efan power is cycling on/off/on/off with the AC compressor

[Pete M]

isn't the efan supposed to just come on and stay on with the AC?  this truck is cycling with the compressor. 

 

 

[89 MJ]

I believe so, but just for fun, what do the engine temps look like when it’s switching on and off?

[eaglescout526]

Compressor is cycling? Thats a bigger issue than the fan staying on. Means your low on refrigerant. 

[Pete M]

engine temp on the REM (still have idiot lights) is around 190. 

 

maaaaaaaannnnn, I sure hope it's not leaking.   got it back from the shop just yesterday after they made it all worky-work.  the air is wicked cold.  (still need to diagnose why turning the setting to MAX makes the air switch to feet-only when bi-level functions normal)

[eaglescout526]

Orrrr Pete, the pressure switch is failing causing the system to cycle on and off like its doing. Thats another theory. But if its crazy cold, it could be charged correctly. Oh another thought that just occurred to me, our systems have a thermistor that cycles the compressor off to prevent the evap from freezing which is actually more of your issue now that I think about it. So if the thermistor triggers the entire AC system to switch off, why keep the fan running when the compressor isnt pumping any freon through the system. 

 

I dont have an Efan on the 2.5L to help figure this one out but thats just my idea on how its all operating. 

 

This being said, does the efan stay on the entire time until the thermistor reaches the temp to cycle the compressor on and off to prevent freezing? 

[Ωhm]

1 hour ago, Pete M said:

isn't the efan supposed to just come on and stay on with the AC?  this truck is cycling with the compressor.

 

When AC or MAX is selected using the dash panel, NO, EFAN does not stay ON but will cycle with the AC clutch.

[Pete M]

excellent.  

 

after noticing frost on the return line I realized I had the blower set on low.