Farallon Capital Management is helping out an old friend squeezed by the tightening credit markets.

The San Francisco hedge fund and GSO Capital Management will buy $500 million of high-yield debt to fund private equity firm Hellman & Friedman’s purchase of heating and cooling product company Goodman Global. Farallon founder Thomas Steyer worked at the private equity firm, also based San Francisco, before starting the hedge fund in 1986, and he remains a managing director at the firm. Hellman & Friedman was also a founding investor in Farallon.

Hellman & Friedman is paying $2.65 billion for Houston-based Goodman, which returns to private equity ownership. The company, which had been owned by the Goodman family and private equity firm Apollo Management, went public last year.