Domestic ac freeze up

stew47 wrote:
Well for an update it appears the sensor is where it should be. Ran it a little yesterday and seems to put out good cold air. Now for the strange part. When I shut off on the thermostat something up there is still running. Not the fan maybe the compressor? It only shuts off when I throw the breaker.

I've got scheduled for service in couple weeks.

Sounds like the control box is shot.

Joe417 wrote:
I've seen one freeze when the divider between the supply air and the return air intake comes loose or leaking a lot of cold air into the return.

My neighbor's unit had a piece of plywood taped in with aluminium duct tape. It came loose.

That was our issue, a few strips of foil tape sealed the cross over leaks.

Well for an update it appears the sensor is where it should be. Ran it a little yesterday and seems to put out good cold air. Now for the strange part. When I shut off on the thermostat something up there is still running. Not the fan maybe the compressor? It only shuts off when I throw the breaker.

I've got scheduled for service in couple weeks.

Bad sensor?

dougrainer wrote:
1. The First Bulletin said nothing about freeze ups. Just that they had a problem with leakers on 2 percent of the units. The problem cropped up in the first year of ownership, so if you had a suspect unit after 2 to 4 years, odds are yours is OK

No, it said that they had leakers. And the first symptom of a low charge is, wait for it, freeze ups. If you've got good airflow, high ambient temp and it freezes, the 99% probability is low on gas. Once that gas leaks out it stops cooling.

There's a rash of failed Dometics being reported all over the place from 2013 to today. Coincidence? Or Dometic trying to cover their butts to avoid a recall?

2. The 2nd link is 20(TWENTY) years old. The freeze sensor shown has been discontinued years ago(about 16 years). You will note that IT is installed at the bottom of the coil. YOU stated yours was in the MIDDLE, which is where the RV maker installed it, not Dometic. Sooo, if you had freeze ups on the 1st 2nd and maybe 3rd unit, LOOK AT YOUR INCOMPETANT Service person. They should have KNOWN the sensor was NOT in the correct place. At the bottom area of the coils about 1 to 2 inches up.

And in the failure mode of the 2nd unit it would have done NOTHING as the coil never froze at the BOTTOM where your document said it should go. Therefore since the unit was low on freon and freezing at the TOP of the coil the bottom was never cold enough to freeze. And yes it did freeze up. Ice shards in the ducts sound like glass breaking and I cleaned up numerous puddles that weekend.

Our service people are quire competent. Each time they resealed the divider better than the factory. Heck the last replacement they went to bat for us with Dometic to get that unit covered under warranty even though it was a few weeks out.

3. AS I STATED, if you had freeze ups, and had the Freeze Thermister and installed in the correct place, your units could not freeze up. Maybe not cool correctly but not freeze up.

Since I had a freeze up at the TOP of the coil and a correct sensor would be at the bottom of the coil, that's a LOT of freezing before it got to the sensor. In our case it never made it to the bottom.

4. I guess people do not need knowledgeable Service people, just look it up on the Internet. There is NEVER bad info on the Internet. Or info that when read, will be taken out of context.
5. Since you think searching the Internet makes you smarter than me, look at page 6 of this link. Doug

http://bryantrv.com/docs2/docs/ccc5.pdf

I have a good working knowledge of how an AC system works. How the parts work together. Have troubleshooted car and home ACs. I have close family members that are lifelong HVAC techs. Classic symptom of low gas is freeze ups if all the others are good. It's documented in many AC texts, on the Net, etc.

Having that sensor at the bottom would have done nothing in our case until the whole coil froze up.

I get that you are having a hard time being wrong but I know what ours experienced. Perhaps a refresher on AC theory and operation?
I know and have verified the symptoms with other HVAC techs. After replacing the units the AC works perfectly so something was wrong.

dougrainer wrote:
1. The First Bulletin said nothing about freeze ups. Just that they had a problem with leakers on 2 percent of the units. The problem cropped up in the first year of ownership, so if you had a suspect unit after 2 to 4 years, odds are yours is OK

No, it said that they had leakers. And the first symptom of a low charge is, wait for it, freeze ups. If you've got good airflow, high ambient temp and it freezes, the 99% probability is low on gas. Once that gas leaks out it stops cooling.

There's a rash of failed Dometics being reported all over the place from 2013 to today. Coincidence? Or Dometic trying to cover their butts to avoid a recall?

2. The 2nd link is 20(TWENTY) years old. The freeze sensor shown has been discontinued years ago(about 16 years). You will note that IT is installed at the bottom of the coil. YOU stated yours was in the MIDDLE, which is where the RV maker installed it, not Dometic. Sooo, if you had freeze ups on the 1st 2nd and maybe 3rd unit, LOOK AT YOUR INCOMPETANT Service person. They should have KNOWN the sensor was NOT in the correct place. At the bottom area of the coils about 1 to 2 inches up.

And in the failure mode of the 2nd unit it would have done NOTHING as the coil never froze at the BOTTOM where your document said it should go. Therefore since the unit was low on freon and freezing at the TOP of the coil the bottom was never cold enough to freeze. And yes it did freeze up. Ice shards in the ducts sound like glass breaking and I cleaned up numerous puddles that weekend.

Our service people are quire competent. Each time they resealed the divider better than the factory. Heck the last replacement they went to bat for us with Dometic to get that unit covered under warranty even though it was a few weeks out.

