Riceman

'06 A6 with forged 427, stock cooling system. Car overheated a few days ago, couldn't figure out why. Puked some coolant, so I refilled and changed the oil. Couldn't find any issues, so I drove it the next day. The AC suddenly cuts off, blower motor stays on but air is hot. I roll the windows down and the cooling fans aren't running. Car starts to get stupid hot, stupid fast. I coast it into a parking lot and let it sit to cool. Start it and drive it home a bit later, issue is gone again.

I'm kind of at a loss, I started it today and the AC and fans wont work at all. No codes, nothing. It has been running on the same tune and build since January with no issues.

What could cause the AC and fans to stop working (fans don't even work with AC off when engine is hot, yet they used to)?

racerrob333

First check the connections for the fans and then go from there u had motor work so u might have had a small leak in your AC system

CrazyChris

iTrader: (5)

Fans have their own fuse, make sure that isn't broke. Have seen a faulty radiator cap let air in the system which causes to overheat, but that wouldn't explain everything.

Riceman

Checked the J-fuse and it's fine. AC was working fine up until around last Wednesday when all this started. I installed the engine in January and the AC has worked perfect since then, but that's not to say it didn't fail. It still shouldn't cause the cooling fans to just stop working though. I checked the primary connection to them, it's fine. Have to trace it further back I guess.

Also, I thought a DTC/SES would be set if the PCM couldn't contact the fan controller module.

Riceman

Scanned with HPTuners, fans are commanded on when expected yet don't work. I tried manual controls, no dice. No pending or stored DTC's.

I let it idle up in the driveway from a cold start. Computer commands the fans on, nothing. Then, when the temps got to 228 or so, they came on. No change in the PID's, fans still commanded on just as they were before it started working.

No pending or stored DTC's, so it's like it can communicate with the fan controller. Can't be the fuse, it all works. When it wants to.

Todd157k

iTrader: (5)

pretty easy to track down.
disconnect the fans and hook up a meter or 12v light probe to the wiring going to the fans. Turn on the car. You don't have to wait until it warms up as the fans are commanded to come on immediately upon startup.
If you get 12v on the wiring, the fans are jammed or bad.
If you don't, start going backwards... to the fuses. Check for 12v at the fuse. If there's no 12v on either side of the fuse, the ecm isn't turning it on. If that's the case, you'll have to probe the ecm. I'll have to look up the pin for fans.

Riceman

If you could look up the pin-out for the '06 E38 (it's the 58x crank reluctor, so E38 is correct I believe) PCM I'd appreciate it. I'm going to have to go backwards. I know the fuse is good, it's a single 60A J-fuse, looks perfect and they work.. sometimes.

Riceman

Anybody have the pin-out schematic for the PCM in this thing? I need to start tracing the issue to and from the fan controller I guess...

one_and_only04

I hate to dig this thread up, but did you eventually work out what was wrong? I have a 2007 L98 VZ SS commodore and it's doing the exact same thing as yours was and it's driving me mad...

CySevans

When you checked the fan connector, did you actually unplug it? I had this exact problem but you couldn't tell there was a problem until I unplugged the connection and checked them. The C6Z is notorious for melting that connection, and if you're running a forged 427, I would wager you are having the same issue. The A/C will cut off when the coolant temp gets high to reduce load on the engine and help cool it back down. I fixed it on mine by removing the ground wire from the connector and direct soldering it.

See here:

http://forums.corvetteforum.com/c6-t...d-working.html