Proactive AC Replacement?

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Proactive AC Replacement?

May 06, 2019, 11:52:26 am

Our coach has original roof AC heat pump. 165k miles. I do some preventative maintenance, like replaced the alternator last winter. Maybe replaced a perfectly good one, but it had been many miles.

In that vein, I am thinking to replace one, probably front, AC just to better assure we not lose both ACs on a trip.....I assume it unlikely would lose both of the originals at once, but you know what they say about assumptions. Thus one new good one is insurance?

SO....thinking to replace one with a new if I can get a good price. Good idea or not?

And if do, was thinking.... stay with the original design butI have heard some pros, and oons, of alternative models. I will search the Forum on that but welcome of course your input on models.

Thanks....

Thanks for opinions.....

Re: Proactive AC Replacement?

Reply #1 – May 06, 2019, 12:13:36 pm

I don't know, the OEM AC's are still working just fine on my 99. Where it me I would leave them alone and service them annually and call it good.

Re: Proactive AC Replacement?

Reply #2 – May 06, 2019, 12:29:20 pm

I agree with Bruce.

Re: Proactive AC Replacement?

Reply #3 – May 06, 2019, 12:39:00 pm

Following Bruce, our coach built in 1996, original roof airs work just fine. We have cleaned evaporator coil, but it worked fine before cleaning, too.

But then, we do like proactive maintenance and improvements

Re: Proactive AC Replacement?

Reply #4 – May 06, 2019, 12:42:07 pm

Our original units were working fine in 2013, and we took off on a summer trip to Colorado and lost the front unit in New Mexico. That turned into a nightmare. We went on to Colorado, but stopped on the way back in Albuquerque and had both units replaced. It caused us a bunch of inconvenience and loss of time on our trip, and the units were not wired correctly which we didn't figure out until they quit at the bottom of Palo Duro Canyon.

Just depends on your tolerance for inconvenience, I suppose! Mine is low.

Chris

Re: Proactive AC Replacement?

Reply #5 – May 06, 2019, 12:46:38 pm

Still on our origins 02's.. still running strong until some self inflicted wounds but it will be fixed with the new board

Re: Proactive AC Replacement?

Reply #6 – May 06, 2019, 01:42:53 pm

Original 93's going strong here. I do annual maintenance/filters, etc.

Re: Proactive AC Replacement?

Reply #7 – May 06, 2019, 02:55:45 pm

Still using our originals from 2001-

" If it ain't broke, don't fix it"

Just do maintenance.

Re: Proactive AC Replacement?

Reply #8 – May 06, 2019, 03:28:58 pm

Have to side with Chris on this one. I, too, believe it is better to replace something on my schedule, at a location of my choosing...even if it ain't broke. That's why our coach has a new inverter/charger, new coach and chassis batteries, new lift pump, new fuel shutoff solenoid, new isolator, new ignition and boost solenoids, new tires, etc. All that stuff was still "working" when replaced.

Our OEM A/C units are both still working, but for how long? One of them has already (twice) doused our bed with water after the styrofoam drain pan suffered from (age related) deterioration. The evaporator fins on both units are starting to break and fall off. They are so fragile that barely touching them is impossible, much less cleaning them with a stream of water. There is a sticker on the rear unit showing it was actually manufactured in 1991, making it 28 years old. Surely, by any standard, it is near its "end of life".

We are planning several trips this summer, to places where it will be HOT and HUMID. My DW has flatly stated that one (or both) A/C units failing while on the road will NOT be acceptable. Both for my own peace of mind, and in the interest of "happy life", I have initiated the process whereby our OEM roof A/C units will be replaced by 2 new Atwood 15,000 BTU heat pumps. Units are ordered, and appointment is made for installation (Nacogdoches Motorhome Service).

If anyone wants my old Penguin units (for spares) they are yours for free (you pick up). Otherwise I'll give them to NMS to do with whatever.

Preventative replacement may not suit everyone, but it works for me. DWMYH

Re: Proactive AC Replacement?

Reply #9 – May 06, 2019, 03:42:33 pm

What is to say your new unit dies before your existing units?

Read these other forums where they have a lot of members with brand RV's. I am amazed how many units are getting replace under warranty, and this is only the ones that are posting about their AC problems or on the forums.

I have a friend that had a 2016 Coach. He went thru 4 or 5 AC units in I think the first year. One time he had all 3 units dead.

Based on all that I have read I would roll my dice on sticking with my old working units.

Re: Proactive AC Replacement?

Reply #10 – May 06, 2019, 04:54:44 pm

The units on my '81 are still working and my son has been living in it since 2015. If one breaks down on one of my trips I am sure I can live with it until I get back home where my crane will make the job easy.

Re: Proactive AC Replacement?

