fan blades wont come on
 

I just got my 94 fleetwood out of the body shop. They had to take an entire front end off a 93 fleetwood and put it on mine. they had to take the fan blades off the 93 and put it one mine because mine got crushed. i noticed the fan blades werent on when i got the car to my house. i turned on the a.c and one fan came on but the other wouldnt. i took it back to the body shop and they wiggled the connector thats right before the fans. then the fan that wouldnt come on came on, but only for a couple seconds. When one came on the other would go off. Then they would both go off for a couple min untill i wiggled the connector. It wouldnt always come on when i wiggled the connector just sometimes. The car was definately hot. The guy at the body shop hooked up a meter to the connector and said it was getting power to the motor but the blades werent on. so he said "maybe" its the fan motors. A relative told me i should try replaceing the thermostat. What do you all think? by the way they told me that the car they took the fans blades out of had a bad knocking sound as if it got over heated.