Heat Pump Compressor Died? - FIXED

[Scotty Hutto]

All,

Just wanted to share a recent experience with my Penguin Duo-Therm heat pumps that might help someone else...

My heat pump compressor stopped operating last weekend.  I went through a quick trouble-shooting process and determined that my start capacitor was bad, so I replaced the start cap.  No joy - the compressor still didn't run. 

Pulled out the Dometic Heat Pump troubleshooting manual (available in the files section) and went through the process of checking everything with my multi-meter and couldn't find a problem.  compressor, caps, relays... everything tested fine, but the heat pump compressor wouldn't run.

At this point, and because I have 15+ year old heat pumps, I started thinking I needed to order two new Pengiun II units to the tune of $3,000 (give or take taxes, shipping, etc.) and just replace everything.

But... I decided to go back and check the wiring one more time, and found that the run wire (blue wire in my unit) to the compressor had fallen out of the little "holder", had fallen on the axle of the fan, and been cut in two.  For a short-term fix, I found some similar gauge wire and spliced it in place. Everything works fine now.  For a long term fix, I will completely replace the wire once I get a chance, so that I don't have a splice.

Just a reminder that:

1. Sometimes its the simple things that trip us up, and

2. Next time you have the cover off your AC or heat pump, put a $0.10 zip tie on the wiring so you don't suffer a similar fate. 

Scotty

[Trinidaddave]

Thanks Scotty, you saved some $$ this time 

[Corgidad]

Scotty, last night heat pump quit blowing hot air and today AC did not blow cold, fans working in all speeds. I have the same Duo-Therms as you. I will get on the roof tomorrow and start troubleshooting but would love to see the file that you referenced in your post. I can not find it anywhere would you be so kind as to guide me in the right direction. Before you changed the start capacitor did you check it meter or was there visible damage that made you think it was your problem. Thanks in advance, Mike ( from Grand Oaks)

[96 EVO]

Mike, don't know if you will be so lucky, but, when one of my start capacitors and HTCP(?) blew, it was very obvious just looking at them!

[Flyinhy]

Something similar happened to me yesterday. My bedroom unit quit working. I took the cover off and I could smell something burnt. The fan motor went bad. I can spin it and it will start working. I completely unhooked the wires from the junction box. I've tried to use the furnace with the motorhome on shore power but the vents never blow hot air. I took the cover off the aqua hot and I have hot water coming out and I can hear the circulation pumps working but that's about where I had to stop today.....more rain and cold weather coming through. Thank goodness I still have 2 more units on the roof that are still working. Good to hear your fix was simple and easy.....

[Ivan K]

I'd say that if you can spin the fan shaft and it runs, you need a new capacitor. With the AH, if you don't feel hot fluid in the outlet hose to effected zone, knock on the check valve above outlet of that zone pump to unstuck it. Stay warm.

[Scotty Hutto]

Here’s the service / troubleshooting manual @Frank McElroy Can you make sure this is in the files  

Duo-Therm AC Heat Pump Service Manual.pdf

 

 

[Scotty Hutto]

Also, there is a procedure in that manual to check the capacitor with an multimeter. I used that procedure to check my caps. 

[Frank McElroy]

7 hours ago, Scotty Hutto said:

Here’s the service / troubleshooting manual @Frank McElroy Can you make sure this is in the files  

Duo-Therm AC Heat Pump Service Manual.pdf 2.79 MB · 6 downloads

Yes this document is in the download files.  It was added over a year ago.

 

 

[Flyinhy]

10 hours ago, Ivan K said:

I'd say that if you can spin the fan shaft and it runs, you need a new capacitor. With the AH, if you don't feel hot fluid in the outlet hose to effected zone, knock on the check valve above outlet of that zone pump to unstuck it. Stay warm.

Unstuck it.....lol. love it 😀!! I'm gonna give it a shot. I know the whole system needs a good going through. 

8 hours ago, Scotty Hutto said:

Also, there is a procedure in that manual to check the capacitor with an ohm meter. I used that procedure to check my caps. 

I hope that's all that's wrong with it. In the last 2 months I've spent quite a large amount of money......I'll have to sell my corvette if this keeps going. 😆 

[Scotty Hutto]

1 hour ago, Flyinhy said:

...I'll have to sell my corvette if this keeps going. 😆 

Well, new caps are less than an oil change for your ‘Vette, so here’s hoping that fixes it!

[Trinidaddave]

Using a OHM meter to check a capacitor doesn’t provide any value to your troubleshooting the capacitor.  It just shows it can be charged and discharged, but doesn’t prove the capacitor is not failing.

the best way to check a capacitor is to use a multi- meter that reads capacitance in micro farads or use a capacitor checker.

Another proven method is to read the amperage of the start winding at the capacitor HERM or hermitic terminal on the capacitor multiply by the constant 2652, then divide by the voltage measured between common terminal and HERM terminal.