Reply #11 – May 06, 2019, 05:11:29 pm

I tried to tell my wife and 2 young children we would just "live with it", but New Mexico and all of west and southeast Texas said otherwise. Rough.

Re: Proactive AC Replacement?

Reply #12 – May 06, 2019, 05:13:34 pm

I have gotten to where I like to avoid when I can just living with something. Plus I was raised with a preventative
maintenance mindset I guess.

My lesson experience that got my attention on the AC was.....we lost both ACs one summer going east from Amarillo and in Dallas where by late afternoon the temp was ambient 103. That is not fun

Then a friend of mine with a coach a bit older than ourslost his just as going to head out of town. Got my attention, there seemed to be no warning to him

I have measured temps. Given an inside coach temp of 80 degrees to start, the rear AC gets air to a low temp of 47 degrees just after the fan and the front AC gets down to 52 degrees. The inside surface temperature gets to 30 degrees and 38 degrees respectively. That seems to me.....no expertise in such....that they are performing well though I do not know what I do not know.

My dash air is doing well best I can tell, 54 degrees air.

Thanks

Re: Proactive AC Replacement?

Reply #13 – May 06, 2019, 05:17:05 pm

Mike, from what I remember you have some spare space in your basement. Get a new one now with all of the things that you will need when it comes time to replace it and haul it around for another five years and then you will have one when it is time to replace one or the other of them. Or do them both now 🔜 and be happy.

We have heard some incredibly noisy AC units on newer coaches, especially Phaetons. Real howlers. They might be quiet inside but you neighbors will hate you. Go for quiet inside and out.

We use ours much less than you do down in TX so I am sticking with what I have until the time comes. We use the BR AC much more than the LR AC, Maybe just swap them front to rear. Makes some sense.

This same idea lends itself to your AH. Our LR circulator pump runs 50x as much as the Bathroom and Bedroom zones. Swap two hoses and a couple wires and you just changed which pump does which zone.

Re: Proactive AC Replacement?

Reply #14 – May 06, 2019, 07:26:19 pm

With space in the basement how about a quiet residential unit ducted somehow?

Re: Proactive AC Replacement?

Reply #15 – May 06, 2019, 10:13:40 pm

Quote from: Michael & Jackie – May 06, 2019, 05:13:34 pm

I have gotten to where I like to avoid when I can just living with something. Plus I was raised with a preventative
maintenance mindset I guess.

My lesson experience that got my attention on the AC was.....we lost both ACs one summer going east from Amarillo and in Dallas where by late afternoon the temp was ambient 103. That is not fun

Then a friend of mine with a coach a bit older than ourslost his just as going to head out of town. Got my attention, there seemed to be no warning to him

I have measured temps. Given an inside coach temp of 80 degrees to start, the rear AC gets air to a low temp of 47 degrees just after the fan and the front AC gets down to 52 degrees. The inside surface temperature gets to 30 degrees and 38 degrees respectively. That seems to me.....no expertise in such....that they are performing well though I do not know what I do not know.

My dash air is doing well best I can tell, 54 degrees air.

Thanks

My 89s were working working fine until I plugged into a yard light post outlet in my driveway. Lost one due to low voltage and polarity issue for that outlet. Something wrong with 47 or lower degree readings on HVAC units

Re: Proactive AC Replacement?

Reply #16 – May 07, 2019, 06:12:07 am

My 21 year old units started leaking, creating stains on the headliner. Do it.

Re: Proactive AC Replacement?

Reply #17 – May 07, 2019, 08:11:18 am

Replacing just one may give you compatibility problems between the control boards and with the thermostat. Replaced both of ours, and the thermostat. We were planning an extended trip in Mexico, no wish to deal with ac failure while there.

Re: Proactive AC Replacement?

Reply #18 – May 07, 2019, 09:30:43 am

Phred, what is wrong with 47 degrees? You telling me that is too low and too low indicates a problem?

If it matters, I used a thermometer and placed it up inside the duct right near the fan, this is not a measurement at the outlet grate.....it is about 52/54 there

Thanks

Re: Proactive AC Replacement?

Reply #19 – May 07, 2019, 12:03:28 pm

This will also give you the chance to replace the gaskets. Mine were obviously leaking in the past and had HUGE amounts of caulking gooped all over these 14x14 inch gaskets, rendering them ineffective and prone to leakage. So, while you are replacing the gasket, why not just replace the whole unit? At today's labor rates, you might as well get another 20 years of worry-free operation instead of wondering when the next leak will occur.

That said, I recommend everyone to torque the gasket bolts to the recommended value periodically. My old bolts were loose. When I torqued the new unit's bolts, it seemed there was too much pressure on the AC unit and roof, but I got as close to the torque value as I dared.

Re: Proactive AC Replacement?

Reply #20 – May 07, 2019, 12:47:08 pm

Mike,
Can't stay quiet any longer:
Lots of questionable advice from lots of people that don't know what they don't know.

