Recharge Freon on Roof Top AC

[Bill R]

Just the other day the front AC stopped cooling.    Compressor was running and I noticed that the inside temp was slowly warming up.  Started off with some cool air and then just proceeded to get warmer.  Note that it was 108F outside.  After about 1 hour the discharge vent temp was the same as intake temp.

Pulling off the AC cover and checking the unit out, all capacitors are good, relays are kicking on compressor, coils clean and no icing.  Low pressure side line was not cool and high pressure was not hot.  I put on an amp clamp on the compressor and was getting 7 amp draw.  So I am of the opinion the 401-A Freon is low. 

I did notice that there was a Schrader valve installed on the compressor low side and below it is what looks like a donut type stop leak clamp?  This must have been done by the PO of the rig.   Probably had a leak, clamped it, installed the Schrader valve, recharged and moved on.  I have attached a pic of the set up.  FYI, I took the Schrader valve cover off and quickly pushed the stem and there was nothing.  

So my plan is to recharge the system and hope the leak is slow enough to keep me going at least another 3 years plus.   Beats the current $1600 for a new Penguin II.  The unit is still in good shape and puts out nice cool air when running.

Looking for thoughts and insights?  Tips on recharging?  Tips on looking to replace that donut type clamp seal?  Other tips?

 

 

[CAT Stephen]

Bill,

 

Your A/C rooftop unit was modified by the previous owner as rooftop A/Cs have factory charged and sealed A/C systems.  The issue that you will encounter if you attempt DIY is that you can't purchase R410a refrigerant without an EPA license.  Also, truck and RV shops don't have the equipment to recharge R410a systems.  And finally, a residential A/C technician will not charge your system without a high side port to monitor the high pressure side of the system.

 

Provided that you don't have an on-board aqua hot system, I recommend that you consider the following replacement unit from RecPro (Houghton) as the cost is much lower, can be controlled from your cell phone or tablet via SwitchBot, and is much quieter:

- https://www.recpro.com/rv-air-conditioner-15k-with-heat-pump/

 

Keep in mind that the RecPro unit above does not use your existing Dometic control or the Dometic thermostat.  It has its own built in thermostat and is controlled with an included infrared remote control.  Also, you can purchase a SwitchBot hub from Amazon to remotely control the unit via your cell phone or tablet.

Edited August 21, 2023 by CAT Stephen

[Gary Cole]

1 hour ago, Bill R said:

donut type stop leak clamp

Not sure what that is. Might be a weight or rubber material used to control line vibration. If the unit has been running without a charge the system is going to be contaminated. 

Edited August 21, 2023 by Gary Cole

[Tom Cherry]

1 hour ago, CAT Stephen said:

Bill,

 

Your A/C rooftop unit was modified by the previous owner as rooftop A/Cs have factory charged and sealed A/C systems.  The issue that you will encounter if you attempt DIY is that you can't purchase R410a refrigerant without an EPA license.  Also, truck and RV shops don't have the equipment to recharge R410a systems.  And finally, a residential A/C technician will not charge your system without a high side port to monitor the high pressure side of the system.

 

Provided that you don't have an on-board aqua hot system, I recommend that you consider the following replacement unit from RecPro (Houghton) as the cost is much lower, can be controlled from your cell phone or tablet via SwitchBot, and is much quieter:

- https://www.recpro.com/rv-air-conditioner-15k-with-heat-pump/

 

Keep in mind that the RecPro unit above does not use your existing Dometic control or the Dometic thermostat.  It has its own built in thermostat and is controlled with an included infrared remote control.  Also, you can purchase a SwitchBot hub from Amazon to remotely control the unit via your cell phone or tablet.

