Flushing Evaporator Coil

[bp73]

I've repaired many AC systems in the past on older vehicles and it's always been the rule of thumb to replace the condenser coil and flush the evaporator coil. The condenser coil passages are just too small to successfully flush out all debris. With that being said, I was told that the newer evap coils used in 4th gens had smaller passages similar to the condenser and could not be flushed and needed to be replaced. Can anyone confirm or deny this? Has anyone performed a flush on their 4th gen evap?

 

[Fast69Mopar]

I've repaired many AC systems in the past on older vehicles and it's always been the rule of thumb to replace the condenser coil and flush the evaporator coil. The condenser coil passages are just too small to successfully flush out all debris. With that being said, I was told that the newer evap coils used in 4th gens had smaller passages similar to the condenser and could not be flushed and needed to be replaced. Can anyone confirm or deny this? Has anyone performed a flush on their 4th gen evap?

I have successfully flushed many, many 4th Gen RAM evaporators. There have only been a few that I have not been able to save. The biggest problem I have with the evaporators in the 4th GEN trucks that I have had in the dealership is the amount of dirt and debris that can accumulate on the inlet side causing a restriction in airflow to the vents. They can get really dirty in a very short period of time.

 

[chopperman1]

What debris? It is a sealed system. The filter/drier catches anything that may be from manufacturing. You also have a fine mesh strainer on the inlet of the orifice. 25 years as a master HVAC tech and the only flushing ever done is from an acidic burnout of a hermetic compressor.

 

[Fast69Mopar]

What debris? It is a sealed system. The filter/drier catches anything that may be from manufacturing. You also have a fine mesh strainer on the inlet of the orifice. 25 years as a master HVAC tech and the only flushing ever done is from an acidic burnout of a hermetic compressor.

Unfortunately not all of the fine metal and any type of debris gets caught by the desicant in the accumulator or receiver/drier. Some of the compressors used in the 2010-2014 model year trucks were not the best quality and the quality control wasn't great either. Some of the debris I am referring to was in the form of very fine aluminum shavings from the piston. There was a STAR Case in 2013 from the Dallas zone that referenced compressor failure and subsequent debris in the system and the repair called for a new compressor, expansion valve and receiver/drier as well as flushing the condenser and evaporator. If we were unable to flush the condenser and evaporator and get the correct pressures then we replaced them both.

We still have a part number for the A/C flush chemical. I have used it multiple times.

 

[bp73]

What debris? It is a sealed system. The filter/drier catches anything that may be from manufacturing. You also have a fine mesh strainer on the inlet of the orifice. 25 years as a master HVAC tech and the only flushing ever done is from an acidic burnout of a hermetic compressor.

The debris from the failed compressor. This model truck has no orifice valve/tube. Once I pulled the expansion valve (which on this truck is located right on the firewall connecting directly to the evap) off, black oil ran out and was full of metallic compressor "disco dust".

 

[bp73]

I have successfully flushed many, many 4th Gen RAM evaporators. There have only been a few that I have not been able to save. The biggest problem I have with the evaporators in the 4th GEN trucks that I have had in the dealership is the amount of dirt and debris that can accumulate on the inlet side causing a restriction in airflow to the vents. They can get really dirty in a very short period of time.

Thanks for the info. As far as the airflow restriction; what have you determined the cause to be?

 

[Fast69Mopar]

Thanks for the info. As far as the airflow restriction; what have you determined the cause to be?

Man, for some reason these trucks allow so much dirt and lint and just crap into the HVAC housing causing the airflow restriction. Having a pet in the truck a lot makes it worse. On my 2010 and 2011 RAM 3500's I made a modification to the HVAC housing on the right side of the evaporator where I could slide a metal screen in front of the evaporator so that way when I got dirty I could slide out and clean it.

I see more and more 4th GEN trucks with poor airflow from the vents and the absolute majority are from an externally restricted evaporator coil.