[Washington state] Landlord thought there was AC, there isn’t. What’s reasonable to ask for?

My landlord is a rare pretty nice guy so I’m not looking to take him to the cleaners, but I’m not sure how to handle this.

We moved in last October, so this is the first summer that we’ve tried to turn the AC on. The Zillow listing for our expensive house rental said there was central air, I checked during the viewing and his agent verified that there was AC, and we chose this house over a less expensive one in the same general neighborhood partly because there was AC (that one also didn’t have a bathtub but other things were updated that this house doesn’t have). The landlord verified that there was AC and even sent a guy out to service it. The technician looked in our utility closet and said “no AC.” The landlord never lived in this house and it seems like a genuine mistake (so how none of his previous tenants since 2018 didn’t realize, I don’t know).

We pay $4400 (4 bed, 3 bath, 1980 sqft house in an expensive neighborhood near a tech giant’s headquarters) and the other house we saw was $3800 (also 4 bed, 3 bath, and slightly larger at 2000-something sqft, slightly smaller yards, slightly farther, but still close to the tech giant). The two houses have almost identical floorplans. The one we rented is a very slightly better position in the neighborhood so we might have chosen it without AC but the price difference is pretty major.

What’s reasonable to ask for here? A reduction of a couple hundred dollars a month at least for the summer since we’ll have to be using our own units (which thankfully we already have from our previous rental that didn’t list AC)? Or ask him to provide window units for a couple of the bedrooms? Or maybe just ask him to reduce the rent by $200 when we renew the lease (which we will most definitely do because it’s a pain in the ass to move and we like this location)?

Any advice? Like I said, he’s pretty reasonable, but I don’t want to come at it with crazy demands.