Compressor Running

[embedded rock]

So yesterday while driving a NF road with ambient temperature 68-72 degrees. Second and third gear speeds. 2WD.

I see these coolant and engine oil temps. The compressor turned on at one point. Really I'm not sure if it turned itself off.

Today, I start the Jeep for the first time today, and right away the compressor is running. No A/C light. I cycle the switch, but the compressor continues to run. A short mile and a hatto town, and I see the coolant temp rapidly increase to 190+ and cool to upper 180's just as quick. Engine oil temp seemed to increase quicker than normal for the beginning of this drive. It's maybe 90 degrees here.

So, why is the compressor running without command? Is this a response to something I'm not seeing/observing yet.

Yesterday, I made a point to detect coolant and burnt oil odors. Nothing. Coolant reservoir level looks like it has for 14k+ miles.

I need to make the 250 mile drive home tomorrow.

3.6l with automatic trans.

Tia.

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[jadmt]

I would say normal.

 

[NWJeepr]

IMO, this is normal. The HVAC has a humidity sensor and will run the AC compressor without turning on the button's light. Certain blend door modes will also activate the compressor automatically, like defrost or HVAC auto mode. If humidity was high, this could explain one scenario. If you don't want the compressor to run at all, turn the HVAC system completely off.

 

[embedded rock]

Yes, I would say the humidity is high here today.

 

[embedded rock]

I didn't experience this last year in Colorado or Utah when wheeling and that why yesterday and today something seemed wrong.

The humidity sensor and it's effect makes sense for what I'm experiencing now.

 

[TrailScooter]

I would say normal.

 

[embedded rock]

Last thought on the compressor running. I'm suspecting the HVAC system turned on the compressor for occupant comfort, and not for an engine heat scenario.

 

[HeN2O2]

The compressor runs in defrost mode. Check your climate control settings.

 

[Jeffy56]

Aha! Mine does this too occasionally. Duct setting to HI or HI/LO. Split A/C Temps 66 - 68. Outside temp 72-85. Humidity 15 - 35%. I feel the cooling from the vent. Frequently just after engine start-up. No indication that the A/C is on. If I switch to "Auto" for master control, wait a second, then turn that off, the A/C light to the right turns on. I then push the A/C button, the light goes out, and I'm back to ambient air in. No cooled air from the vent. I believe this is a firmware bug. Possibly a sensor issue, but this problem is only occasional. I'm not spending any money on it.

 

[NWJeepr]

Last thought on the compressor running. I'm suspecting the HVAC system turned on the compressor for occupant comfort, and not for an engine heat scenario.

Most likely. The cooling fans are electric and are activated by the ecu and don't need the AC compressor to run. Running the compressor generates heat in the engine bay via the condenser, but that is mitigated by activating the fan while the compressor is running, and also to help cool the condenser so the air reaching the cabin is cooler. Long way of saying if the engine needed to cool, just turning on the cooling fan would be a better way for it to cool itself.

 

[roaniecowpony]

Anytime the HVAC is in the "AUTO" setting, it can turn on the AC compressor as the sensors meet the programmed criteria. Usually, that's the interior temp sensor. But, if the HVAC was in the "OFF" setting and the compressor engaged, I'm at a loss.

 

[Jeffy56]

Additional info: Cabin filter is changed minimum of once a year and was done earlier this year.

 

[embedded rock]

Anytime the HVAC is in the "AUTO" setting, it can turn on the AC compressor as the sensors meet the programmed criteria. Usually, that's the interior temp sensor. But, if the HVAC was in the "OFF" setting and the compressor engaged, I'm at a loss.

Thanks, good to know. Mine is set to AUTO.

 

[embedded rock]

Most likely. The cooling fans are electric and are activated by the ecu and don't need the AC compressor to run. Running the compressor generates heat in the engine bay via the condenser, but that is mitigated by activating the fan while the compressor is running, and also to help cool the condenser so the air reaching the cabin is cooler. Long way of saying if the engine needed to cool, just turning on the cooling fan would be a better way for it to cool itself.

Sounds like (from other readings in this forum too--especially the aftermarket engine cooling fan controller, that the ECU is late (higher coolant temps) to turn on the electric fan; however, the HVAC can get the coolant fan turned on at a lower temp. Sound right?

 

[Upnarms]

My ac compressor runs whenever I'm in park no matter what the setting. Had done this since new. Jeep claimed unable to replicate, but it is literally every time its in park. Also my climate control is finicky. It blows the coldest air no matter the temp setting until you reach high 70s or 80. Then if you back it down it will adjust. Same with heat but opposite. I just gave up on it and go through the hassle since there isn't much i can do.

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