Agreed on your dilemma.  But, be sure to read all the posts here.  The RecPro system is being used by many.  Others more successful and some not pleased.  You will have to remove the control board and the interconnecting wiring and keep your 5 button Dometic thermostat system intact if you want to control your furnace/ aquahot.  That is my current understanding that RecPro has not designed or provides a multifunction thermostat.  Your existing system will be running on a 5 button thermostat and a control module that is closing in on 20 years for heat. The 5Button Thermostat is no longer being made and the supply of ones to be rebuilt is dwindling.  Last quoted cost for a refurbished 5 button was approaching $175.  The MicroAir digital & BT thermostat has been an option.  However, it is just a “reverse engineered” system with more options for control.  One you commit  to keeping the original Dometic control system in place (you have to mount the controller in the plenum and rewire the old HVAC and Furnace lines) then, you must also replace the OLD Dometic CC control module at some future date.  They are more robust than the 5 button, but we are seeing more control module failures….just based on age and use.

Also bear in mind, that the same logic applies to the rear as well.  So, $350 for a MicroAir and possibly $175 for a new controller, as it will, eventually, die.  Then another $175 for a rear one.  A LOT of us have made the decision….when ONE AC dies….upgrade to the new CC2 Dometic thermostat and two new units.  YES, you can dumb down a new Penguin, at a cost of $175, per, to keep them running on the old, obsolete CC 5 button system.  Takes a good hour or two by a knowledgeable tech, but we have many competent here.  Then, you save the new controller….when the next one breaks, folks usually then convert back to the new technology CC2, another hour or so to get it “like it came”.  So, you spent at least $400 in labor and $175, minimum, to get another year out of the old 5 button.

BTW…Dometic does NOT provide tech support if you have a MicroAir thermostat….and MicroAir provides no tech support on “why it ain’t working”.  Folks including myself, recently helped a member diagnose what was wrong…it was his OLD control module.  MicroAir was or did send him  new Thermostat….but said, if that don’t fix it….we can’t help.  

It is a matter of fully understanding your options and also the full cost and what you want to accomplish.  Some folks are hooked on the BT MicroAir and that works for them.  MicroAir also sells a reverse engineered CC2 unit…same caveat.  You HAVE to have a working Dometic CC2 control system.

BTW….some folks abandon the heat…don’t need it or end up running wires up a wall in a piece of wire mold and installing a Honeywell line thermostat….they run $75.

Thats the skinny….just make sure you have a plan for a total system replacement and know the options and the coats of each alternative.

 

[Ivan K]

Bill, I am one of those who prefer to repair rather than replace unless I see the benefit of new features. I have fixed leaks and recharged two of my roof units for near nothing. Of course it helps that I have the tools, ASE refrigerant license and time to spend on the roof. Make sure what refrigerant is actually used in your unit and how much (should be on a sticker), mine use R22. Since you already have a port and if you decide to attempt fixing it, you can switch to heat pump mode and if they brazed the port strategically,  the port becomes your high side. Of course, you need to find and fix the leak. Oh, and that piece of rubber is vibration damper,  nothing to worry about. Or, pull your credit card as most would do...

[Bill R]

4 hours ago, CAT Stephen said:

The issue that you will encounter if you attempt DIY is that you can't purchase R410a refrigerant without an EPA license. 

Stephen - thank you for the input.  I fortunately have a friend who is a residential AC guy who charges R410A systems all the time and will do this for me.

3 hours ago, Gary Cole said:

Not sure what that is. Might be a weight or rubber material used to control line vibration. If the unit has been running without a charge the system is going to be contaminated. 

Gary - @Ivan K confirmed it is a vibration damper.  Learn something everyday.  The loss of cooling just happened so hopefully it is not contaminated.  Even so, if I end up having to replace, won't hurt to try, heh?

2 hours ago, Tom Cherry said:

It is a matter of fully understanding your options and also the full cost and what you want to accomplish.  Some folks are hooked on the BT MicroAir and that works for them.  MicroAir also sells a reverse engineered CC2 unit…same caveat.  You HAVE to have a working Dometic CC2 control system.

Tom - so well put.  I do have the MicroAir and I love it.  So if I do end up replacing the unit it would be with another Penguin II and keeping the old board just in case.