First of all, your proposal to use blind Preventative Maintenance can be a waste of money, but in this case, it can get you into serious trouble, especially if you follow much of the advice given to you thus far.

It is much better to use a philosophy of Predictive Maintenance rather than BLIND Preventative Maintenance or Corrective Maintenance (Fix it when it breaks) philosophy.

What's the difference between Preventative and Predictive Maintenance?

Use engine oil and filter changes as an example:

Corrective Maintenance: Change oil and filters when the engine quits - obvious poor choice.
Preventative Maintenance: Adhere to OEM recommendations - OK but these are usually based upon harsh or conservatively more damaging than "average conditions". That may well be woefully ignorant of the actual conditions under which you have used the engine.
Predictive Maintenance: Put technology to use and conduct periodic fluids analysis. Use good record keeping practices (including engine severity of use conditions) to understand how your fluids and engine are actually doing. This may shorten, but will most likely significantly lengthen, your conservative maintenance intervals and therefore costs.

OK, what are the VITAL indicators of a healthy Rooftop AC in an RV, that are needed for a valid Predictive Maintenance attention and service approach?

Pretty simple answer really:

Is it cooling? (18 to 20 degrees F delta (**See Below) from inlet to exhaust of evaporator - use a direct reading thermometer, right at the AC inlet and outlet vents). If the hermetically sealed compressor has failed, then it's time for an AC replacement.

Has operating noise level changed? (use either a professional sound measurement meter or something like one of the MANY FREE smartphone apps that have good NBS (National Bureau of Standards) ratings, and record your readings, over the years). I use the National Institute for Occupational Safety and Health smartphone App. NIOSH. My AC's run 56.1 to 56.8 dBA*

What are the current draws (fan and hermetically sealed compressor unit) off of the AC breaker? (for my (three) OEM 1/4 HP Dometic DuoTherm Penguins, those values are 3.5 to 4.0 DC amps running, 5.5 to 6.5 DC amps starting for the fan and a total of 15 to 19.5 DC amps running for the fan plus compressor, depending upon where the compressor is in its charge cycle. Of course, one has to invest in a good multimeter that can sense and accurately capture starting and running amps).

Are the Start and Run capacitor values within spec? Each cap has spec's., generally clearly imprinted right on the cap. The capacitors are the most likely components to not stand the long term test of time. On the other end of the spectrum, the hermetically sealed compressors can run for thirty years continuous, without issue.

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Obviously you have to do these Predictive Maintenance checks at some reasonable interval and that depends upon your conditions of use:

My wife has debilitating asthma and allergy respiratory conditions. In big picture terms, our home is on long term lease, our coach is 17 years old and we full time, in high heat load, hot weather areas. For the most part, we follow the good weather, keep windows shut and run one or two of the three AC's 24/7/365. Our #2 AC gets the most use and I replaced the fan motor on it during this past year because its running amps were becoming too high. It actually overheated and slowed to a stop on one occasion, which kicked me in the butt and lead to the changeout (not the easiest thing to do because the airflow plenum had to be de-and-then-reconstructed).

Also obvious is that you have to maintain clean filters and AC heat exchanger coils. You have to do that on a schedule befitting your use and environment. I do my filter cleaning each four months (no pets and minimal dust) and my other checks once per year.

You must be aware that you can't use just anything to clean those coils inside the rooftop shroud and plenum. Bare aluminum placed on a stump in the woods will last centuries. AC aluminum coils sprayed with corrosive chemicals and not properly rinsed/inerted, will crumble much sooner. It is crucial that you use proper cleaning (I use Lowes commercial AC products) and rinsing (demin water) fluids.

So, why change out the fan motor in a 17 year old AC?

Here's where you need to really pay attention:

I had noticed, as TURBOJACK has mentioned, that many of the newer coaches were changing AC's unreasonably soon. I knew that my Predictive Maintenance data was still solid, the routine maintenance and cleaning observation of component internals and externals was good to excellent (excellent material condition, appearing almost new), so what was the problem in the new coaches after such short periods of time? Everyone was complaining about noise.

I went to two local RV Sales and Service Centers, one being the largest Tiffen, Newmar, Airstream, Thor, Renegade, Winnebago, Dynamax Dealership in the Southeast (North Trail RV), and I went to our own mobile service reps. here at RiverBend. What I learned was that a few years ago (different for each manufacturer), production shifted to southeast Asia. Dometic, Coleman, Advent, and now Atwood (under Dometic control) all keyed on the Southeast Asian paradigm shift to "Planned Obsolescence" i.e.- build it cheaply, pump it out inexpensively, replace a small fraction when there is a successful warranty, claim, but generate as much cash flow as possible on sales and service.

