Originally Posted by LakewoodBrew
from your description i can't tell for sure but it sounds like you are expecting the relay output to produce a voltage output.... not going to happen. The relay outputs are just switches. you need to provide a source and load in series with the relay terminals to have an effect.
Sorry is my terminology isn't perfect. My experience with electronics is limited.
I'm not sure exactly what you're suggesting. You seem to know more about this than I do, so perhaps if I provided more information on the way it's wired, you could help direct me.
Currently, I have it wired the same way as in this diagram from the eBay Aquarium Temp Controller thread:
I do have constant power running into ports 5 and 7, with the outputs (6 and 8 respectively) going to electrical outlets that are not connected together. In an attempt to isolate the problem, I have removed the outlet and I'm checking the wiring with a very simple illuminating voltage tester. When it makes a connection and power flows through that connection, it lights up.
In my testing, for example, when the heat turns on, the light for heat on the display is a solid dot. When connecting the voltage tester to the screws on the unit, connecting pins 2 and 5 lights up but connecting pins 2 and 6 do not. Also, there are people talking about the unit audibly clicking when either heat or cooling turns on, but I hear no noise when it engages either function.
Here's the picture of the transformer inside the unit. Perhaps this would help?