Right on! As Sherlock Holmes once put it, when you have eliminated all other possibilities, the one that is left, no matter how unlikely, is the correct solution.
Because I don't have a spare ECR module, I simply bypassed it. Voila! Air blows cold and compressor can be turned on and off from the ccu. All I lack is the auto climate control feature. But compared to sweltering in the heat, this is a small sacrifice.
To get the aux fan I will change out the pressure switch in the receiver-dryer. Since the ice cube relay is working, and the fan runs when the pigtail leads are jumpered, that remains as the only possibility.
I thank you for your quick comeback and solution to my problem.
Stage Wizards Lighting and sound designer
1981 SD 328,000
1985 300TD, 266,000
1984 300 TD, 267,000