Excuse me for bringing this old thread as I am facing the same issue. No blower at any setting, but condensers and compressor all work fine and I can get cold air if I set to outside air inlet and drive at high speed.
My blower motor does not blow. I have done the following checks:
- checked both fuses while removed also by continuty, continuty ok
- blu/wht to ground voltage with igintion on, voltage found
- ylw/blk to ground voltage with ignition on, voltage found
- powered the blower relay and checked continuty, continuty ok
- blu/red to ground voltage with ignition on, voltage found OK - preceding was done correctly and confirms that the blower relay and power supply is OK
- next step in manual says to give power from battery to blu/red ground to blu/blk, which does not make sense because the blower 2p is disconnected, however I did as mentioned but does not run blower. Instead I tried to give power to the blower wires connector side and the blower ran succesfully at full speed. Good, confirms that your blower motor is not dead.
-next step says to jumper the blu/blk wire to ground but blower motor does not run.
-i tried next step jumper blu/blk to blk wire but blower still does not run
-measured ylw/blk to ground voltage, found ok
-removed ccu and jumpered orn/wht to ground but still blower does not run
Now to things which I tried and not mentioned in service manual:
- battery to fuse 30A voltage ok, fuse to ground voltage ok, blu/wht coming from fuse box at relay connector voltage ok
- blu/red from relay to 2p connector continuty ok
- ylw/blk to ground voltage ok. ylw/blk continuty from relay connector to ccu 30p ok for both relays connectors
- orn/wht continuty from relay connector to ccu 30p ok also
- blk to ground for both relays connectors found ok
- light grn/blk continuty from 3p connector to ccu 30p ok also
- blk pins 24 & 25 of ccu 30p to ground found ok.
- continuty of blu/blk wire from any point to another no contintuy was found. this one of things I suspect the most, maybe wire damage. I checked blu/blk from blower 2p connector to hi relay connector no continuty, and to 3p connector no continuty, and to ccu 30p no continuty also.
I suspect that you have discovered the problem. If you do a continuity check from the blk/blu wire on the wire harness plug on the blower motor to the blk/blu wire on the wire harness plug on the blower high relay and find an open circuit, that guarantees non operation of the blower motor. See the attached wiring diagram. If that blk/blu wire from the blower motor to high relay is open circuit then there is no ground connection for the blower motor resulting in non operation. The first place I would check is the condition of the wiring where it enters the wire harness plug on the blower motor and the wire harness plug on the blower high relay. Look for broken wiring. Without knowing your model year, I don't know how the wire harness is set up. If you go to the electrical portion of the service manual, front compartment wire harness, it will show you the routing of the wire harness form the blower motor plug (C219) to the blower high relay plug (C232). You should be able to trace the harness and look for visible damage once you know the wire harness route from the blower to the high relay. If damage is not obvious, it pretty much means unwrapping the harness. Before you do that, run an external jumper from the back side of the blk/blu wire on the blower high relay plug to the back side of the blk/blu wire on the blower plug. Do this with everything plugged together and then try powering up the ignition and running the blower. This will confirm that the problem is a broken wire between the high relay and the blower. You don't want to go cutting open the harness if the problem is somewhere else. Before you do the jumper test, read my comment below about testing the wiring down to the power transistor.
- i tried replacing and swapping the relays with others that i know they work like horn and still no luck.
- i have removed the blower housing completly from the car and disassembled the motor and cleaned it and assembled it again, and gave it battery power and it ran and spinned in front of my eyes.
- yesterday i tried a ccu from another NSX of a good friend, his AC works all fine, but still no luck with my blower.
I need help, what other diagnoses I can do?
Does any one know how the blu/blk is routed in the car? From the ccu 30p goes to where then where before it crosses the wall, and after the wall it goes to where and where and where and where before it reaches finally to the blower connector? I have the diagram in the service manual but that does not help to tell how it is physically routed? I suspect it might be torn or damaged or open somewhere.
It looks like the connection from the blower to the high relay and power transistor is all internal to the front wiring harness. However, it does not look like the front wiring harness goes directly to the CCU. It looks like the front wiring harness connects to the floor wiring harness and perhaps the floor wiring harness connects to the CCU. Normally car makers do not put taps in the middle of the wiring harness. Check the back of the plugs on the blower and the high relay. If one of those plugs has two blk/blu wires, the safe bet is that one of those wires goes to the CCU. It is also possible that the blk/ blu wire from the blower goes to the power transistor and then from the power transistor to the high relay so pull the connector for the power transistor and check the condition of the blk/blu wiring there. Also, do a continuity check from the blk / blu wire on the power transistor to the blk/ blu wire on the blower motor and the blk/blu wire on the high relay connector. That may help you narrow down where the bad connection is.
The common wiring point failure is the plug or where wire enters the plug. Wiring failure within the harness is pretty rare unless something is rubbing the harness or has hit the harness.
But if it is not the blu/blk wire then what could it be?
Appreciate if anyone can help please?
