my cooling fan is not coming on and its letting my a/c head pressure skyrocket to high, the fan cycles normal to cool radiator, just not coming on in time to lower my a/c head pressure,... any suggestions??? what controles fan during ac operation thanks..

 

All i know is that when you set the control to max ac it works through that switch to turn it on so i would start there. It has to have a wire from there to the fan relay thats mounted between the battery and radiator.

 

Check my sig line.

What is your high side A/C pressure at? If you're low on refrigerant, the high side won't get high enough and the fan will stay off. But I'd check with some pressure gauges first.

 

on the low side its going over 80 and compressor starts vibrating and i cut it off the high side starts pegging out to, i can manully ground the fan relay and fan comes on and pressures go down to normal and a/c cools , just dont know what should activate the fan relay when a/c is on and pressures get high enough that fan should come on??? any help is good.