Radiator Fans

[WGJ]

my A/C fan, (drivers side fan) does not work. The fan just wobbels to the touch, doesn't spin. Appears to need replacement but I haven't taken it apart to see if it might be repaired. AC tech says that it will cause pressure to build in the system (260 lbs?) while in stop and go traffic on a hot day (90+).
Does this make sense?
Fans appear pretty easy to replace...where can I get them and do they both have to be replaced? Looks like one plastic piece holds both fans in place(?).
Thanks,
WGJ

[Earthworm]

You can try swapping sides just to verify that it's in fact the fan and not a relay or something else.