3. AS I STATED, if you had freeze ups, and had the Freeze Thermister and installed in the correct place, your units could not freeze up. Maybe not cool correctly but not freeze up.

Since I had a freeze up at the TOP of the coil and a correct sensor would be at the bottom of the coil, that's a LOT of freezing before it got to the sensor. In our case it never made it to the bottom.

4. I guess people do not need knowledgeable Service people, just look it up on the Internet. There is NEVER bad info on the Internet. Or info that when read, will be taken out of context.
5. Since you think searching the Internet makes you smarter than me, look at page 6 of this link. Doug

http://bryantrv.com/docs2/docs/ccc5.pdf

I have a good working knowledge of how an AC system works. How the parts work together. Have troubleshooted car and home ACs. I have close family members that are lifelong HVAC techs. Classic symptom of low gas is freeze ups if all the others are good. It's documented in many AC texts, on the Net, etc.

Having that sensor at the bottom would have done nothing in our case until the whole coil froze up.

I get that you are having a hard time being wrong but I know what ours experienced. I know and have verified the symptoms with other HVAC techs. After replacing the units the AC works perfectly so something was wrong.

1. The First Bulletin said nothing about freeze ups. Just that they had a problem with leakers on 2 percent of the units. The problem cropped up in the first year of ownership, so if you had a suspect unit after 2 to 4 years, odds are yours is OK
2. The 2nd link is 20(TWENTY) years old. The freeze sensor shown has been discontinued years ago(about 16 years). You will note that IT is installed at the bottom of the coil. YOU stated yours was in the MIDDLE, which is where the RV maker installed it, not Dometic. Sooo, if you had freeze ups on the 1st 2nd and maybe 3rd unit, LOOK AT YOUR INCOMPETANT Service person. They should have KNOWN the sensor was NOT in the correct place. At the bottom area of the coils about 1 to 2 inches up.
3. AS I STATED, if you had freeze ups, and had the Freeze Thermister and installed in the correct place, your units could not freeze up. Maybe not cool correctly but not freeze up.
4. I guess people do not need knowledgeable Service people, just look it up on the Internet. There is NEVER bad info on the Internet. Or info that when read, will be taken out of context.
5. Since you think searching the Internet makes you smarter than me, look at page 6 of this link. Doug

http://bryantrv.com/docs2/docs/ccc5.pdf

The Freeze Sensor seemed to be in a logical spot - the middle of the evaporator. It was wedged in there good so I assume it was installed by the factory that way.

I do know that if you have good airflow and it's not too cold out that it's a classic symptom of low refrigerant on both home and RV A/C's. Cars not so much as they have different controls.

Check the basics first - filters, flow, then the freeze sensor and if it's not those things then you're low on gas.

IT Guy I have been flamed for saying "Low Refrigerante" myself more than once,> But I have seen it with my own eyes mnore than once as well..

But others are correct the freeze up sensor is supposed to be stuck in the area that freezes up first and it is supposed to STOP it in it's icy tracks,

But of course,, IT may not,.

dougrainer wrote:

Sorry, IF the Freeze sensor is installed correctly, NOTHING will cause a Freeze up. I WORK on RV's for a living and have and still do for 38 years. I see more Dometic AC's in 3 months in the summer than all combined on these forums. I also NEVER see a Low charged unit. IF the unit is low charged it is because of a leak and after about 30 days the 410 or 22 will be GONE. They only hold 16 ozs of coolant. LOW charge from Dometic is almost non existant. I REPEAT my question, HOW do/did you determine they were LOW charged or had a leak? Google????? Well, The internet is NEVER wrong or has Factually inaccurate information. Doug

So then Dometic or our RV dealer installed it incorrectly. Because they replaced the unit 2x under warranty! Once in Sept 2015 and once in June 2017.

And if you do this professionally surely you are aware of this:
Dometic AC Service Bulletin

I never said it was low charged from the factory. After months of use a small leak develops and cooling performance goes down until it stops. It will start freezing up as the charge gets low and then stop cooling completely.

I direct you to Dometic's service manual It's for the R22 systems but that doesn't change the fundamentals.
Page 109-110 (1111-112 of the PDF):

Inside Coil Freezes up Causes:
Ambient Temperature C22a 59
Ducting System A6a 2
Air Flow Obstruction C22j 60
Cold Control C7 30
Heat Gain/Heat Loss C22b 59
Thermostat Location A7 12
Cable Assembly C19 52
Fan/Run Capacitor C2 28
Motor C1 27
Low Refrigerant Charge C20c 57
Capillary Tube Blockage C20a 55
Comfort Control Center C18d 52
AC Power Module Board C17c 40

I had 2 of them that failed:

#1 the cooling capacity slowly got worse until it stopped cooling. Pretty much leak then low charge there since the compressor and fans still were working (no low pressure cutout like a car).

#2 it started icing up and then cooling capacity went in the toilet- not getting the trailer to 74 when it's under 85 outside and parked in the shade. Pretty much SOP that there's no 410 in it any more.

I've got 2 AC techs in the immediate family and when we told them what was going on - check filter (clean and I even ran without it as a test) and then low gas.

Since you can't gague these units it's not 100% certain but given they seem to be failing quite regularly and Dometic says 2013-2015 units have leaking issues, it's a safe bet that the gas was gone.