AC Evaporator cleaning question

[Sailor John]

Good morning!
I had my 16K Cruiseair AC system in the salon recharged over the weekend.
It blows very cold now, but is icing up. We had high humidity the last few days, but the 12K aft/v-birth cabins system is and always has run quite well, with no icing.
The AC tech says all is well with the system despite it 43 years, (Amazing!) but as there is no filter on the air intake, the evaporator coil is likely clogged and not getting enough air blowing over it, causing the ice buildup. Even on high fan speed.
The question of course is how to clean the back of the evaporator coil when it is totally inaccessible. (due to cabinetry). I have reviewed Hatteras forums and found product like Viper Brite recommended, but somehow spraying a wet foaming agent seems to me to be not the thing that would work best as wet dirt clings better than dry dirt.
Here is what I propose, and tell me if you think this would work:
Basically, a backwash of the air. With the system off, I would attach a shop vac to the fan intake to suck air backwards, and blow canned compressed air (like the product you find for computers) through the evap. coil from the front, creating a complete reverse flow of air. Hopefully, the canned air blast would dislodge the dirt, and the vacuum would suck it backwards of the system.
Does this make sense, or am I smoking dope?
Thanks,
Sailor John.

 

[Boatsb]

put the pipe down.

The cleaners are made for the job. Dont reinvent the wheel. It will wash down to the drain pan and out the drain.

 

[TROUBLE]

I did mine with the spray foam and after letting it sit rinsed it with a water spray bottle. Worked out great

Art

 

[Sailor John]

Appreciate the insights.
I just have a hard time understanding that 40 years of unfiltered air could be disloged by a spray product. I am of course willing to try it. It seems easier than what I propose.
Sailor John

 

[Timeout]

I just used a compressor and spray nozzle and blew it out with shop vac running. Kind of messy but it worked fine. I'm sure there is some reason not to do this but I've never had a problem.

 

[Walter P]

Kevin, Your procedure works......but you are taking a chance using compressed air against the relatively fragile fins of the evaporator coil. They bend pretty easy and if that does happen you will restrict the air flow. Most HVAC supply companies sell a "fin comb" which can straighten out the bent over fins. Although your procedure works and obviously improves the air flow, a follow up application of coil cleaner and a good rinse completes the job. Compressed air blows out the fairly loose particulate but the schmutz that is clinging to the coils needs to be washed as it serves as an insulater.

You're half way there. Follow up with a coil wash, be sure your drain is clear and by all means install a filter that can be cleaned or replaced from time to time.

Walt

 

[Sailor John]

Hello all,
I used a foaming coil cleaner by Frost King on all evaporators today. It was simple enough to use and I did each evaporator twice. It was a bit messy but the foam eventually dried up and there was no residual mess. I hope it works!
I also vacuumed the condensate lines with a shop vac and a small funnel, just to help the draining process. It’s surprising how much condensate water actually builds up in the sumps.
I appreciate all the help,
Sailor John