The AC was running for over a month with no filter, now it freezes up frequently and I'm wondering if there's a way to clean it without calling someone for repairs.

Basically the above. We bought a house and neglected to check that the intake had a filter. The AC was newly installed on the house so we thought we had nothing to fear. About two weeks in the AC starts freezing up, only then do we realize that there are 3 intakes that need filters that were converted from old swamp cooler outputs, non of which had filters. Because the trust we bought the house from had other contractors working on the roof and HVAC any warranty we had on it was voided. From what I can tell it's a bud up fo dust and dirt causing the freeze ups but I wouldn't know where to start looking for that build up or how to go about cleaning it out.