Replacement advice for Coleman Mach AC

[BauerAP]

2019 Sprinter 32FWBH purchased April ‘19

Last weekend our main AC froze while in the middle of our trip. Luckily we made it through with moderate temps and running the fan to circulate the front br AC.

Now comes what’s next. I’ve cleaned the coils and checked for any airflow blockages. Looking through paperwork I can’t find anything about the extended warranty info. (Yes, I know, that’s a different topic and it’s already been purchased so we don’t have to go there)
I will be contacting Camping World when I get the opportunity. Manufacturers warranty is two years, so we’re past that.

In the minimal searching I’ve done I’m not sure if I have a 13.5 or a 15k. Either way, now is the time to go bigger if I’m coming out of pocket.

Should I switch to a different unit? The Furrion chill 15.5 is a couple hundred dollars less about will have to buy the $100 harness. Any other tips/hints/suggestions you guys might have?

[chuckster57]

I just got training on the Furrion A/C and from what the instructor said (former Dometic AC tech for 10+ yrs) they are stout units. Lots of newer technology including two seperate motors for less amp draw. If/when mine fails I’m switching.

[rhagfo]

Your AC froze up once and you are going to replace it?
There are lots of reasons an AC to freeze up (iced up).
First close the “quick chill” vent on the bottom of the unit, so cold air doesn’t get drawn back in the intake. Seal the intake side so it only draws through the intake.
Watch your interior humidly, if I a high humidity area get a dehumidifier.

[wiredgeorge]

If you have your temp set fairly high and fan speed on low, the unit will freeze up; especially in more humid conditions regardless of make/model. If you look into the A/C from beneath and see a chunk of ice, that could well be the cause. Freeze ups have happened to many of us.

[BauerAP]

Replacement is definitely not my first choice. It seems my only option after looking into it.
After doing the inspection/cleaning what else is there to do? There is no service port on the sealed unit so it can’t be recharged. It shows symptoms of low refrigerant.
I have the “mod” done that eliminates the quick dump and maximizes flow. My initial thought was the tape came off of one of the panels and was blocking airflow.
The unit has been dried and then tested 4-5 times and has frozen in 1-2 hours in different temps and humidities.
Initially the air flow is great and the air is cool and then the flow drops and it becomes a fan.

[BauerAP]

Just and FYI temps have ranged from 60-90 and humidity has been from mild to moderate. No, I do t have percentages but I’m in central NC and it’s May.

I’m also one to abuse the paid for electricity and the temp will stay set at 68 or less until DW makes me change it.

[flybouy]

Originally Posted by BauerAP

Just and FYI temps have ranged from 60-90 and humidity has been from mild to moderate. No, I do t have percentages but I’m in central NC and it’s May.

I’m also one to abuse the paid for electricity and the temp will stay set at 68 or less until DW makes me change it.

Here's where I'd start: if you don't have an IR thermometer go buy one, they are inexpensive and very useful. Start A/C and check inside air temp at the return air grill and the discharge temp at the unit. Remove the cover if you don't have the dump valve. The differential should be about 17° - 20°. Check the placement of the freeze stat on the coil. It's not uncommon for them to get knocked out of place.

Have you cleaned the condenser coil? It's only accessible from the inside. I use a "no rinse" coil cleaner on mine. Spray it down, wait 15 min. then turn on the A/C unit. The condensate will wash it off. Speaking of condensate, does it drain from the unit (i.e. roof) well? Run the unit with the fan on high and manual so it runs continuously.

If you like wasting electricity and keep the door open then the A/C will never keep up and in high humidity environments will freeze up the coils. So will using an airconditioner to do the work of a walk in refridgerator.

Not being critical but if your issue is operator error then spending money won't solve the issue.

:

[BauerAP]

Originally Posted by flybouy

Here's where I'd start: if you don't have an IR thermometer go buy one, they are inexpensive and very useful. Start A/C and check inside air temp at the return air grill and the discharge temp at the unit. Remove the cover if you don't have the dump valve. The differential should be about 17° - 20°. Check the placement of the freeze stat on the coil. It's not uncommon for them to get knocked out of place.

