hvac no power

2000 bravada, no power to rear def., a/c, or rec.,or blower motor. a/c comp.is on cant turn off. checked all fuses w/ voltmeter ...good, ran a temp. hot line to blower motor to test ...works fine. thought maybe relay but cant locate to test before i buy a climate control cluster . looks like it would be expensive. any help locating the relay or any other possible causes would be great.

Because the rear defroster/non AC, is not working, I'd suspect a module. I don't have a 2000 manual. You might try reposting this in the Problem Diagnosis/Blazer section.

You might try to "reboot" the module by disconnecting the negative battery cable for 20 minutes then reconnect and check your AC system.