key fob will not activate power door locks

I had the heater core replaced on my 2201 Chevrolet silverado and now neither one of my key fobs will not activate the power door locks, or horn. The dealer says it wasn't anything that they did, but I never had a problem before the repair. The fobs are work Just an update on my problem. Took vehicle back to dealer and asked them to check RCDLR. They found that previous heater core replacement had created the problem. The mechanic never hooked the wiring back up to the RCDLR. Fixed it free of course. They spent a lot of time partially removing the dash again.