Grenade saves on special effects

[Black Lamb]

I know that when a grenade goes off and you make your reflex save you don't take the special effects like staggered, but if you fail the reflex save do you then to the save for the condition as it's listed in the weapon critical hit effects section?

Example:
You are in the damage area of a Cryo grenade, and save your reflex save so you take full damage and then roll a fortitude save to see it you become staggered or not. Or is the reflex save it and there is only one check for seeing if you take the special effect.

[avr]

Since that's a critical hit effect it applies only when the person throwing the grenade (or firing the grenade launcher) rolls a 20 and it's a hit. Which may seem odd considering that you're targeting a grid intersection, but them's the rules I think. If I'm right then on a critical hit people caught by the cryo grenade roll two saves, one fort vs. staggered, one reflex to halve the (doubled via crit) damage.

[Vexies]

avr wrote:

Since that's a critical hit effect it applies only when the person throwing the grenade (or firing the grenade launcher) rolls a 20 and it's a hit. Which may seem odd considering that you're targeting a grid intersection, but them's the rules I think. If I'm right then on a critical hit people caught by the cryo grenade roll two saves, one fort vs. staggered, one reflex to halve the (doubled via crit) damage.

Not quite, Critical hit effects happen if you roll a critical hit with no save. The only save you would roll is the save vs damage of the grenade itself. Grenades that have additional affects work differently page 183 states the following:

Some grenades have additional effects, such as blinded or entangled, that apply only to creatures in the explosion radius that fail a Reflex save against the grenade.

So in the case of grenades with secondary effects. Staggered, Entangled etc. those affects happen if you fail your save vs the damage of the weapon no crit roll needed.