Overheating, Only when air conditioning is on

jr4jc · 07-15-2012, 05:55 PM

2005 sti stage 3 with new water pump. have mishimoto racing radiator
and;

Overheating, Only when air conditioning is on.
fans are coming on correctly.
coolant; overflow was empty, upper radiator was full
filled overflow, ran it for 10 minutes with heater on, and it took up half the over flow. still running warm to next line up, not in the red
so next filled overflow again and ran it for 25 minutes with radiatior cap off, and heater on.
didn't take up anymore, didn't see level drop any.
overheating is taking place with easy driving, highway or local doesn't matter, but having the air conditioner on does.

when it overheats it just goes up to the next line, never into the red
when it does if i turn off the air, it cools right back to normal.
could the compressor pull enough to make the water pump belt not turn the water pump correctly.

i have a thermastat and am ready to change it but i can't see how that be the problem???

HELP!!

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jr4jc · 07-15-2012, 11:44 PM

i think its air in the cooling system, after my original post i spent about an hour warming engine and massaging air out of the upper pipe, refilling, letting it cool and warming back up. got a lot of air out of the system.

jr4jc · 07-21-2012, 11:49 PM

OK anybody that could of figured this one out deserves a prize.
So i take the car back to where I had freon put in the cooling system and WE start looking at everything. no air to speak of in the cooling system, fans checked out, nothing making sense, we get an infared gun and start measuring temps. find a 250 ish somewhere behind the belts and the fans....cant quite figure out where its coming from cause of moving belts and moving fan....raise the gun a little and.......its the alternator. 310 degrees at 2000 rpm.
we disconect and drive it 10 miles with the air on, NO overheating.
wow how strange, got a new one from subaru, holy crap this thing better mow the lawn and walk the dog...but no more overheating.

rymaggi · 07-22-2012, 12:16 AM

I'm having the same problem. Fans come on correctly. But when I'm stuck in traffic, car starts over heating, but when I start driving again it starts cooling down.

motohippy · 07-23-2012, 08:55 AM

Quote:

Originally Posted by rymaggi

I'm having the same problem. Fans come on correctly. But when I'm stuck in traffic, car starts over heating, but when I start driving again it starts cooling down.

Bad thermostat, maybe??

rymaggi · 07-23-2012, 04:56 PM

Quote:

Originally Posted by motohippy

Bad thermostat, maybe??

Why would a bad thermostat do that?

treedspeed · 07-23-2012, 04:57 PM

i'm not sure it would.
how about fan switch? though not sure if that would also create the issue op described.

SubyMass · 07-24-2012, 03:28 PM

Doesn't sound like this is your problem but maybe it leads you in the right direction. If a radiator is getting clogged and doesn't let enough flow through it, having the extra thermal load (or increased air input temp) from the AC condenser can make the car overheat.

Also a broken thermostat that's open (or if the thermostat is missing) will allow for too high of a fluid flow through the block limiting how much heat the coolant can absorb and transfer to the radiator.

Hope it helps, good luck!

Zippo029 · 07-25-2012, 04:30 PM

Quote:

Originally Posted by SubyMass

Also a broken thermostat that's open (or if the thermostat is missing) will allow for too high of a fluid flow through the block limiting how much heat the coolant can absorb and transfer to the radiator.

Hope it helps, good luck!

Was wondering why my car was running hot (right around red zone). Removed a failed thermostat on a trip into NYC, figured it'd just run colder without it. Was actually starting to think it might have been a failing water pump.

Will have to get a new one and see if that helps.

garagespecrich · 07-26-2012, 03:06 AM

It has been super hot too....My jeep does it sometimes with the AC on...

jr4jc · 08-08-2012, 10:30 PM

after new alternator, because the old one was overheating when airconditioning was on, had NO overheating issues until;
when it is 100 degrees or very close to it, like 97 and over, the temp gauge rises but again only when the air conditioning is on, AND; the temp rises to 222 degrees. it looks bad on the gauge but my accessport shows 222 degrees.
QUESTIONS; is 222 TOO warm or ok
it never ran warm like this before??

jr4jc · 08-09-2012, 02:12 AM

under 95 degrees = no problems.

jr4jc · 10-01-2012, 09:08 AM

is 222 TOO warm or ok

WRXSD · 10-02-2012, 12:43 PM

I had this problem recently in very hot 100+ temps in traffic. I checked the intake air temp on my AP and it said 180 deg. Turned off the ac and it immediately dropped, but I had cooked my Grimmspeed Therm in the process. Your only option is to probably go with an all aluminum radiator, and that may not even do it. It may be a limitation on the stock cooling system. The ac compressor may be putting too much of a load on the engine for it to overcome in really warm, slow speed conditions.

222 is not TOO warm, but your rad fans do turn on at about 210 when the ac is not on. So the system wants to see a lower temp than that.

mechatricity · 10-04-2012, 10:29 AM

Right, i agree that 222 is not TOO warm, but is IS warmer than the stock system is designed to run. Granted you don't have a "stock" system but i don't see any reason why it would be running warmer than designed.

WRXSD, IAT of 180+ degrees in hot traffic is completely normal for a heatsoaked engine. I don't see how this would have any impact on your thermostat. OP already has a mishimoto radiator, IE all aluminum. A completely stock cooling system should have no issue dealing with ambient temps up past 115F under normal load. I have done plenty of AC- on driving in these temps with no issue...until my thermostat failed eventually, but not related to temperature i don't believe.

