Ajax does not update

Question

Can you tell me why my ajax does not update both output text fields? In my opinion, it should work well, but unfortunately, it does not.

<h:form>      
    &deg;F: 
    <p:spinner value="#{degreeBean.f}" min="32" max="62">
        <p:ajax update="f c"/>
    </p:spinner>
    <h:outputText id="f" value="#{degreeBean.f}&deg;F" />
        = 
    <h:outputText id="c" value="#{degreeBean.c}&deg;C" />
</h:form>