"AC service" recommended by dealership... is that something I can do myself?

You’ll need to clarify “AC service”.

If it’s a cleaning of the in-dash ductwork, to clean mildew/mold, that’s one thing, and $99 is probably the going rate.

If it’s an evacuation and recharge of the system, due to poor cooling performance, $99 USD is quite a good deal.

are you having either of the aforementioned issues? If not, my 2 cents: they’re just trying to drum up business.

FWIW there’s no AC service interval spec by Toyota USA, it’s basically service as needed.

 

The typical $99 AC cleaning involves a foaming cleaner. Comes in a spray can with a hose attached. You go under the car and hook it up to the condensation drain tube, then set it off.

The product goes up the drain tube, foams up inside the evaporator/heater core area (which is otherwise very inaccessible) and generally pushes any dirt or debris upwards through the vents.

The foam dries and disappears after.

So there is a bit of inconvenience getting under the car, and then cleaning the interior after dirty foam comes out the vents, but that's it.

If you have kept up with cabin air filter replacement, then the evaporator and heater core aren't likely to be that dirty in the first place. In most systems that filter does a good job of stopping dust before it can cake onto the heat exchangers.

 

The OP needs to watch this YouTube video from The Car Care Nut.

 

AC systems run constantly are prone to develop mold. One trick, but it takes some discipline, is to shut it off at least a mile before your destination, run the windows partially/fully down, keep the fans running. This gives the humidity (primarily on the evaporator fins) time to evaporate.

I know, easy to say in the Great White North. It is getting toasty up here too; Coquitlam's predicted high today is 32 C, and summer's just getting started.

 

I’d ask what they propose to do, and why they think it’s needed; it shouldn’t be a mystery. I wouldn’t be surprised if they were suggested that to every service customer.

 

That is probably the same foaming cleaner substance, but I suspect it would be difficult to use simply because it hasn't got the hose attachment that commonly comes with the automotive version.

The kind I've successfully used in the past has a short hose and usually a plastic tip that can be wedged into the condensation drain tube, which hangs down from the passenger footwell area near the right front tire. Trivial to access for a shop with a lift, trickier without.

If you haven't got the hose connection, I can't imagine holding the can in place long enough/well enough to actually get the product through the tube to where it is needed. Probably wouldn't be fun to be half under a car with foam spraying all over.

If you are worried about junk coming out the vents, you could tape some trash bags to the dash under the vents, or maybe have a vacuum cleaner with hose attachment standing by to catch it as it comes out once you've set off the foamer. The worst of it is generally decayed leaf fragments that washed down through the fresh air inlet under the right-hand windshield wiper.

 

This concern was precipitated by a service writer suggestion; maybe just following a “script”. Are there any odd smells? If not I’d skip it.

The main reason mold develops in AC system is near-constant use, in particular shutting the car off and letting it sit with system full of humidity.

 

In a car with a cabin-air filter, that kind of stuff shouldn't be getting to the blower, evaporator, or ducts (unless some fell off during a filter change).

I had an old Ford from the pre-cabin-filter days, where the blower was very efficient at mulching leaves into a coarse powder and packing it firmly under air pressure into the evaporator fins.

I took that evaporator out and let it sit most of a week in a trash can filled with warm water and the enzymes you buy to keep septic tanks clear. Then used a pressure wand to blow the goop out. Came out nice.

 

I agree. But, having had to clean a little of that out of a then-8 year old car that did have a cabin air filter I felt like it was fair game to mention. I reckon it got through as you say, during a filter swap.

 

Curious ? On a 85°F day is the suction line cold sweaty and wet with condensation? All the way back to the compressor.