a/c causing error codes po 480

[slip60]

Just charged and used my new Classic air system and I am getting error code po 480, fan relay problem. I have an ls3 that has been tuned and programmed prior to adding a/c. Not sure why fan error code is coming on because both fans are working when a/c is turned on. Fans also work as needed when engine temps rise without incident. Any help would be appreciated..running painless relay fan kit 30117 and ford Windstar dual fans ...thanks all for ur help

[hotrodneb]

Working on the same sorta problem myself. Are you running a single fan? (I am)

I ran the 2 wires from PCM to a single pole for the fan relay. Initially I set a P0481 (fan2) I learned that the PCM needs to see a certain resistance over the circuit, otherwise it sets a code. I added an 8 ohm resistor to each lead (fan 1&2). The relay should be about 20 ohm. So when in Fan 1 I show the PCM 28 ohm and when both are on the PCM will be seeing 18 ohm per lead. So far no code. After I did this I read somewhere that 47 ohm was right, so I have a couple 47 ohm .5-1.0 watt resistors on the way.

[MonzaRacer]

Its got several determining factors. Check obd-codes.com/p0480
This has several setting parameters, and what can also cause this code.
I prefer using GM relays anyway. Personally I like the oval version but looking up appropriate relay for the similar year as your PCM/program and tie it in. See GM has tied ac request into the computer. Then the PCM engages ac relay. This way the computwer also knows when to increase IAC control to raise idle speed to compensate.
Who reprogrammed your PCM either failed to allow for separate ac control or you need to integrate your ac control signals into the PCM wiring.
Allowing ecm to know when your requesting ac might avoid setting code or letting ac control come from PCM after being"turned on" by ac controls.

[slip60]

Thanks to both for trying to help and your advice..will post when I remedy problem