The burglars forced entry to the garage at a property on Hayton Way, just off Granville Street, at some point between 4pm on Friday and 8am on Monday.
They stole a quantity of tools and plant equipment.
A North Yorkshire Police spokesman said: "We are conducting enquiries and are requesting the public’s assistance to help determine the full circumstances surrounding the incident.
"In particular, we are appealing for information in relation to a white Ford Transit van that was seen acting suspiciously in the area at around midday on Sunday"
Anyone with information is asked to email email [email protected] or call 101, select option 2, and ask for David Gasson.
Information can also be passed on to Crimestoppers anonymously on 0800 555 111.
Please quote the North Yorkshire Police reference number 12160227840.