Stripping out coefficients of Fourier series

Dear All,

Imagine I have some three-dimensional Fourier series like

series : (complicated_expression_1)*cos(3*z)*cos(3*x)*cos(y)
 		+(complicated_expression_2)*cos(2*z)*cos(2*x)*cos(2*y) ;

(only with rather more than two Fourier components).

complicated_expression_1 and complicated_expression_2 are free of x,
y, and z.

I know the Fourier series is zero for all (x,y,z) - from which I infer
that complicated_expression_1 and complicated_expression_2 are zero
individually.  So I'd like to do some algebraic manipulations with the
equations

complicated_expression_1 = 0 ;
complicated_expression_2 = 0 ;

but first I have to be able to extract complicated_expression_1 and
complicated_expression_2 from series.  Is there a Maxima function I
can apply to series to achieve this, please?

-- 

Thanks,

Dan