2000 Chevy Blazer 2000 Envoy bumps in road stop air cond

Electrical problem
2000 Chevy Blazer Four Wheel Drive Automatic 98,000 miles

While driving last summer when hitting bumps the air would stop till you hit a certain type of bump. It would return. Everything, heat air conditioner fan all working and checked out fine. This winter the heat started doing the same thing. Believe me its cold in the car without it. I have heated seats, thanks to ordering those. I say it is a loose connection. Don't know how to find it. Or what else can it be? Is this costly to find it. Am happy with performance etc. Otherwise. Thanks.