A/C and cooling fan high speed

[86T-Top]

Hi,

I seem to be having a little overheating issue with the car when I run my A/C on a hot day. So after doing some research I am leaning towards the CCRM is not getting a signal on pin #17 when the A/C is turned on. I went out to the car and with the car running and the A/C running the high speed cooling fan was not on, although the low speed fan will eventually turn on. Additionally there was no continuity to ground when I back probed pin #17 on the CCRM connector. So my question is as follows: Is the high speed portion of the cooling fan supposed to come on as soon as the A/C is turned on, or does it only turn on when the Freon reaches a certain pressure, or coolant reaches a certain temp?

I know that my high speed circuit does work, because it comes on when I run a KOEO diagnostic, and it will come on when the motor gets very hot without the A/C on, but I have never seen it on when I run the A/C no matter what temp I am running at.

So do I actually have a fan issue since the high speed does not turn on as soon as the A/C compressor engages, or is the fan operating as it should?

Thanks,

Mario

 

[cjones]

from what i see, the AC High Pressure Cutout/Fan swt controls the highspeed fan.

when the AC pressure reaches 325psi the swt closes and the highspeed fan comes on. once the pressure drops to 275psi the swt opens the fan turns off after 20 seconds.

it appears that when the Pk/LB wire at the AC High Pressure Cutout/Fan swt is grounded through that swt (to the BK wire), it tells the computer to turn on the highspeed fan. the PK/LB wire goes to Pin 42 of the ECM.