Over the weekend I installed a re-built Cruise Amp in my 83 300D. It seems to work pretty well other than a little bucking on slight downhill grades at 65 or so. My problem. Cruise engaged, turn on any button on the Climate Control and cruise shuts down. Lifting the lever (acc/set) it re-engages and seems OK. With cruise on, climate control on I can press other buttons on the climate control and all stays fine. Problem seems to only happen when cruise is on, climate is off then turned on. A/C is not functioning but compressor is OK, not engaged due to low refrigerant. Anyone have any idea what's going on here ???

Thanks Much.