85 300SD, CCU(climate control unit - the push button) "clicking" noises. Only happened during cooling cycle, and only when the temp got to the point of regulation, when the CCU switches on/off to regulate temp in cabin. Was worse with bumps in road, even braking would increase clicking.
Clicking was the internal "points" type switches in the CCU itself.
This was a rebuilt CCU. Figured it was a loose connection somewhere. But why would it do it only after A/C got to the regulation point and not all the time?
Pulled console cover, checked all wires. It's almost impossible for a wire to be loose there, everything is wrapped solid. Checked and pinched connectors for both sides of CCU. Still did it.
Checked Temp Sensor, near dome light. Working fine.
Checked Temp Regulator. Right side panel under glove compartment. Found that moving it would cause the problem. Pulled connector and checked and pinched connectors. Held wire harness tight against box and seemed to solve the problem. :p Taped the harnes tight there and replaced. So far, so good.
Maybe a bad connection or loose wire at the Temp Regulator was prohibiting proper amps to be provided to the CCU. The internal point type switches were not fully openning and therfore, with bumps or other changes in G-force would make contact causing the "clicking" noises? I don't know, but makes sense to me.
Did this last night. Won't know if it's the problem until I drive it a day or so. For 20 miles this A.M. there was no problem. Wait until it gets hot today at lunch.