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Lost my power to my heater a/c today bench tested the relay and blower motor both are working fuse is good power on both sides but no power at the fan speed switch is there something else I'm missing any information or suggestions would be a big help.
It's an 83 oldsmobile ninety eight regency the fuse is good on both sides but no power at the fan speed switch no melted wires it was working then stopped and like I said previously I bench tested the relay and blower motor and they work fine and there is no power going to them as well
The 1977-90 B/C body cars have the same connector and same problem as the G-body cars. The HVAC harness mates to the engine harness at a four-pin square connector on the passenger side of the engine compartment, near the distributor. That four pin connector actually has only three wires in it. One is a heavy-gauge red wire that is the power source for the HVAC system. This terminal is undersized for the current and since it is not sealed, it gets wet and corrodes in the engine compartment. This causes resistance that causes heat that eventually melts the connector body and prevents the system from getting powered. I've owned five of these B-body cars and all of them have had this problem at one time or another.
Well I found the plastic connector by the distributor I have power in the connector but still none at the fan speed switch and no power out of the plastic connector
When you tested for power, did you reconnect the two and back probe the connector to the HVAC to verify power on that red wire AFTER the connector? If so, then you need to continue tracing the circuit back under the dash until you find where the power stops. This isn't going to be diagnosed by remote control, only brute force tracing of the circuit.
Well done Joe and others guiding OP to a known design flaw in the system, you’ve save OP a lot of time.
OP - as you trace the break or short; To keep colors straight, you can use lacquer thinner to clean the wires. If you’re not color blind like me, tracing will be easier looking for consistent colored wires. Also, as you trouble shoot electricals, look for melted plastic shells first, then breaks in wires where they move (like in door jambs), then shorts, then lack of ground (if your car has lots of plastic).
You are well advised to clean (really clean - like with a dremel to remove corrosion/carbon scoring) any metal male or female contacts inside melted plastic shells. Look extra hard at circuits you know carry high amperage (like the heater/A/C motor inbound line). If the high amperage connections get dirty ( which they do over 50 years..) they can get hot & melt. If you see a melt, it means you have some remediation to do.
Looking at those 80’s harnesses and emissions equipment makes me love the simplicity of my ‘66’s all the more. GM had like 3 electrical tricks in the ‘60’s - relays, potentiometers and brass contacts. The older I get, the more I revere simplicity.
OP - good luck, you’ll find the error along the way. Be patient and do the work when you’re excited to do it.
