Cooling fan stays running?

metroplex · June 16, 2017, 10:51:38 PM

My 2014 SHO never had this issue before now. I had parked it for about 2 months while I drove my other car. I had flashed the SHO with a new tune and then had to revert it to the previous tune. Now I notice my cooling fans run all the time, even after a cold start. My A/C and defrost aren't running.

I don't see how something broke while the car was parked in the garage?? Any ideas?

TopherSho · June 16, 2017, 11:08:47 PM

How's the heat blow? Does it seem cold or drop super low ? Are you using a SCT tuner? What is the he coolant temp according to it ?

SHOdded · June 17, 2017, 02:19:31 AM

Have you flashed back to stock tune? That is what I would try first. But it is possible the fans need to be replaced.

ZSHO · June 17, 2017, 08:00:03 AM

It could be related to your Battery especially if it's been sitting for a while.
These cars have been known to act a bit wonky on a low battery,especially when loading a Tune.
Is it the original battery on there?
I would get a (Draw test) done and proceed from there!. Z

FoMoCoSHO · June 17, 2017, 09:28:05 AM

Since the car was stored, I'd check wiring for critter damage.

metroplex · June 19, 2017, 05:22:18 PM

I had a Pulsetech maintainer on the battery the whole time. I ran some diagnostics, reflashed to stock and back to the tune again (that worked fine before), and ran FORScan to monitor the A/C pressure. It was showing 107-108 psi without the engine running. Once the engine was on, the A/C was never on. It turns on when commanded and the pressure goes to about 111 psi. But the low speed fan keeps activating, even during a cold start with an ambient temperature of 75F!

Is the A/C pressure reading normal?

The Bronze · June 19, 2017, 05:59:43 PM

You could pull fuse 70 (15A) in the BJB. If it continues to run, then it indicates a stuck fan relay contact. If it shuts off, then it is being controlled by the PCM or the control wire is grounded.

My running pressure is ~230psi. AC enables PID = ON
Static pressure was 150psi.

On HPT there is a FAN DESIRED PID, but it doesn't work on mine, actually prevents a bunch of logging parameters from working. That would be helpful to see if it is commanded, or simply a stuck Relay

metroplex · June 19, 2017, 08:01:37 PM

I don't see the Fan PID in HPTuners. It doesn't have anything for the AC either. I'm using FORScan which has access to the HS CAN and MS CAN bus systems, so I was able to see A/C pressure, AC clutch command, Low Speed Fan, High Speed Fan, etc...

I'll give the fuse a try, the next thing I want to see is if the CHT is reading abnormally high. I recall the other day seeing my ECT at about 140-160F but the CHT was 197F. There's no ECT sensor, so the CHT data is used to infer ECT, but the fan settings are all based on ECT.

The Bronze · June 19, 2017, 08:42:12 PM

Fans are requested by Transmission Oil Temperature (TOT), Engine coolant temperature and A/C Pressure Looks like fan speed can then be determined by the fluid temp (and/or A/C pressure) vs. ambient temperature. I think any of these three sensors high (or possibly failing open) could enable the fans, although I haven't looked to see which fans are controlled by the A/C system.

HPT V3.6.5 has the AC channels (pressure, A/C request and clutch out failure(?) under systems_A/C.
You should see if you have success with the Fan (ratio) PID under systems_fans. Like I stated, it jams up my logging for most PIDS when I try to log that PID.

metroplex · June 19, 2017, 08:47:32 PM

I'm using 3.6.15 and don't see the Fans under Systems. I'll check out A/C.

My trans temp and ECT are all below the settings, so the fan shouldn't be running. The only thing that has me curious is why the A/C pressure reads over 100 psi without the engine running.

metroplex · June 19, 2017, 09:06:36 PM

I think the HVAC module or APIM or whatever controls the stupid touch panel buttons glitches out. I saw the Recirc flash for a split second during a cold start. My guess is that it kicks on the A/C compressor inadvertently and shuts it off, but it is enough to keep the fan running. This panel has given me issues with the Recirculate turning on/off by itself, or sometimes turning off the A/C by itself.

The Bronze · June 19, 2017, 09:22:19 PM

Quote from: metroplex on June 19, 2017, 08:47:32 PM
The only thing that has me curious is why the A/C pressure reads over 100 psi without the engine running.

I live in the frozen north, so A/C isn't my specialty, but if the running pressures operate around 50psi on the low side and 150 or so on the high side, the stabilized, rest pressure at 100psi seems reasonable.

The MINIMUM system pressure to engage the clutch is 42PSI.

The Bronze · June 22, 2017, 05:36:35 AM

What about fan minimum rpm. Not sure if that would override temperature when cold, but worth a look.

metroplex · June 22, 2017, 05:56:09 AM

I never changed it.

Does anyone else experience the same thing when they cold start without the AC running?

The Bronze · June 22, 2017, 06:23:22 AM

I checked mine tonight when I moved my car across the driveway to the shop. The fans shut down as i opened the car door to get out. It made me think of your issue, so I then restarted the car, deactivated the AC and checked it again. My fans were NOT running w/o the AC commanded on (cold).