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Old 06-26-2022, 03:32 PM   #1
dietzldub
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AC Unit Freezing Up

We have a 2018 Cougar 366RDS and the rear AC unit coil will freeze and the ice at the bottom of the condenser will prevent the water from draining properly causing some of the condensation moisture to drip onto the floor inside. Running fan on high all the time.

The coils are clean no dust or dirt on the coil. It puts out very cold air but freezing up.

What are your thoughts? Would they need to break into the system to charge it?
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Old 06-26-2022, 03:44 PM   #2
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We have a 2018 Cougar 366RDS and the rear AC unit coil will freeze and the ice at the bottom of the condenser will prevent the water from draining properly causing some of the condensation moisture to drip onto the floor inside. Running fan on high all the time.

The coils are clean no dust or dirt on the coil. It puts out very cold air but freezing up.

What are your thoughts? Would they need to break into the system to charge it?
ac units usually freeze up for one of three things…. 1)low charge…2) restricted metering device ..(piston or txv)….or 3)….inadequate airflow…could be #3…blower motor or capacitor could be bad or failing or ductwork may be blocked or collapsed…maybe check for loose tape or something blocking the ductwork..or a very dirty air filter.

if you need to break open the system to charge it you’ll need someone with a vacuum pump before adding refrigerant…they make some really nice push connect fittings just like shark bite fittings for ac systems…i used some two weeks ago on a job that had a sprinkler system in a tiny equipment room

edit: residential ac systems freeze from one of three things (usually)…i keep forgetting we are talking rv air conditioners that operate under different parameters and have the supply and return so close to each other and sometimes are used well below temps that would be considered normal at home….also the freeze sensor is mostly not used on residential systems.
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Old 06-26-2022, 03:45 PM   #3
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Two things I can think of. 1. Temp set high 2. low freon (or what ever they call the stuff now). #2 means a leak and likely new A/C.

I have had my A/C freeze up when I have set the temp at 80F and low speed on the fan to keep things from getting too hot in my camper on very hot and humid days. Also make sure if you have a filter down below, it is clean.
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Old 06-26-2022, 05:13 PM   #4
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Make sure the freeze sensor is installed correctly. Mine was not installed and just left coiled up.
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Old 06-26-2022, 05:29 PM   #5
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Make sure the freeze sensor is installed correctly. Mine was not installed and just left coiled up.
This, and they can fall out.
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Old 06-26-2022, 07:51 PM   #6
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Thank you guys.

The filter is clean, double checked for any debris. All looked good as far as that.

What does the freezer sensor look like! I do remember seeing a probe type of thing sticking in the coil.
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Old 06-27-2022, 02:54 AM   #7
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Thank you guys.

The filter is clean, double checked for any debris. All looked good as far as that.

What does the freezer sensor look like! I do remember seeing a probe type of thing sticking in the coil.

That's probably the freeze sensor. Mine's black and about 1/8" diameter.
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Old 06-27-2022, 05:18 AM   #8
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The freeze sensor is typically just stick in between the evap coils .. usually dead center ..

Check the placement of your freeze sensor

Also you cannot recharge the RV coolant… at least not easily and most RV TECHS wouldn’t have the equipment to do so..

