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Running Hotter with A/C #4503649
08/31/17 06:06 PM
08/31/17 06:06 PM
Joined: Feb 2013
Posts: 10,703
Phoenix, AZ
Nick1994 Offline OP
Nick1994  Offline OP
Joined: Feb 2013
Posts: 10,703
Phoenix, AZ
I've done more testing in this now with my Jeep. I toughed it out and drove in traffic (110 degrees out) and WITH A/C it ran at around 220-222. Once I turn OFF the A/C it goes down to 210-212 within a couple minutes. I did this multiple times driving to work today and then with the A/C on I was stopped at a light on the freeway off ramp and it jumped closer to 230. Turning on the heat and a/c off it went down to 210 after a minute or two.

All cooling components have been replaced.

What causes this? A/C blows pretty cold, compressor makes a little bit of noise but not bad. Compressor doesn't seem like it's extremely hot either. Condenser is clean.

Thanks


2015 Hyundai Sonata 2.4L 84k Mobil 1 AFE 0w30 & OEM
2000 Toyota Camry 2.2L 230k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 147k Mobil 1 HM 10w40 & Fram Ultra
Re: Running Hotter with A/C [Re: Nick1994] #4503664
08/31/17 06:16 PM
08/31/17 06:16 PM
Joined: Jul 2009
Posts: 599
texas
danez_yoda Offline
danez_yoda  Offline
Joined: Jul 2009
Posts: 599
texas
Did it start doing that or has it done it all along?

If its always done it it could be the temperature sensors proximity to the AC compressor. Compressor gets hot and warms up the temp sensor.

On a 1996 the fluid temp should be controlled with a mechanical thermostat so the engine temperature should not be load dependent.

Also check the electric fan speed through the radiator when the AC is on vs off. It could be that it is slowing down under the electrical load of the AC.

Re: Running Hotter with A/C [Re: Nick1994] #4503669
08/31/17 06:19 PM
08/31/17 06:19 PM
Joined: Aug 2008
Posts: 3,161
USA
Reddy45 Online shocked
Reddy45  Online Shocked
Joined: Aug 2008
Posts: 3,161
USA
Maybe I'm not understanding this fully, but that seems quite reasonable. The AC is moving heat that is inside the cab, to the outside -- at the condenser. All of that heat ends up near the engine (which is also under additional load from the compressor), so a small rise in temps seems OK.

Re: Running Hotter with A/C [Re: Nick1994] #4503676
08/31/17 06:22 PM
08/31/17 06:22 PM
Joined: Dec 2006
Posts: 7,654
Toronto, Canada
KrisZ Offline
KrisZ  Offline
Joined: Dec 2006
Posts: 7,654
Toronto, Canada
The condenser is in front of the radiator, so when you turn on the AC, the hot air coming off of the condenser goes through the radiator next. In effect it reduces the heat removal capacity from the radiator a little bit, hence the increase in the temperature.


2015 Dodge Grand Caravan-27k miles.
2006 Mazda 3-163k miles
Re: Running Hotter with A/C [Re: danez_yoda] #4503685
08/31/17 06:33 PM
08/31/17 06:33 PM
Joined: Feb 2013
Posts: 10,703
Phoenix, AZ
Nick1994 Offline OP
Nick1994  Offline OP
Joined: Feb 2013
Posts: 10,703
Phoenix, AZ
Originally Posted By: danez_yoda
Did it start doing that or has it done it all along?

If its always done it it could be the temperature sensors proximity to the AC compressor. Compressor gets hot and warms up the temp sensor.

On a 1996 the fluid temp should be controlled with a mechanical thermostat so the engine temperature should not be load dependent.

Also check the electric fan speed through the radiator when the AC is on vs off. It could be that it is slowing down under the electrical load of the AC.
It's been doing it for a while.

It has 2 temperature sensors. 1 at the front of the engine, not too close to the compressor in the thermostat housing. This gives the reading to the computer.

It has another at the back of the head which gives the temperature to my mechanical gauge on the dash, this is a real gauge not the cluster gauge.

I've replaced the sensors and verified with a scan tool and IR temp thermometer that the temperatures are correct.


2015 Hyundai Sonata 2.4L 84k Mobil 1 AFE 0w30 & OEM
2000 Toyota Camry 2.2L 230k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 147k Mobil 1 HM 10w40 & Fram Ultra
Re: Running Hotter with A/C [Re: Nick1994] #4503686
08/31/17 06:35 PM
08/31/17 06:35 PM
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Merkava_4 Offline
Merkava_4  Offline
Joined: Jan 2007
Posts: 17,501
Clovis, CA
It's that clutch fan that's doing it. With electric fans, they run all the time with the A/C is on.

Re: Running Hotter with A/C [Re: Merkava_4] #4503704
08/31/17 06:47 PM
08/31/17 06:47 PM
Joined: Feb 2013
Posts: 10,703
Phoenix, AZ
Nick1994 Offline OP
Nick1994  Offline OP
Joined: Feb 2013
Posts: 10,703
Phoenix, AZ
Originally Posted By: Merkava_4
It's that clutch fan that's doing it. With electric fans, they run all the time with the A/C is on.
It also has an electric fan


2015 Hyundai Sonata 2.4L 84k Mobil 1 AFE 0w30 & OEM
2000 Toyota Camry 2.2L 230k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 147k Mobil 1 HM 10w40 & Fram Ultra
Re: Running Hotter with A/C [Re: KrisZ] #4503712
08/31/17 06:56 PM
08/31/17 06:56 PM
Joined: Jan 2009
Posts: 6,200
New England
gathermewool Offline
gathermewool  Offline
Joined: Jan 2009
Posts: 6,200
New England
Originally Posted By: KrisZ
The condenser is in front of the radiator, so when you turn on the AC, the hot air coming off of the condenser goes through the radiator next. In effect it reduces the heat removal capacity from the radiator a little bit, hence the increase in the temperature.


