CNG does not freeze at such temp (8~11 C), freezing point of mathane is -182.5 C, secondly, an interesting fact is gas cannot directly convert to solid(frozen form), first it will change it's form to liquid, I admit compression does change the properties/appearance but it also increases the temp. of gas molecules, simple check is insert ur finger in the back hole (manual choke) of CNG kit and slightly press, u'll listen to a hissing sound, actually what u do is to squeeze the diaphrams of kit and letting the gas go trapped inside them, now s/w on the ignition key, the 2 relays will sound and gas has again come to the kit, u can repeat ur actions again to see, CNG is really in gaseous state.
The things one needs to care about are, CNG kit(regulator) choke setting is ok, means it's working fine, no oil in kit (should be drained regularly)and the tunning (A/F) is properly done. as it requires a good spark to burn cng so all other rules of keeping CNG veh. apply too. e.g. spark plugs, air intake, timing etc etc.
