Colleges Take in Summer Lodgers Across North America : Schools fill empty dormitories by renting to travelers. Two directories list current offerings.

This summer, budget-minded travelers can sleep in a single room in Paris or London for $17 per night, in Vancouver for $15, or in Phoenix for as little as $10. It happens ever year during school holidays when hundreds of universities and colleges in North America and abroad scramble to fill empty residence rooms with groups and individual travelers.

In Toronto, for example, Neill-Wycik College will accommodate travelers until late August. Guests are being offered a “backpackers’ rate” of about $15 per person, per night, in rooms shared by up to two people. Single rooms (with breakfast) will be available for about $24, twin and small double rooms for $29. Family rooms will cost $38.

Getting a break on rates can mean having to share a bathroom, and in some cases provide your own linens or rent them. There can be some advantages, though, such as the use of sporting facilities (pool, running track, gymnasium, etc.), convenient parking and economical food services.

The most comprehensive source of information on university residences that accommodate travelers is the 1993 edition of the “U.S. and Worldwide Travel Accommodations Guide.” It lists 421 campuses in the United States and 92 in Canada that offer lodgings, usually for $15-$30 per night. You’ll also find listings for London, Paris, Berlin, Copenhagen, Jerusalem, Vienna and other capitals in Europe, New Zealand and Australia.

Each listing includes room rates, dates available, facilities offered at the university, activities in the area and a contact for reservations.

North America listings include 27 campuses in California, 20 in New York and a total of 10,000 rooms across Canada. Examples:

* Warner Southern College in Lake Wales, Fla. (near Disney World, Sea World and Circus World) offers air-conditioned single rooms for $15 and double rooms for $20 through Aug. 15.

* Catholic University in Washington, D.C., offers single and double rooms for $18 ($14 without air conditioning) through Aug. 30.

* In Vancouver, the University of British Columbia offers single rooms for $15-$24 and double suites for $48 through Aug. 26.

* Dalhousie University in Halifax, Nova Scotia, offers singles for $20 and doubles for $32 at its Fenwick Place residence through Aug. 15.

* McGill University in Montreal rents up to 900 rooms through Aug. 15. Non-students can get a single room for $36.50; students with ID cards are charged $26.50. Children are welcome.

The “U.S. and Worldwide Travel Accommodations Guide” also includes tips on stretching travel budgets, a list of YMCA lodging centers plus helpful contacts such as home exchange programs, European home- and farm-stay organizers and tourism board contacts.

Copies may be available in your local or campus library. You can order a copy for $14 from Campus Travel Service, P.O. Box 5486, Fullerton 92635, (714) 525-6625.

A second, less comprehensive, pocket-sized booklet, “On Campus--USA and Canada,” lists 225 campuses throughout the United States and Canada that welcome travelers. It is available for $8 from Keys Enterprises, Box 130, Grafton, Ontario, Canada K0K 2G0, (416) 349-3460.