I'm not an expert to give you an opinion on storing your pins inside your garage and will not give an opinion on that. But...
I've had a Tales from the Crypt in my garage for close to 2 1/2 years and have not seen signs of issues regarding the frame...
I've wonder if it does have impact on the hardware considering how hot the garage naturally gets during operational times.

I will tell you that trying to play a pin inside the garage during the heated summers is not ideal, but I still sweat it out to play.

I live in Ridgecrest, CA where average temps are 105+ for months. Inside my fully insulated garage its still 93-98. I sweat trying to play my games...

So, if you can add a portable A/C unit that will help. I have a big portable 14,000 BTU A/C unit that should exhaust out a window. Considering I do not have a window, I just want the temporary "cooling" effect I get from the A/C unit.

Maybe consider adding a window to put a Window A/C unit??