AMPERAGE X 2652 divided by VOLTAGE

this should  match the rating on the side of the capacitor. The system must be operating to use this method.

[Corgidad]

David my multi meter does not read micro farads so I just took the start capacitor out of my rear unit and put it in the front unit but no luck, still don't have hot or cold air just the fan on all speeds. Also put the front Capacitor which I though was bad in the rear unit and it worked perfectly. So its not the start capacitor. Did not see any visible signs of Freon leak either. Scotty not my luck to find a severed wire all of mine are in tack. Will do more troubleshooting tomorrow but if anyone else has any suggestions I have open ears. Thanks everyone.

[Ivan K]

As I understand, the fan is running fine but the compressor may or may not run. Do you hear or feel it kick in? If you hold your hand on it when it should start, you would feel it starting. If it does run, you may be out of freon and that would need a tap to know for sure what's going on.

[Corgidad]

Ivan, thanks for the reply. There is a noise which sounds like the compressor starting but not as pronounced as usual. I have a friend who has everything to check the freon but he is out of town until Monday. I will have help tomorrow so I can stay on the roof while they turn the AC on inside. Just glad its not the middle of summer here in Florida.

[Flyinhy]

Thanks guys. I got 2 heat zones working on the furnace so far. I had to prime the pumps and unstick the check valves. This sucker almost runs me out of the coach it's so warm!!! This gives me a little more time to dive into the heat pumps on the roof. Funny thing is the front zone fans were working fine on the furnace before I started working on it but now....no fans at all. I'm still happy though.....2 working is fantastic!

[throgmartin]

My bedroom AC unit gave up the ghost a month ago. It took that long to get one of my techs here to check it out ( there is no benefit to owning an RV service company. I still have to wait in line for service 🙂

Turns out the AC unit blew its charge. The downside ? It is a brand new penguin II. The Upside ? It is still under warranty. I have been advised by my director that despite being the owner of the service company I have to go to the back of the line and wait to have it replaced. I have no travel plans so I wont pull rank and demand it is fixed immediately. 🙂

[Hypoxia]

36 minutes ago, throgmartin said:

My bedroom AC unit gave up the ghost a month ago. It took that long to get one of my techs here to check it out ( there is no benefit to owning an RV service company. I still have to wait in line for service 🙂

Turns out the AC unit blew its charge. The downside ? It is a brand new penguin II. The Upside ? It is still under warranty. I have been advised by my director that despite being the owner of the service company I have to go to the back of the line and wait to have it replaced. I have no travel plans so I wont pull rank and demand it is fixed immediately. 🙂

Curious what was the leak?  How long is the wait?  Most of the time I would fix it myself rather than wait, especially in the summertime.

[Corgidad]

Good thinking Chris, its always best to keep the Boss happy.😀

[96 EVO]

5 hours ago, throgmartin said:

 

Turns out the AC unit blew its charge. The downside ? It is a brand new penguin II. The Upside ? It is still under warranty. 

Really sounds like the quality of these appliances has gone downhill in the last several years 😕!

[Scotty Hutto]

On 11/26/2021 at 9:50 AM, Trinidaddave said:

Using a OHM meter to check a capacitor doesn’t provide any value to your troubleshooting the capacitor.  It just shows it can be charged and discharged, but doesn’t prove the capacitor is not failing.

the best way to check a capacitor is to use a multi- meter that reads capacitance in micro farads or use a capacitor checker.

Another proven method is to read the amperage of the start winding at the capacitor HERM or hermitic terminal on the capacitor multiply by the constant 2652, then divide by the voltage measured between common terminal and HERM terminal.

AMPERAGE X 2652 divided by VOLTAGE

this should  match the rating on the side of the capacitor. The system must be operating to use this method.

You are correct!  I should have said multi-meter, not ohm meter! 🤦🏻‍♂️

[woodylmiller]

Good timing on this post.  My heat pumps, 3 of them, are not working.  They all worked back at the house, of course.  Currently in sunny southern CA for the winter so not a big deal.  AH is working fine for heat if we need it.  A/C's are working on all 3.  This suggests to me a control issue.  Have not gone into the schematics yet, so not sure of an interconnect permissive for all 3, but maybe so.  Does anyone have first hand knowledge that there might be a "central" control that would not allow the 3 heat pumps to not work?  Nothing on "heat pump" works, no fan, nothing.  Before going up on the roof and shouting obscenities at the dog, am I thinking right about some sort of central control that is effecting the 3 heat pumps?  Maybe the original 5 button DuoTherm thermostat???  Thanks,

Woody Miller

09 Dynasty

[Ivan K]

I believe that if you have multiple roof units on the same thermostat, they all would have to be set to heat pump to work. It does not like to have one set to cool and the other one to heat. At least on ours.

[96 EVO]

You can't have any of the other zones set to 'furnace' either. 

Other zones need to be Off, Fan, or Heat Pump.

[woodylmiller]

OK, I'll give that I try, just setting all to heat pump and see what happens.  Thanks,

Woody Miller