Engine/Transmission (1998.5 - 2002) Fan Clutch Test

[BSnyder]

Can anyone tell me if there is a reliable way to determine if a fan clutch is good or bad on my 1999 ram 2500? My AC was just repaired and the tech told me the AC over-pressure relief valve sensed high head pressure and vented some 134 refrigerant and it could be a bad fan clutch. I told him that it was due to my error by attempting to temporarily repair my ac by adding coolant until the AC could be placed into the shop for proper repairs. I accidentally overcharged the system before he repaired the entire system. I read many old threads on the fan clutch and checked my fan clutch as described. Engine cold check for drag, it has drag good drag until it gets spun by hand for several revs and the viscus material inside the clutch moves then the fan clutch will spin somewhat freely. I have also noticed that at this point the assembly when stopped will have a slight movement if you hold a fan blade and push or pull gently other then what I've listed the fan seems to work normally and lock-up on pulls where my temp begins to rise and no signs of any leakage. My question is do I have a bad fan clutch or possibly just a bad high pressure relief valve on the AC compressor? If it is bad does anyone have correct part #'s and know where I'll get the best $.

Thanks for all your help!!!

P. S. when the AC was repaired the tech cleaned the radiator and evaporator of bugs and debris and cleaned the inside of the evaporator core for flow.

 

[WestTN]

If you can spin the fan a few times by hand and it frees up then it is definitely bad. After my truck has set for 15 minutes in 80 degree weather it takes several seconds at 1500 to 2000 rpm to cycle down. Until then the roar is quite respectable.

 

[Huff N Puff]

Once you have the exact amount refrigerant in your system A/c high side pressure is a very precise way of checking your fan clutch. The freon high side pressure and temperature is very sensitive to air flow,That being said,also make sure the radiator isn't plugged with debris from the blow by bottle,cause the fan clutch cant work if the heat cant get to the clutch to heat it up.