Have you cleaned the condenser coil? It's only accessible from the inside. I use a "no rinse" coil cleaner on mine. Spray it down, wait 15 min. then turn on the A/C unit. The condensate will wash it off. Speaking of condensate, does it drain from the unit (i.e. roof) well? Run the unit with the fan on high and manual so it runs continuously.

If you like wasting electricity and keep the door open then the A/C will never keep up and in high humidity environments will freeze up the coils. So will using an airconditioner to do the work of a walk in refridgerator.

Not being critical but if your issue is operator error then spending money won't solve the issue.

:

I didn’t mean to say that I was wasting electricity, I just keep the camper thermostat cooler than I typically do at home. Which was in response to another comment about the thermostat being set high.

With a 7 and 3 year old the door does get left open longer than I’d like at times and I’m the first one to get them or get it closed. This wasn’t the issue since it was frozen after 6-8 hours of pool/beach time. And when testing it has been open and close and not left open for any extended time. I’m not one to leave the screen door closed with the door open.

I will snag a thermometer as soon as I can. Wish I would have yesterday with the 25% harbor freight coupon.

I have not cleaned the coil inside. It was draining fine until it froze the condenser and was dripping in the kitchen.

[JRTJH]

I think what everyone is saying is that if the A/C froze up one time and you're talking about changing it out, we all feel you're jumping the gun....

An RV air conditioner will freeze up if the fan speed is on low and the humidity is relatively high. The condensation will cause that to happen. There is a "freeze detector plug" inserted into the coils in the air conditioner. If it is inserted into the coils too high, the unit will freeze. If it's not plugged in properly (vibration from towing) the unit will freeze. If the thermostat is set too low, the unit will freeze. NONE of those indicate a defective unit or a need for replacement. They all are "easily fixed issues or improper use"....

[notanlines]

Is this the same Furrion name brand that is associated with RV electronics? Might want to look hard at giving up Coleman or Dometic.
A little click bait to read through: https://www.forbes.com/wheels/access...-conditioners/

[chuckster57]

Originally Posted by notanlines

Is this the same Furrion name brand that is associated with RV electronics? Might want to look hard at giving up Coleman or Dometic.
A little click bait to read through: https://www.forbes.com/wheels/access...-conditioners/

If my sources are correct, Lippert (owns Furrion) bought Dometic.

[ChuckS]

I would have to check the placement of the freeze sensor on the EVAP coils… if you can find the service manual with troubleshooting info for this unit it might also help

[BauerAP]

So, finally got a chance to dig a little deeper. Freeze sensor was in place and plugged in properly. I took it out and put it on an ohm meter. Started at 9.8 and dropped as I held the sensor. So unfortunately, it looks like it is working.

I did order another sensor last night as well as a no rinse coil cleaner. They do look like they could afford to be cleaned. If sensor replacement and cleaning doesn’t work, are there any more boxes to check?

[JRTJH]

Originally Posted by BauerAP

So, finally got a chance to dig a little deeper. Freeze sensor was in place and plugged in properly. I took it out and put it on an ohm meter. Started at 9.8 and dropped as I held the sensor. So unfortunately, it looks like it is working.

I did order another sensor last night as well as a no rinse coil cleaner. They do look like they could afford to be cleaned. If sensor replacement and cleaning doesn’t work, are there any more boxes to check?

Just remember that a properly working air conditioner, when operated in high humidity on low fan speed in some temperature ranges WILL (not might) cause the coils to freeze. There is not enough velocity across the coils to pull the condensation out of the spaces and as it freezes, it will build on itself until airflow stops. Somewhere, long ago, in a land built on common sense, not on "my comfort at any cost", the Dometic owner's manual used to have a note in a black box warning of that problem. I suppose over the years, they stopped printing that note, likely to save ink since nobody reads the owner's manuals any more and even if they do, they skip over parts that don't look important.....

My Ford owner's manual devotes over 300 of the 500 pages to how to tune the radio/sync a phone with the center "touch operation screen" and only devotes 2 pages to not burning up the transmission while towing....

The point, after my rant, is that there may be nothing wrong with your air conditioner, if you're operating it outside its parameters, what happened may well be "normal expectations and fully expected results".....

[BauerAP]

Thanks John.

