djb383

If there is no a/c refrigerant pressure (compressor not running) the ECU will turn the radiator efan on when engine coolant reaches 223F.

OffRoadNewb

Hm... I'm not sure I could get it up to that temp right now. I'm running a 185 tstat and even when I'm wheeling in the summer time with the ac on it hangs out around 225... If it wasn't FL and for the hot summers I would run a hotter tstat.

OffRoadNewb

I'll try to get creative with getting the temp up when I get home from work and report back with what I find.

djb383

I presume u r going by the dash temp gauge......if it's accurate, probably not, u should hear the radiator efan at 225F, it's very noticable when on (unless u have loud exhaust).

If all components of your cooling system r in 100% top notch condition, u'll never the rad efan this time of year (unless refrigerant pressure reaches X psi and that ain't going to happen if the compressor is not engaged).

OffRoadNewb

Yea I have noticed it before... hard to miss when it comes on. I actually replaced that fan last summer as the old one cracked and would wobble, which was pretty annoying... so I put in a new fan. I'm going by dash but have had a scanner on it and compared temps to the dash to have an idea how much it is off.

djb383

Mathematically, this is how the dash gauge breaks down.

djb383

I forget, u r in Florida, u may hear the rad efan this time of year. LOL

OffRoadNewb

Ha ha. Not today... its "cold" (ha ha) and rainy. I'll have to use some blankets to block off air flow and maybe restrict a radiator hose a little.

drhoward1988

Block off the radiator yes...but don't restrict flow of a hose. Puts more stress on seals and your water pump from the building back pressure.

djb383

We run a 180F Stant SuperStat t-stat year round......where did u find a 185F stat/what brand?

OffRoadNewb

That may be it... I know it was in that range of temp. Def cooler than the stock temp.

OffRoadNewb

Alrighty, will do.

OffRoadNewb

Alright... I REALLY don't want to do that again... really.

So I got the air flow blocked off... got the temp to rise up slowly but surely (on the dash gauge). Got to the mark after the 210 mark... fan wouldn't come on. It really didn't want to heat up past that mark just by sitting, so I put it in drive and just a little over 1k rpms with my foot on the brake, about 30 sec in the needle jumped to the red and the "check gauges" light came on... scared the **** out of me so I immediately shut it off, ripped everything off, opened the hood and stuck a big fan out in front of the jeep to cool it off. Started it back up a few minutes later and all was ok.

During the ordeal, the electric ac fan on the radiator never turned on once. I also while I was at it hooked up the fan directly to 12v just to make sure it still worked, and it does.

So there ya go... So tell me, what did I find out by almost overheating my Jeep? lol

djb383

U may have a bad coolant temp sensor. I would think the rad efan would be on when coolant temp was between the 222.5F and 235F marks.

Do u still have access to the scanner so u can verify coolant temp?

drhoward1988

Does the efan on the coolant side work off a relay? If your willing to try again hook your meter up to the leads at the fan and see if it ever reads power.