+1

The oil in the Forester XT is coolant-cooled. The multi-function display on our Forester XT shows oil temperature. The oil temperature, like the coolant, rises when the A/C is on, even while at highway speeds.


'14 Forester XT FA20DIT (Cobb Stage 1)
Edge 0W-40 + FU filter
'15 Legacy FB25 (OEM Stage, uh, neg. 7?)
Edge 0W-20 + FU filter
Re: Running Hotter with A/C [Re: Nick1994] #4503715
08/31/17 06:59 PM
08/31/17 06:59 PM
Joined: Jan 2011
Posts: 2,943
PV Az
AZjeff Offline
AZjeff  Offline
Joined: Jan 2011
Posts: 2,943
PV Az
So in 110 ambient you see temps bump up 10 degrees with the AC on.

What is your thermostat? Any chance to drop it 10 degrees and give yourself a little room?

This could be a case where a bottle of Redline Waterwetter could do some good.

The Jeep is 21 years old, cut it some slack and roll the windows down! You're a native, 110 is just getting warm. wink


86 Samurai 1.3 leftovers
14 RAV4 2.5 5W-20 PP
16 Silverado 1500 4.3, DI, AFM 5W-30 PP

The most important thing to do in your life is to not interfere with someone else's life. - Frank Zappa

Re: Running Hotter with A/C [Re: Nick1994] #4503731
08/31/17 07:15 PM
08/31/17 07:15 PM
Joined: Jan 2013
Posts: 1,842
Texas
WyrTwister Offline
WyrTwister  Offline
Joined: Jan 2013
Posts: 1,842
Texas
Is the gauge showing HOT ?

Have it boiled out any coolant ?

Here is my take on this . As long as the coolant is at least 50% - 50% and is circulating properly , you will not damage the engine if it has not boiled off any coolant .

Am I right ? Wrong ?

Best of luck , :-)


Wyr
God bless
Re: Running Hotter with A/C [Re: KrisZ] #4503740
08/31/17 07:19 PM
08/31/17 07:19 PM
Joined: Oct 2005
Posts: 7,094
Colorado
Kuato Offline
Kuato  Offline
Joined: Oct 2005
Posts: 7,094
Colorado
Originally Posted By: Reddy45
... The AC is moving heat that is inside the cab, to the outside -- at the condenser. All of that heat ends up near the engine (which is also under additional load from the compressor), so a small rise in temps seems OK.


Originally Posted By: KrisZ
The condenser is in front of the radiator, so when you turn on the AC, the hot air coming off of the condenser goes through the radiator next. In effect it reduces the heat removal capacity from the radiator a little bit, hence the increase in the temperature.


These easily account for the few degree change you're seeing. Drive on.


Thick vs Thin test: 15k / 43k miles complete
Re: Running Hotter with A/C [Re: WyrTwister] #4503745
08/31/17 07:23 PM
08/31/17 07:23 PM
Joined: May 2006
Posts: 2,206
Lakeside CA
another Todd Offline
another Todd  Offline
Joined: May 2006
Posts: 2,206
Lakeside CA
Originally Posted By: WyrTwister
Is the gauge showing HOT ?

Have it boiled out any coolant ?

Here is my take on this . As long as the coolant is at least 50% - 50% and is circulating properly , you will not damage the engine if it has not boiled off any coolant .

Am I right ?


In terms of boiling off coolant, the radiator pressure cap is much more important than coolant/antifreeze. Roughly, for each pound of pressure the system holds, the boiling point goes up 3 degrees. So a 15 lb. cap in good condition won't allow water to boil until roughly 255 degrees if no leaks in the system.

In terms of doing engine damage from overheating without coolant boiling over, yes it is possible.


2015 Ford F250 Diesel Crew Cab FX4
2017 Ford Escape 2.0
2002 GMC Yukon
2015 Hyundai Accent
2008 Yamaha Rhino 700 FI
Re: Running Hotter with A/C [Re: Nick1994] #4503761
08/31/17 07:37 PM
08/31/17 07:37 PM
Joined: Sep 2014
Posts: 1,446
Toronto Canada
WobblyElvis Offline
WobblyElvis  Offline
Joined: Sep 2014
Posts: 1,446
Toronto Canada
There is nothing wrong with the Jeep. Under more load it runs hotter.

Re: Running Hotter with A/C [Re: Nick1994] #4503797
08/31/17 07:59 PM
08/31/17 07:59 PM
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Merkava_4 Offline
Merkava_4  Offline
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Originally Posted By: Nick1994
It also has an electric fan


You need two large electric fans with two speeds. Low speed comes on at 216F and high speed comes on at 221F. With A/C on, it automatically defaults to high speed.

I drive around town with the A/C on and water temp is at 176F. Ambient over 100F.

Re: Running Hotter with A/C [Re: Nick1994] #4503809
08/31/17 08:06 PM
08/31/17 08:06 PM
Joined: Feb 2013
Posts: 10,703
Phoenix, AZ
Nick1994 Offline OP
Nick1994  Offline OP
Joined: Feb 2013
Posts: 10,703
Phoenix, AZ
So 230 degree spikes are no issue?

I have major concerns of off-roading in the desert and overheating in the middle of nowhere. Or pulling my small trailer in the mountains and getting too hot.

For comparison a customer of my mechanic's has the identical Jeep, same year, even same color! His is almost always 195 degrees, same gauge.


2015 Hyundai Sonata 2.4L 84k Mobil 1 AFE 0w30 & OEM
2000 Toyota Camry 2.2L 230k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 147k Mobil 1 HM 10w40 & Fram Ultra
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