climate control issue

[89Vette]

I would expect SUPPLY voltage to drop when the key is off. I would not expect the A/C control to drop voltage itself. The two other posters who've tried to help obviously believe the same...in providing suggestions where to look. The mere presence of a relay on that circuit implies [high amperage] voltage is supplied to the heater/controls when the car is turned on. That's why relays are used...to transfer the load "around" the ignition circuit.

Check other components on that circuit to see if they are still "live". How long has it been that way? Any chance it's been rewired incorrectly?

Did you try swapping relays (same ratings) to see what happened?

[maxprime]

I would expect SUPPLY voltage to drop when the key is off. I would not expect the A/C control to drop voltage itself. The two other posters who've tried to help obviously believe the same...in providing suggestions where to look. The mere presence of a relay on that circuit implies [high amperage] voltage is supplied to the heater/controls when the car is turned on. That's why relays are used...to transfer the load "around" the ignition circuit.

Check other components on that circuit to see if they are still "live". How long has it been that way? Any chance it's been rewired incorrectly?

Did you try swapping relays (same ratings) to see what happened?

I have checked the relays in the fuse block under the hood and they are working properly and I also even replaced them with new ones and no difference. I also installed a new ignition switch harness in the column, same issue. The wiring hasn't been touched. So, I know it is not wired wrong.
Is there any other relays that could be stuck and causing this and if so. Does anyone know where they could be located? I already have 90% of the dash removed.

[Y33TREKker]

I have checked the relays in the fuse block under the hood and they are working properly and I also even replaced them with new ones and no difference. I also installed a new ignition switch harness in the column, same issue. The wiring hasn't been touched. So, I know it is not wired wrong.
Is there any other relays that could be stuck and causing this and if so. Does anyone know where they could be located? I already have 90% of the dash removed.

Since you have better access to the components in the dash at the moment, checking the wiring to the Automatic Heater A/C Control Unit would likely be the best indicator at this point.

Find out which wires have constant voltage being supplied then we can narrow it down between which wires/inputs SHOULD actually have voltage being supplied with the ignition switch off and which wires/inputs are possibly getting a supply of voltage at the moment that SHOULD NOT.

If we know that and it's determined that there is voltage currently where there shouldn't be, maybe we can start tracing backwards from there and determine the source of the problem.