Same model, different solutions?

Hello, Community,

I'm doing phase change simulation with phase change HT module. Currently I have a problem with COMSOL:

The same model gives different results in different runs!

I use Matlab Livelink to read the solution in each run and compare the difference between two runs.

What I did in Matlab is:

% load model
Comsol_model2 = mphload(Model.mph);
% Run the Temperature model
Comsol_model2.sol('sol2').runAll;
% get model values
Temp2=mpheval(Comsol_model2,{'T2'});
Comsol_T2=Temp2.d1; % Temperature Variables
Comsol_Px2=Temp2.p(1,:); % x coordinate
Comsol_Py2=Temp2.p(2,:); % y coordinate

Comparing the above 3 variables in two simulation runs, the x and y coordinate values are exactly the same but the temperature variable varies randomly in each simulation. I expect the same solution of temperature from each simulation runs if the model is the same.

So can anyone here help me to explain this weird problem?