It is a sealed system with no charging port .. yes one can be added but I wouldn’t fool around with that approach
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Old 06-27-2022, 06:57 AM   #9
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Recharging a hermetically sealed cooling unit is a short term temporary solution. If the refidgerant charge is low that means only one thing, there's a leak. If you don't fix the leak then just adding refridgerant is like trying to carry water in a spaghetti strainer.
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Old 06-27-2022, 06:11 PM   #10
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Recharging a hermetically sealed cooling unit is a short term temporary solution. If the refidgerant charge is low that means only one thing, there's a leak. If you don't fix the leak then just adding refridgerant is like trying to carry water in a spaghetti strainer.
And, you can probably replace the unit for what it costs to do a proper repair job. Saddle valves are for punks and optimists.
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Old 06-28-2022, 03:39 AM   #11
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What refrigerant does our RV ACs use?
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Old 06-28-2022, 04:32 AM   #12
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And, you can probably replace the unit for what it costs to do a proper repair job. Saddle valves are for punks and optimists.
saddle valves are junk for sure..but these new push connect fittings definitely work..i used a couple in a tight equipment room that had sprinklers in a townhouse community. I have been in the hvac industry since 1984.
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Old 06-28-2022, 04:34 AM   #13
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What refrigerant does our RV ACs use?
r410a is what replaced r22
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Old 06-28-2022, 05:20 AM   #14
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sometimes leaks are very easy to find…look for oil residue…if a unit is less then 5 years old then the leak could be from a copper line rubbing against the frame of the ac unit…in that case you can cut the piece out an put a push connect coupling in its place…you can buy small bottles of 410a and i think HF sells small vacuum pumps…weigh the 410a into the system if you want to be exact..but you can charge until the suction line flashes cold and be pretty close…i wouldn’t even try to charge a 10 or 15 year old unit but why not try and fix something with an easy to fix leak…me personally i’d just braze over the hole in the copper line but i have all the tools and knowledge to make repairs
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Old 07-01-2022, 03:13 PM   #15
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The freeze sensor is in there, however the ice never got as high as where the sensor was located. I moved it down some so it will be at the upper area where the ice was building up. Hope that didn’t hurt anything.
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Old 07-01-2022, 03:16 PM   #16
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Thanks Jasin. I’m heading out of town for the weekend, when I get back I’ll open it up again and take another look for oil residue. Thank you
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Old 07-03-2022, 07:55 AM   #17
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Originally Posted by dietzldub View Post
We have a 2018 Cougar 366RDS and the rear AC unit coil will freeze and the ice at the bottom of the condenser will prevent the water from draining properly causing some of the condensation moisture to drip onto the floor inside. Running fan on high all the time.

The coils are clean no dust or dirt on the coil. It puts out very cold air but freezing up.

What are your thoughts? Would they need to break into the system to charge it?
I have a 2019 Cougar 315RLS that had the same problem with the rear AC. Had it checked by the dealer's mobile repair several times with no luck.
The last guy to check it opened it up from the inside and applied some duct tape (proper foil type) and told me the intake air side and the output to the ducts wasn't sealed properly at the factory. After he was done it seemed a little better but still froze up.
So the following year I decided to check for myself, watched a few YouTube videos first, purchased the proper duct tape and sealed up the AC between the air intake and the air output as well as I could. The previous tech missed a lot!
Haven't had a problem since I did that, here is a YouTube video to give you an idea, mine was a Dometic and not the same as in the video but the idea is the same, hope this helps, good luck!

I did try to relocate the freeze sensor first but it didn't help.

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Old 07-03-2022, 01:16 PM   #18
dietzldub
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I have a 2019 Cougar 315RLS that had the same problem with the rear AC. Had it checked by the dealer's mobile repair several times with no luck.
The last guy to check it opened it up from the inside and applied some duct tape (proper foil type) and told me the intake air side and the output to the ducts wasn't sealed properly at the factory. After he was done it seemed a little better but still froze up.
So the following year I decided to check for myself, watched a few YouTube videos first, purchased the proper duct tape and sealed up the AC between the air intake and the air output as well as I could. The previous tech missed a lot!
Haven't had a problem since I did that, here is a YouTube video to give you an idea, mine was a Dometic and not the same as in the video but the idea is the same, hope this helps, good luck!

I did try to relocate the freeze sensor first but it didn't help.


That’s great info, thank you for sharing the video, and note about the freeze sensor. I’ll check it out when I get back home tomorrow. Hopefully I’ll see that’s a good possibility of being the problem.
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Old 07-05-2022, 05:10 PM   #19
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Well the unit did some gaps from the warm side to the cold side. Here are some pics, you can see my finger tips in a couple of the pics. I did seal them off with some aluminum duct tape. It’s been running for about 90 minutes and doesn’t seem to be freezing up. It is very humid hear in eastern South Carolina.
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Old 07-05-2022, 07:22 PM   #20
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Bigrock, thank you for sharing the video. It ran for a few hours tonight and no dripping it looks like it took care of it. It was totally dry.

It’s such a luxury having the RV in the back yard with a 50 amp pedestal to plug into. I ran power out to it about 2 years ago.
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