Silicon circuits are temperature sensitive per design; there’s a kT/q factor that keeps appearing in equations…
…so you often see 26 mV (or 19.2) popping up, but the exact value varies with temperature in the real circuit.
However, oscillators are usually designed to compensate for this, either by using components with opposite temperature characteristics in the control voltage circuitry (e.g. tempco resistors) or having different active components pull in opposite directions, and place them in direct contact or on the same silicon (the 3340 uses the latter approach). But there will always be some drift.
(for VCAs and other circuits, there’s usually less compensation and more “deal with it, it’s analog gear”)
But I’m not convinced fans will do much; the thermal effects happen at the junction level, long before the heat reaches the component surface and starts heating up the ambient air.
(you could heat up the entire oscillator (cf OCXO oscillators, or precision circuits with built-in heaters) but that may be a bit trickier to experiment with 
)