16 minutes ago, Ivan K said:

Bill, I am one of those who prefer to repair rather than replace unless I see the benefit of new features. I have fixed leaks and recharged two of my roof units for near nothing.

Ivan - this will be my initial approach.  The existing unit is quiet, has pumped cold air for the past 2 years since I purchased the coach, and very clean.  So I am hoping with the assistance of my AC friend I can just recharge and hope it lasts another 3+ years.  We will first attempt to find any leaks.  Even though they are closed systems, in my opinion that is just an OEM way of getting these things to turnover in their sales numbers.   No technical reason why they can not be treated like your car or house AC units if you have the knowledge and equipment to recharge.

 

[dennis.mcdonaugh]

My a/c units both had saddle charging ports installed when I bought the coach. Both units slowly lost coolant until I had to replace them. They had charging ports installed for a reason, they leaked!  A lot of owners have spent money, some a lot of money, to repair these units and had to replace them anyway. 

[Ivan K]

30 minutes ago, dennis.mcdonaugh said:

My a/c units both had saddle charging ports installed when I bought the coach. Both units slowly lost coolant until I had to replace them. They had charging ports installed for a reason, they leaked!  A lot of owners have spent money, some a lot of money, to repair these units and had to replace them anyway. 

Saddle ports are not a fix I would consider as anything close to permanent, they WILL leak. I used them just to quickly see if there is any pressure, find the leak and then braze a real port in their place. They could even be just soldered in just like one would do with copper plumbing, if not right at the compressor. But I don't have to pay anyone to do it for me.

[Chuckster59]

What causes the need for a Freon recharge? Is it leaks only or does it need to be done every ‘X’ years because it gets to end of life?

[Ivan K]

7 minutes ago, Chuckster59 said:

What causes the need for a Freon recharge? Is it leaks only or does it need to be done every ‘X’ years because it gets to end of life?

Leaks only.

[dennis.mcdonaugh]

37 minutes ago, Ivan K said:

Saddle ports are not a fix I would consider as anything close to permanent, they WILL leak. I used them just to quickly see if there is any pressure, find the leak and then braze a real port in their place. They could even be just soldered in just like one would do with copper plumbing, if not right at the compressor. But I don't have to pay anyone to do it for me.

They were soldered in place. You could tell they were a modification to add a charging port and not part of the original installation. Good luck with your repair.

[Tom Cherry]

16 minutes ago, dennis.mcdonaugh said:

They were soldered in place. You could tell they were a modification to add a charging port and not part of the original installation. Good luck with your repair.

Some really experienced folks have added ports and done it themselves and got some extra time….but, based on my mental scorecard, it is like a major league hitter…at best 30%….  Paying a tech or a buddy to do it is probably futile.  When one AC dies….then a need for a carefully thought out plan for the entire system is needed….unless you decide to sell it and subtract $2,500 as the “needs new front AC” deduct…

Since there are now options for a cheaper, but will not control furnace/Aquahot and fancier thermostats….the decision tree is a bit more complex.  Also knowing the limitations of the RecPro and the requirements as well as maintaining a “Dometic” MPX system in order for the aftermarket non Dometic thermostats to work as well as deciding on what level of technology, obsolete with limited parts or the CC2 system….which MicroAir does have a model for…but the old 5 button CC system will not support a new CC2….or vice versa…

Write it down….look at options.  Coat it out…but be aware of the requirements and the limitations and fully understand how it has to work as well as what features you need….

good luck…

[Bill R]

Thank you for the continued comments.  It really helps me think through everything.  I totally agree on brazing on a port, and fortunately their is one already there.  I know that means there was a leak prior, but if that leak is small enough to get 3-4 years before another recharge, I would be happy with that.

Tomorrow I am meeting with my AC Tech friend to recharge and will report results back.  This is a great forum that helps me evaluate repair vs replace.  I tend to go for repair, especially for higher cost items.  For low cost items I tend to go with replace.  Case in point, my step motor gears recently started slipping.  I could have replaced the gears, but time, effort, and a new motor for around $40, I just put a new one in.  Replace will win out if other factors come in like upgrading for cost or tech benefits or obsolescence of technology as @Tom Cherry points out.