At RiverBend alone, out of the 47 AC replacements done by one on-site Mobile RV Service, 4 were "old", USA made Dometic and Coleman units. The other 43 replacements (mostly Tiffen, Newmar, Prevost and Newell) were all less than 5 years old, all were either Chinese or Korean manufacture and some were lasting less than a year. Those were on coaches with dark paint and poor insulation characteristics (one Prevost in particular had replaced all four units two times in less than 28 months). Several Newells, Tiffens and Newmars had less than two year longevities on new Dometics, Colemans and now Atwoods were beginning to show up.

So all of this obsession with noise* and the "before and after", stated in purely emotional, unqualified terms may be meaningful to some, but until you collect reliable sound measurements using NBS reasonable equipment, it doesn't make sense to me to change out OEM equipment, that usually has at least 10 to 15 additional years of useful lifetime, to something that will probably last only 3 to 5 years, and then only if maintained properly.

To each his own, but I see a lot of the previous discussion in this thread as nonsensical and surely not technically sound. If you don't have the technical or physical ability to implement all of what I'm recommending, you would still be dollars and "pleasant RV'ing experience" ahead by finding a surrogate to carry out the above, IMHO.

HTH, Neal

*dBa Readings:

60~67 Quiet Conversation
67~70 Normal Conversation
70~72 Public Speaking
82~92 Quiet Church Music
92~95 Typical Church Music
95~102 Loud Church Music
115~125 Rock Concert
Etc... you get the idea

**Ideal Delta T limits for cooling:

On the cooling side, the ideal Delta T range varies depending on who you ask, but a good rule of thumb is between 18F and 22F. Generally speaking, if Delta T is high, it can indicate poor airflow. If Delta T is low, it can indicate poor system performance or capacity.

Low Delta T:

Delta T below approximately 18F can indicate a number of potential issues, including:

Undercharge or low refrigerant levels

A malfunctioning metering device

Too much airflow through the evaporator

Abnormally high humidity

Liquid line restriction

A malfunctioning compressor

Leaking reverse valves

Hermetically sealed compressors can run for thirty years continuous, without issue. But if it or the coils have failed, you would be dollars ahead to replace the rooftop AC unit, rather than trying to rebuild it.

High Delta T:

Delta T above approximately 22F can indicate a couple issues, including the following:

Low air flow resulting from a dirty intake filter, evaporator or blower wheel.

Abnormally low humidity

A blower that's not running the correct speed (eg. - Fan motor bearings slowing down fan RPM)

If you're seeing a high Delta T and you're not sure where the issue is, try checking the intake air filter, humidity levels or blower motor to ensure proper airflow.

Re: Proactive AC Replacement?

Reply #21 – May 07, 2019, 02:30:48 pm

Outstanding Neal. I am a firm believer that cheap Chinese and Korean products are not the cheapest option when they quit working so soon. I have a freezer that my Dad bought me in 1978 that is still running strong. And I doubt the replacement will make 10% of that time.
My question is, who is going to make the products that we need when the USA is at war with China?

Re: Proactive AC Replacement?

Reply #22 – May 07, 2019, 02:46:24 pm

My folks had an indestructible freezer that lasted forever. We bought a new freezer that used less power in a year than the folks freezer used in a year. Power savings alone paid for the freezer in six or seven years. We got another new one 18 years ago when we moved (left the first one in the house we sold) and this one uses even less power, about $18 worth of electricity a year.

Some of what makes them cheaper is lighter duty components that are much more efficient. The improvements in efficiency alone will pay for a new refrigerator every 7-10 years.

So it is a balance between recycling old appliances that used much more resources to operate and replacing them with much more efficient ones that might not last as long and are more recyclable.

It was question about replacing an air conditioner not a non-US product bashing free for all.

Re: Proactive AC Replacement?

Reply #23 – May 07, 2019, 02:49:36 pm

Thanks Neal,

This reminds us that over the years with our roof air's, we have changed out boards with new relays when we switched to 4-button thermostat. Replaced all the condensers, oiled motor, cleaned coils with aluminum a/c coil spray foaming cleaner, removed heat strips, changed intake filter material, have dial thermometer in air flow, added temp sensor switching & modified air flow ducts. Many of these have been repeated over time.

To think all this time since we still have original roof air, figured they are still working ok without much intervention.

Re: Proactive AC Replacement?

Reply #24 – May 07, 2019, 03:35:16 pm

Quote from: John/Pat – May 07, 2019, 02:30:48 pm

My question is, who is going to make the products that we need when the USA is at war with China?

Hopefully we can once again better produce our necessities here in the USA.

I have Hotpoint refrigerator (circa 1958) in my shop that was given to me in 1974.
It has been plugged in and running every day since, with the exception of eighteen months in the early '90's while it was in storage when we built our house. I defrost it every two or three years and keep the coils clean. I think it's longevity is due to the fact that the coils are on the back and it has no auto defrost cycle. It was made in the USA.

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