A/C unit old, home warranty claim denied, do we have a case?

[Jeff And Vishi]

Hi All, i hope i am posting this at right place, please advise if this should be posted else where, if so where? My partner and I are small investors in 2 properties in Phoenix, AZ. We have home warranties on both. Our A/C unit on top of the roof is not putting out heat. we got a call from the tenant. Home warranty dispatched a company to us. A/C repair company decided that there was sprayed on the unit (pictures attached). We did not spray this foam. Insurance should have checked all this, before they started coverage correct? Have you run into similar situation? let us know what is your advice?

Thanks