First Chicago Corp., parent of the troubled First National Bank of Chicago, said yesterday that its fourth-quarter earnings plunged more than 30 percent last year, partly as a result of higher interest expenses during the three-month period.

In San Francisco, Bank of America -- the nation's largest commercial bank -- said its final-quarter profits rose 2 percent to $160.8 million ($1.09 a share) from $157.6 million ($1.07) in the comparable period in 1979.

In New York, Chase Manhattan Corp. reported a slight increase in its fourth-quarter profits, while in San Francisco Crocker National Corp. said its earnings for the final quarter of 1980 rose 2 percent.

First Chicago, which has been plagued by sagging profits for more than a year, said its earnings dropped to $12.2 million (31 cents) in the quarter from $17.5 million (44 cents) in same 1979 period.

First Chicago spokesman Bill Baldwin said the company attributed its lower earnings largely to a decline in its net interest spread -- the difference between what it earned on loans and what it paid out on deposits. He said operating expenses also were higher.

For the entire year, First Chicago's earnings dropped more than 42 percent to $66.5 million ($1.68) from $115.4 million ($2.91) in 1979.

Meanwhile, Bank of America said its earnings for the full year jumped to $645 million ($4.39) from $600.2 million ($4.10) in 1979. Chairman A. W. Clausen attributed the 1980 gains to significant increases in the bank's loan volume.

Chase Manhattan Corp., parent of the country's third-largest bank, said earnings for the final quarter of 1980 rose to $77.1 million ($2.12) from $76.7 million ($2.23) in the comparable quarter in 1979.

For the full year, Chase said its earnings rose to $364.7 million ($10.47) from $311.1 million ($9.07) in 1979.

Chase also announced an increase in its quarterly dividend to 77.5 cents, from 70 cents, payable Feb. 15 to shareholders of record Feb. 2.

Chase President Williard C. Butcher cited the high level and volatility of interest rates, especially in the final quarter, and said "all things considered, we feel it was a good year for the Chase."

Crocker National Corp., whose principal holding Crocker National Bank is involved in a proposed merger with Midland Bank of London, said its fourth-quarter earnings rose to $26.4 million ($1.85) from $25.9 million ($1.91) in the final quarter of 1979.

For the full year, Crocker's earnings jumped to $95.1 million ($6.72) from $89.3 million ($6.69) in 1979.

Crocker is the nation's 13th largest bank.

Despite poorer earnings by two major divisions -- National Broadcasting Co. and Hertz Corp. -- RCA Inc. had record profits and revenues in 1980.

RCA's earnings for the year were up 11 percent from 1979 levels at $315.3 million ($3.35 a share) on sales of $8.01 billion compared with $238.8 million ($3.72) on sales of $7.45 billion.

The 1980 results include those of CIT Corp. on an equity basis. The company said that without the contribution of CIT earnings, both the parent firm's net income and its per-share earnings would have been down from a year ago. There also were more shares outstanding in 1980. Startup costs of the SelectaVision videodisc program and high interest costs also slashed net income.

Fourth-quarter profits rose 13 percent to $79.1 million (82 cents) on sales of $2.09 billion from $70.1 million (also 82 cents) a year earlier on sales of $1.98 billion.

General Foods Corp., the maker of such products as Maxwell House coffee, Kool Aid drink mix and Cycle dog food, said yesterday that increased coffee sales helped boost earnings in its third fiscal quarter to $59.6 million ($1.20 a share) from $52.5 million ($1.05) a year earlier.

The company said sales for the three months ended Dec. 27 rose 3.8 percent to $1.58 billion from $1.52 billion.