A group of 32 advisers have vowed not to return to the bureau until the dispute, which began after a volunteer was asked not to return because of bullying allegations, has been resolved.
The walkout has left only three volunteer advisers supporting the paid workforce of 20.
The stay-away group claims that the individual, who has served at the bureau for several years, was summoned to a meeting on 14 May at which he was told that allegations of bullying and harassment had been made against him and he should not return.
According to his supporters, the volunteer was not told the precise nature of the allegations and was therefore unable to mount a proper defence.
Chris Hailey-Norris, director of York CAB, said the bureau still had about half of its volunteer workforce. But he was unable to comment on the appeal that has been lodged by the volunteer.
"We are halfway through a process and we hope that the situation will be resolved soon," he said.
According to Hailey-Norris, the walkout had made it harder for the bureau to maintain its services at former levels.
"It is about juggling resources and doing the best we can, as we always do," he said.
One of the volunteers, who asked not to be named, said: "It is outrageous that an organisation that purports to represent people's rights and help people to defend those rights should itself be behaving in such a manner.
"The trustee board and the director have been so intransigent that we are getting to the point where we are wondering if we can ever return," the volunteer added.
Hugh Bayley, Labour MP for the City of York, wrote to the CAB management to urge that the 'sacked' volunteer be given a fair hearing.
A spokeswoman for Citizens Advice, the national body that represents individual bureaux, said: "We very much hope that the problems at the bureau can be resolved quickly and fairly."
The volunteer's appeal against the decision will be considered on 15 July.