Bad Fan, CCRM, or sensor?

[Deathacus]

Hey there! Ol' 94 MTX is running a bit hot.
Here's what's up. Temp doesn't appear to be super stable on the guage, but within a tolerance. When I am driving the highway, the needle stays around "M", or at most between "M" and "R". When I go through the city, or the convenience of the Sheetz drive-thru, she will climb, although some days seem better than others.
I was just checking the cooling fan. Let the car warm up in the driveway. Fan didn't turn on at all until the needle was almost at "O", wayyy too hot. couldn't tell ya if it was in low or high speed. However, when I turn on the A/C, fan spun up, no problem, when I turned the A/C off, the fan kept running just fine. Only when I shut the car off and back on again did the fan not want to spin anymore.
So I am at a loss. What do I check, what do I do? I have read CCRMs are common problems, but it seems like it shouldn't turn on with the A/C either. If it was the temp sensor, I would think the fan would still turn off after the A/C is shut off.

(Also, just how much should the temp drift normally? Like, how much should the needle move up and down?)

 

[Irish Pride]

I'll be very short here and not trying to be a smart-ass. If the temp needle is in the "Normal" range then it is not running hot. It is Normal to be within the Normal range. If the fan "is" coming on and the car isnt boiling over out the overflow then it is not running hot. Change the coolant sensor and see if that changes where the needle sits if you need a better peace of mind.

-Chad

 

[zoomlater]

My 94 MTX fan turns on at the O at idle

 

[Deathacus]

Thanks, but what about the A/C? I know the fan is supposed to come on with that, but if I turn the A/C back off, and the engine is still cold, shouldn't the fan turn back off as well?
I could have sworn I've read elsewhere in here that "O" is way too high and will warp heads, and should be closer to "M", and it does settle there for a little while, so I guess that's where the thermostat is set.
I mean sure, "NORMAL" meaning, well, normal makes sense, but I've never had a car where the needle ran more than halfway up, let alone 3/4.
I'm assuming the little fluctuations are just due to the true analog gauges. Gauges in my Kia and The Glorious Deathmobile are solid as a rock, but they might be dampened by the computer.
Not to doubt you two, yinz seem pretty knoledgeble, I've just never had a car that behaved like this.

 

[rubydist]

It is very typical on these engines for the temp gauge to swing quite a bit. Everything you are describing about your car is typical / normal for it.

 

[Deathacus]

Even the thing with running the A/C? If y'all say it's good, than I'll trust it should.
Kinda forgot I had a temp probe on my multimeter, so I'll run a sanity check against the specs in the repair book later. If it's all good then I guess she's a-go for Ponyville Ciderfest....unless something else breaks in the next month an a half

 

[Greg Corcoran]

So, also not to contradict anything here, but I had your symptoms on my '95 MTX. Was a bad ECT. After replacing CCRM a couple times, the X2J computer once, rigging up a relay and switch to force the fan on from inside the car, realized it was ECT sensor (with help from a former Ford factory trained mechanic I went to out of desperation). Near as I could tell ECT had drifted about 20-25 degrees colder than actual but the sender for the dash gauge remained accurate. So I would actually get to N and above in stop and go traffic.
The diagnostic test the mechanic performed? disconnected the ECT with the engine running, A/C off, and the fan came on immediately. According to him it's not that rare of an occurrence for the ECT to drift cold...

 

[BaySHO Performance]

My money is also on the ECT. Do a KOEO code check to see if you get a 117 or 118:

EEC Self Test Procedure - V6SHO

 

[Greg Corcoran]

My money is also on the ECT. Do a KOEO code check to see if you get a 117 or 118:

EEC Self Test Procedure - V6SHO

Nick, how far off does the ECT have to be to set a code? Mine never set a code which is why I didn't consider it as a potential source of the issue. But the Ford mechanic zeroed right in on it when I told him the issue and what I had done.

 

[BaySHO Performance]

ECT below minimum voltage (code 117) indicates 254F. Above maximum voltage (118) indicates -40F. Bottom line is if you get one of these codes, replace it:

ECT Sender (Duralast)

SU201

$25

Autozone

 

[tracy_s_1993_atx]

Many of the aftermarket ECT sensors are way off the Ford specifications. I tested 6 different sensors until I found one that matched the Ford specifications. I found that many of the aftermarket sensors read 10~15 degrees colder than the actual temerature.
I will see if I can find my data.
Michael

 

[tracy_s_1993_atx]

I found that the NAPA brand sensor was closer to the Ford Specification.