The Hechinger Co., apparently enjoying the fruits of economic pressures on homeowners to fix up rather than trade up, report sales and earnings for the first quarter of 1980 yesterday.

Sales increased 23 percent to $40.7 million compared with $33.1 million during the same period in 1979. Net earnings rose 42 percent to $1.2 million (30 cents a share) for the quarter ended May 3, compared with earnings of $863,980 (21 cents) for the same period last year.

Hechinger President John W. Hechinger and Chairman Richard England attributed part of the gains to home repairs made by owners anxiour to protect their investments. They noted that the company experienced a 16 percent sales increase without taking into account the firm's additional stores during the period and also pointed to the fact that costs and expenses as a percentage of sales were lower.

The company also benefited from not having to borrow during a period of record high interest rates, the two store officials said.

The company will pay a previously announced quarterly cash dividend of 3 cents a share and a 20 percent stock dividend on May 30.

The Arundel Corporation of Baltimore announced net loss in the first quarter of 1980. Net earnings declined from $2 million in the quarter ending March 31, 1979, to a loss of $1.2 million (75 cents) in the first quarter of 1980.

Officials of the construction and real estate firm blamed the downturn on bad weather hampering operations in Tidewater Virginia and coastal North Carolina operations. A decline in economic activity on the Eastern Shore of Maryland also ate into earnings, they said.

The Student Loan Marketing Association (Sallie Mae) announced that first-quarter net income rose 26 percent to $2.4 million ($14.17 a share) from $1.9 million ($11.25) in the same quarter of 1979. Program assets, including student loans purchased and warehousing advances to lenders in the Guaranteed Student Loan Program, rose 75 percent from $989 million in the quarter ended March 31, 1979, to $1.7 billion at the end of the same quarter this year.

Sallie Mae was created by Congress in 1972 to provide a seconday market for guaranteed student loans.