Have lost all fan speed control in both hot/A/C settings. Resistor pack checks out okay. Fan runs when voltage applied direct to it. Have +12v into r-pack. Fuse (inside) okay. The fan speed is controlled by adding resistance between Fan & ground. Thermal cutout part on R-pack okay. How do I test out the relay (in engine compartment), and could that even be the prob? Will look at dash switch next. Any suggestions? Anyone have a schematic for this?
You will need to provide a little better description of the problem. Does the fan run at all when you select a fan speed? Will it run at the highest fan speed?
As for checking the relay, pull the relay. On the side, there may be a diagram showing which terminals go to the coil and which go to the contacts. Take a short piece of wire and short out the two terminals in the relay socket that correspond to the terminals.
If the fan works, then you need to check that the coil is getting the 12v on one coil terminal in the socket and ground on the other when the fan is turned on. If you have 12v on one coil terminal, then you have to chase the wire from the ground terminal to the switch.
If the fan does not work, you need to determine which contact terminal has 12v on it and check the wiring from the other contact terminal to the resistor pack.
The easiest way to check a relay is to substitute one of the others. Usually they all have the same part numbers so just swap it. Jump across the switch to see if its the switch.