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Dometic 620315 ac issue

July 26, 2024, 01:30:00 am

I have two dometic 620315 ac units on the roof of my coach. I suspect they are original but have no records to suggest otherwise

One works great but the other really does not produce much air. I took the cover off and discovered the copper piping was iced up on the poor air flow one. The one that works well does not have any ice on it

What is the issue? 

What needs to be replaced/repaired?

Suggestions?

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Re: Dometix 620315 ac issue

Reply #1 – July 26, 2024, 02:27:47 am

I would be looking at airflow. If the fan output becomes low it will freeze up. I also had service ports welded in to add Freon. Worked great. The seals inside the covers are also important to prevent bypass air flow threw the condenser or evaporator

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Re: Dometix 620315 ac issue

Reply #2 – July 26, 2024, 08:44:26 am

Run the fan on high and insure the filter is clean.

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Re: Dometic 620315 ac issue

Reply #3 – July 26, 2024, 10:35:15 am

These are all good suggestions.  Icing of the evaporator coil can also  be an indication of low refrigerant charge.  Having access valves brazed into the system as Scott suggests is a good idea. Then the charge could be verified with a manifold gauge set.  You could also use an electronic refrigerant gas detector to check for leaks.

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Re: Dometic 620315 ac issue

Reply #4 – July 30, 2024, 10:49:24 am

So I have been running it for the last few days. It seems that initially when I put it on, either low med or high it responds ok. Then after running a few hours it gets louder and the cool disappears somewhat. The fan still runs. I have not seen where there is a place to do the coolant. Maybe missing something?  It looks like a sealed u it that refrigerant can't be added.

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Re: Dometic 620315 ac issue

Reply #5 – July 30, 2024, 12:32:18 pm

It is a sealed system. Some have installed a port to add Freon.

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Re: Dometic 620315 ac issue

Reply #6 – July 30, 2024, 12:34:14 pm

I am assuming the filter is clean as it can cause the same symptoms.

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Re: Dometic 620315 ac issue

Reply #7 – July 30, 2024, 01:35:56 pm

Filter is brand new. Replaced both just a few days ago. The front ac is running great. It is just the rear ac

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