pump Run Amok

Reply #3 –
Chuck, the technician did what I ask him to do.  He cleaned the coils and drains, as well as a general look see for obvious problems. The units were working well at that time with the exception of the front ac dripping water.     
The units I have are the original Dometic Penguin units.  The outside air temp was 78 to 80 degrees and humid, as it always is here.  The water dripping problem started when our temps and humidity started climbing about a month ago. 
I usually have the fan set to auto so the fan and compressor shut off at the same time.  Leaving the fan on would probably be better in the humid conditions. 
I was on the roof when the tech cleared the drains for all the ac units so no restrictions there.
Could be possible that a leak in the cover for the evaporator coil could allow warm air to leak in and result in lots of condensation that overwhelms the drain lines. 
I have been running the front air since about 7 this morning and it is cooling fine.  Will set fan to stay on and see what happens. 
Bill and Joyce, The House2 and Dashboard Pig III
2000 U320 4210 CAI (The House2)
Build # 5733
2019 F150 King Ranch FX4

Re: Heat Pump Run Amok

Reply #4 –
Bill,

We had the original Dometic Penguins on our coach when we bought it.  (They have since been replaced)  The ones on our coach may have been different than your later model Penguins.  Our old Penguins were not "heat pumps".  They were conventional air conditioners with auxiliary electric resistance heating coils for the "heat" function.  I don't know if that is true for your units.  Our old Penguins had to be manually set to the "heat" function to activate the coils.  There was no possible malfunction that would allow them to switch from cooling to heating on their own.

I was originally thinking that when you woke to warm air blowing, perhaps the compressor was off and the fan was just blowing warm outside air.  But it seems, from what you have just stated, that was not the case.  Unfortunately, ! cannot offer any other explanation for the "warm air blowing" episode.

As for the water dripping, I did have that problem (with our rear unit) and went through a long period of trouble shooting before I discovered the cause.  Link below to my posts covering that adventure.  The problem I finally found would not be apparent to even a qualified technician who was doing a routine inspection/cleaning of the air conditioning unit.

Penguin A/C Water Drip Fix

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Heat Pump Run Amok

Reply #5 –
Thanks Chuck, that was very helpful.  First chance I will get on roof and check that out.  The other issue, I feel that the unit definitely went into heat pump mode as compressor was running and the air was very hot but thermostat said it in cool mode.  Same as years ago with my other coach and I replaced the control board and reversing solenoid to fix.  I'm wondering if, considering cost of repair and the age of the unit if I should just replace.  All 3 units are original.  I guess regarding that, I'm looking for opinions.
Bill and Joyce, The House2 and Dashboard Pig III
2000 U320 4210 CAI (The House2)
Build # 5733
2019 F150 King Ranch FX4

Re: Heat Pump Run Amok

Reply #6 –
My opinion, FWIW.

I feel it is worthwhile replace a still working but ancient unit with a newer and hopefully more reliable and energy efficient unit.  Sadly, these days "newer" does not always equate to "more reliable".

I prefer to schedule major projects at a convenient time and place of my choosing, rather than having to make emergency repairs on the road.

So, that is what we did:

New Air Conditioners

We have had our Atwood's for 2 years now, and so far zero problems.  We run the A/C units every day in the summer, whether we are on the road or the coach is parked at home in our driveway.  We use our coach like an extension room of our house, with the residential fridge always fully stocked, so we like to keep it cool in the summer (and warm in the winter).  The Atwoods have had no problem keeping it at 74 degrees inside, even when the coach sits out unprotected in 110+ degree West TX heat.

So far, we are happy with our decision to upgrade the cooling units.

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Heat Pump Run Amok

Reply #7 –
Thanks Chuck, I agree.  Better on my own terms if possible. 
Bill and Joyce, The House2 and Dashboard Pig III
2000 U320 4210 CAI (The House2)
Build # 5733
2019 F150 King Ranch FX4

Re: Heat Pump Run Amok

Reply #8 –
I had the same thing happen on our coach and when I replaced the coil and circuit board that fixed it. 
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Heat Pump Run Amok

Reply #9 –
Quote from: Bill B –
Thanks Chuck, I agree.  Better on my own terms if possible. 
Had pretty much the same scenario.  Cold air blowing when I left coach overnight and warm when I checked back the next morning.  Had it happen on the way home from a trip about a month ago.  Ordered 2 new penguins from local shop with thermostat yesterday and they installed them today, 2 hours labor @ $95and out the door, seem to work well on the 90f- 1 hr ride home. $1400 for each unit $150 for thermostat.  Doesn't even hurt if you say it real fast!  They had to go, momma don't like a hot trip!

2000 GV320 4010 build #5712  2019-?
1999 Bounder 2000-2008
Bardstown, KY
🥃The Bourbon Capital of the World🥃

Re: Heat Pump Run Amok

Reply #10 –
Sorry you are having a reversing valve problem. Voltage usually keeps the reversing valve in one position and no voltage lets it change to the other position. How about finding out which is which and either put your own voltage to valve or preventing voltage from reaching valve to keep in in A/C mode.

BTW, We are not ever in favor of RV roof heat pumps. Without heat pump, all compressor refrigerant lines are completely sealed often going leak-free for 20-30 years. With heat pump a moveable valve is installed in the lines. Heat rises so floors do not receive max heat, so roof airs are not the best heater. Roof air units can 'wear out' over the years from use. Only roof airs can cool, but different floor level devices can heat, so why wear out roof units for heat.

So given a choice we prefer cooling-only roof air conditioners. Home heat pumps are a different situation.

Re: Heat Pump Run Amok

Reply #11 –
Leaving the fan on low or high instead of auto seems to help a little with the dripping water.  Haven't had another reversing valve issue yet.  I am inclined, considering the age of the units and my limited ability to repair, to go the Tommy D route and replace them.  However, I am somewhat interested in the Furrion units.  And if I read the web site correctly, the Furrion is compatible with Dometic.  Both Dometic and Furrion are made in China I believe so can't expect them to last as long as the ones on my coach now.  But at almost 70 years, I may not need them to!  I agree with the AC only install.  I have only ran the heat pumps every couple years to make sure they still work.  I'm very appreciative of all the advice and opinions!
Bill and Joyce, The House2 and Dashboard Pig III
2000 U320 4210 CAI (The House2)
Build # 5733
2019 F150 King Ranch FX4

Re: Heat Pump Run Amok

Reply #12 –
Bill,

AC only was 2 weeks out for me and was what I wanted but had to go with HP for quicker turnaround.

2000 GV320 4010 build #5712  2019-?
1999 Bounder 2000-2008
Bardstown, KY
🥃The Bourbon Capital of the World🥃

Re: Heat Pump Run Amok

Reply #13 –
 Reply # 10 (cooling only vs heat pump cooling and heating) is a valid opinion, but there are other considerations ( ie install a unit as the replacement for the original and leave the controls alone) that can be made.

Does anybody know the model number to replace the Dometic Duo Therm AC unit model 630516321 I have in my 2003 U320 ?

I know I can call FT on Monday, but there might be a member who has done the replacement recently, Tommy D might know the answer.

Regards

Klaus
The world is not interested in the storms you encountered, but whether or not you brought in the ship.
Raul Armesto

2003 U 320 4020 Unit 6145

Re: Heat Pump Run Amok

Reply #14 –
Here you go Klaus!


2000 GV320 4010 build #5712  2019-?
1999 Bounder 2000-2008
Bardstown, KY
🥃The Bourbon Capital of the World🥃