Regassing portable airconditioners

[elanjacobs]

With the weather getting hotter the aircon is out and it feels like the air coming out of it isn't a cold as it was last summer. It's an older Dimplex 8000 BTU unit.
Is there a) any way to test if it's working a full capacity and b) regassing it if it's not?

[Chief Tiff]

Hi Elan, the chances are that your portable AC is an hermetically sealed unit so there won't be any joints for gas to leak from. Additionally performance testing refrigeration systems requires specific measurements of system pressures and temperatures; again this won't be possible.

What does kill the performance of AC units is dirt; the coils in the evaporator and the condenser get gummed up with dirt, grease, mould etc and this effects the rate of heat transfer by acting as an insulator. Plus sufficient dirt will restrict the air flow through the fins, mould is a beauty for doing this.

As you're not unaccustomed to pulling machinery apart strip the unit down sufficiently to gain access to the two coils and their fans. Wipe the fan impellors to clean them and blow thorough the coils with compressed air. If they are visibly filthy then you can clean them with a mild alkaline cleaner and blow them dry, or possibly a volatile solvent such as brake cleaner. Same as a DE; make sure all airflow is impeded as little as possible.

There are very good commercial products such as "Viper" which you can basically just spray into the running unit, but these are spectacularly expensive. The spray can in the link will set you back around $40 from Actrol; it's good stuff but designed to allow a tech billing at $70/hour to spend no more than a minute or two cleaning coils. If you were to take the whole unit to an air con installation and maintenance company for a service all they would do would be to take an initial set of air in/out temperatures, possibly measure the running current and then chuck Viper or similar through it before repeating the measurements and wiping it down.

[AlexS]

That's what I like about this place. One direct question, a couple of hours later, an informed, succinct answer.

[elanjacobs]

Thanks for that
As far as I can see with a torch through the vents, everything is spotless, but I'll pull the case off when I get back from interstate and have a proper look.