The suit, which was filed in Illinois, claims Wells Fargo failed to accurately assess the value of customers' houses before deciding to cut the size of their credit lines. San Francisco-based Wells Fargo is being accused of using unreliable computer models that wrongly valued home prices too low to justify cutting the size of customers' loans.

Home equity lines of credit are similar to credit cards in that a customer has a credit limit and can continue to borrow money until the limit is reached. Once a portion is paid off, it again becomes accessible to borrow. But, home equity lines of credit are backed by a borrower's property, whereas credit cares are unsecured.

Michael Hickman, who filed the lawsuit on behalf of himself and is seeking class action status for it, claims Wells Fargo also did not provide proper notice that the bank was reducing the size of the credit lines.

The bank's notice for reducing the lines also did not specifically provide a new estimated value for the property or the method used to determine the houses value. Hickman's lawsuit said that information was needed so a customer could challenge the change in the credit limit and try and reinstate the previous limit.

Hickman is being represented by KamberEdelson LLC, a Chicago-based law firm, which is also representing clients that have filed similar suits against JPMorgan Chase & Co. and Citigroup Inc.

Nearly all banks have been hit hard by mounting loan losses tied to residential real estate over the past two years. Reducing lines of credit can limit exposure to the struggling sector.