At my house I have an AC Compressor that is around 20 years old.  It is a 14 Seer and slowly leaks R22 to where I have it recharged every 3-4 years.  With the cost of R22 going up, I was seriously thinking of just getting a new one.  But they have come out with MO 99 Freon that is much less expensive as a replacement to the R22.  So until the compressor finally dies, it is still very efficient, cools extremely well, I keep it clean and serviced, I'll continue to pay $100 every 3-4 years before paying $4,000 for a new one unless I absolutely have to.  

So, hopefully that will be the case as well for the Penguin II!  Will report back soon after we recharge. 

[Bill R]

Update: Penguin II Front Roof Top 13.5K AC/Heat Pump has been charged with 410A Freon.  56F air blowing out with 80F intake.  Been running for two days, Success!!  

When the AC tech initially went to charge the unit thinking there was a very slow leak and that is why it lost Freon, it became immediately obvious there was a bigger leak.  You could hear it.  The leak was on the switching valve assembly where the high pressure capillary tube connects to the high pressure line coming from the switching valve.  See Pic 1 below.  I was surprised at this as the PO mentioned this unit was fairly new when I bought the coach in 2021.  I called the PO to inquire.  PO informed me that the unit was a 2019 and he got it off another coach that had been in a wreck.  This all started to make sense to me.   Why did this fairly new unit have a charging valve already installed.  My guess is the unit had to be repaired and recharged after the wreck.  It was evident a leak was repaired on the same exact capillary tube except on the other end where it attaches to the switching valve.  See Pic 2 and you can see this repair.  I think there was either a very small crack undetected or a weak spot in the location of Pic 1 where this last leak occurred.  

Fast forward, I bought a new switching valve, and had the AC tech install.  Pic 3.

Here's the kicker, not knowing if I was going to be able to repair this unit, I went ahead and ordered a brand new Dometic Blizzard NXT 15K AC/Heat pump.  Specs show it blows more air than the Penguin II and reviews say it is more quiet.  Sits only 2.5" higher than the Penguin II.  I took advantage of the Wal-Mart sale and for $1,100 including tax had it shipped for free to my home. 

My plan is to in the upcoming months replace the existing front Penguin II unit with this newer NXT and keep the Penguin II as a back up for the rear AC which is a Dometic DuoTherm 13.5K AC/Heat Pump and original to the coach.  Still works like a champ except the compressor is kind of loud when it shuts down.

Glad to be feeling cool again!!

Pic 1

Pic 2

Pic 3

 

 

Edited August 31, 2023 by Bill R

[Gary Cole]

Hi Bill, glad everything worked out. Appreciate the pictures and follow up.  lOnly thing I'm wondering about is that your 4  way valve is firmly lashed to the compressor housing without  rubber isolation. Lots of unnecessary vibration/stress being transmitted from the compressor housing to the system piping.  That can result in premature  joint failures.  If you loosen the clamp where does the valve/tubing want to be?  Gentle restraint, damping, and tubing radius to provide flexibility is the preferred method. 

 

Edited September 1, 2023 by Gary Cole

[Bill R]

18 hours ago, Gary Cole said:

lOnly thing I'm wondering about is that your 4  way valve is firmly lashed to the compressor housing without  rubber isolation.

Gary - Thank you for pointing this out. if you look in Pic 3 at the top of the reversing valve there is a thick rubber washer I added to dampen vibration.   When I first saw this configuration on the old reversing valve in Pic 1 I wondered why this was done.  Then I noticed that on my rear AC DuoTherm it has the same setup with the band clamp but no dampening material.  Also on the new NTX it has the same set up.  So this is OEM.  I guess for some reason beyond my ability to explain.  But I still went ahead and added the rubber washer.  
 

 

Edited September 1, 2023 by Bill R