I will finally have time this week to dive into it. I’m just wondering why it did it this time. We’ve been in hotter and more humid situations with it the past 3 years and haven’t had the first issue. I’m not trying to argue at all. It was set at 72 high auto. Temps were in the low 80s with mild humidity. We’ve been in direct sun in the mid 90s with high humidity multiple times with no issue.

The fan has never operated on low. So that operator isn’t a possibility. I should have had it looked at under warranty but never did due to losing camping season and forgot about it in the off season.

I don’t have any desire to replace the unit. I just want it to operate like it has the past couple seasons.

[JRTJH]

If I understand correctly, it froze up one time and you're concerned that it might do it again and you're considering buying another $1000 air conditioner because it "MIGHT" do it again ????

If that's the situation, I'd really, REALLY suggest that you try it and see if you have the same kind of problelm... It might happen the first time. On the other hand, you might go the entire camping season with no problems at all.

Look at it like having a box of strawberries in the refrigerator. They've been there a week, so without checking or confirming, you just throw them away and go to the store to buy another box. There's no assurance that the ones on the store shelf won't be a week older than the ones you threw away and what you end up with is 2 or 3 week old strawberries rather than 1 week old dessert.....

And, to top it all off, it may not be a problem with the air conditioner, but a problelm with the installation and/or with the ducting in the ceiling that's restricting airflow. Installing another unit may give you the same results that you currently have, but with a significantly lighter wallet.

If you look at it this way, maybe it'll make sense to try it and see if the problem repeats or if you go months/years without any repeat issues....

[BauerAP]

Please refer to my second post in the thread. I didn’t go into as much detail.

It froze Friday morning, I let it thaw/dry until that night about 14 hours. It was refrozen by the morning Saturday. I only ran the fan on high during the thaw. I turned it on Sunday morning after a 24 hour thaw/dry and it was frozen by the time we packed up and got ready to hook up.
I turned it back on one day during the week 2-3 days later and had frozen again when I went to check a couple hours later. All with different temps and humidities. None out of our ordinary camping temperatures. This was all before I did any real investigation as I only had anything tall enough to pull the cover and plenum off.

I didn’t just jump off the deep end with the plan of throwing $1000+ into the fire.

[JRTJH]

Somehow I missed that post... I'd be concerned with multiple issues too....

Have you removed the ceiling unit and inspected the duct separator panel and the ducting connections to the unit? It may be "blowing chilled air into the return warm air section if that duct separator is not installed correctly or if it missing (yes, seen that happen more than once)....

I'd just hope that buying a replacement, installing it and finding out that you have exactly the same problem doesn't happen...

Freezups happen for three main reasons, Cold air circulating back into the warm air intake, duct restrictions that interfere with air movement through the evaporator and low/leaking freon. The first two are not a "rooftop unit issue" and replacing it won't fix the problem (money wasted)... If you have an "amp clamp" you can measure the compressor draw and use the chart in the owner's manual/service manual to determine the freon charge status.

[BauerAP]

Just an update. After moving the freeze sensor up about halfway up the coils we made it through a holiday trip with airflow across half of them.

Today was the first available appointment at CW and dropped it off this morning. After a little bit of a headache but nothing major I was satisfied the issue would be resolved. CW is approximately 40 miles from home so not terrible.

Got home and halfway through the yard I received a phone call saying I had a new unit and everything went as planned. Compressor went out is what they told me.

I was ready to come home plug it in and give it a whirl. Well I did and everything is fine and cooling as it should. I will do the bypass mod again asap. I didn’t realize what a difference it made until I went back to stock.

So everything is good and well until I pull the covers off and am now wondering if I got a used unit. The amount of dust in the filters and filter covers seems excessive for maybe, and it’s a stretch, 2 hours of operation.

Going to try to post a few pictures. What do you think?

[JRTJH]

Typically, they don't change out the "entire unit", if the "top unit fails" they change what's on the roof and reuse what's inside the trailer on the ceiling. Same with replacing the ceiling components, they don't change out the rooftop part...

What you're seeing is probably your old "inside components" with a new rooftop unit. That would explain the "more dust than expected for 2 hours of operation"... If they removed your ceiling panel, laid it on the floor, it was cooler than the carpet and condensation collected, then the dust/dirt would stick to the wet panel... And we all "know instinctively" that RV techs don't clean up well after themselves, they have the "cleaning lady to do that for them" (except this time)