Of course you could swap identical relays to see if problems move with a suspected defective relay.
We well use the lo speed fan relay in the PDC - same info. applies to all of the 5-pin relays.
Overview of PDC:
Zoomed in on the PDC overview to see the pinouts on the lo speed fan relay socket:
Schematic of the lo speed fan relay so you can see functionality (I added the 'E' label, as it had been omitted from that schematic because it is not used in this circuit):
The pins are also numberd - you may see the numbering on the relay itself.
Here are pin letters, numbers, and function:
A = 86 = coil wire
B = 30 = contact common
C = 85 = 2nd coil wire
D = 87 = contact normally open
E = 87A = contact normally closed
You should hear/feel relay click when +12 volts is applied and removed from across the coil (A and C)
With relay not energized, ohmmeter should show 'open' from B to D, should show a fraction of an ohm from B to E.
With 12 volts applied across coil (A and C), ohmmeter should show 'open' from B to E, should show a fraction of an ohm from B to D.