If either of you have a protune, check your AC ON idle speed. It should be ~1100 rpm IIRC.

shooting · 10-04-2012, 11:10 AM

possible sticky thermostat. and 222 IS HOT! the fans come on at 207 so .... its supposed to max around there and GO DOWN in temp. not hold till 222!!! do you have any extra volume of coolant in the system? i think our systems dont have enough coolant volume to keep it cool. especially with ac.. and some 100+ temps.

07-15-2012, 05:55 PM	#1
jr4jc Scooby Newbie Member#: 76834 Join Date: Dec 2004 Location: nashville, tn Vehicle: 2005 STI crystal metalic gray	Overheating, Only when air conditioning is on 2005 sti stage 3 with new water pump. have mishimoto racing radiator and; Overheating, Only when air conditioning is on. fans are coming on correctly. coolant; overflow was empty, upper radiator was full filled overflow, ran it for 10 minutes with heater on, and it took up half the over flow. still running warm to next line up, not in the red so next filled overflow again and ran it for 25 minutes with radiatior cap off, and heater on. didn't take up anymore, didn't see level drop any. overheating is taking place with easy driving, highway or local doesn't matter, but having the air conditioner on does. when it overheats it just goes up to the next line, never into the red when it does if i turn off the air, it cools right back to normal. could the compressor pull enough to make the water pump belt not turn the water pump correctly. i have a thermastat and am ready to change it but i can't see how that be the problem??? HELP!! * Registered users of the site do not see these ads.

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07-15-2012, 11:44 PM	#2
jr4jc Scooby Newbie Member#: 76834 Join Date: Dec 2004 Location: nashville, tn Vehicle: 2005 STI crystal metalic gray	i think its air in the cooling system, after my original post i spent about an hour warming engine and massaging air out of the upper pipe, refilling, letting it cool and warming back up. got a lot of air out of the system.

07-21-2012, 11:49 PM	#3
jr4jc Scooby Newbie Member#: 76834 Join Date: Dec 2004 Location: nashville, tn Vehicle: 2005 STI crystal metalic gray	OK anybody that could of figured this one out deserves a prize. So i take the car back to where I had freon put in the cooling system and WE start looking at everything. no air to speak of in the cooling system, fans checked out, nothing making sense, we get an infared gun and start measuring temps. find a 250 ish somewhere behind the belts and the fans....cant quite figure out where its coming from cause of moving belts and moving fan....raise the gun a little and.......its the alternator. 310 degrees at 2000 rpm. we disconect and drive it 10 miles with the air on, NO overheating. wow how strange, got a new one from subaru, holy crap this thing better mow the lawn and walk the dog...but no more overheating.

07-22-2012, 12:16 AM	#4
rymaggi Scooby Specialist Member#: 253442 Join Date: Jul 2010 Chapter/Region: BAIC Location: El Dorado Hills / Folsom / Sac Vehicle: 2006 vf39 Wrx Wagon UGM	I'm having the same problem. Fans come on correctly. But when I'm stuck in traffic, car starts over heating, but when I start driving again it starts cooling down.

07-23-2012, 04:57 PM	#7
treedspeed Scooby Newbie Member#: 215120 Join Date: Jun 2009 Location: 18301	i'm not sure it would. how about fan switch? though not sure if that would also create the issue op described.

07-24-2012, 03:28 PM	#8
SubyMass Scooby Newbie Member#: 136493 Join Date: Jan 2007 Chapter/Region: NESIC Location: Northborough, MA Vehicle: 2005 2.5 RS PSM	Doesn't sound like this is your problem but maybe it leads you in the right direction. If a radiator is getting clogged and doesn't let enough flow through it, having the extra thermal load (or increased air input temp) from the AC condenser can make the car overheat. Also a broken thermostat that's open (or if the thermostat is missing) will allow for too high of a fluid flow through the block limiting how much heat the coolant can absorb and transfer to the radiator. Hope it helps, good luck!

07-26-2012, 03:06 AM	#10
garagespecrich Scooby Newbie Member#: 327252 Join Date: Jul 2012 Location: The South Vehicle: 1993 Mazda Rx7 Red	It has been super hot too....My jeep does it sometimes with the AC on...

08-08-2012, 10:30 PM	#11
jr4jc Scooby Newbie Member#: 76834 Join Date: Dec 2004 Location: nashville, tn Vehicle: 2005 STI crystal metalic gray	after new alternator, because the old one was overheating when airconditioning was on, had NO overheating issues until; when it is 100 degrees or very close to it, like 97 and over, the temp gauge rises but again only when the air conditioning is on, AND; the temp rises to 222 degrees. it looks bad on the gauge but my accessport shows 222 degrees. QUESTIONS; is 222 TOO warm or ok it never ran warm like this before??

08-09-2012, 02:12 AM	#12
jr4jc Scooby Newbie Member#: 76834 Join Date: Dec 2004 Location: nashville, tn Vehicle: 2005 STI crystal metalic gray	under 95 degrees = no problems.

10-01-2012, 09:08 AM	#13
jr4jc Scooby Newbie Member#: 76834 Join Date: Dec 2004 Location: nashville, tn Vehicle: 2005 STI crystal metalic gray	is 222 TOO warm or ok

10-02-2012, 12:43 PM	#14
WRXSD Scooby Newbie Member#: 136539 Join Date: Jan 2007 Location: San Diego Vehicle: 2005 WRX Wagon CGM Stg. 2	I had this problem recently in very hot 100+ temps in traffic. I checked the intake air temp on my AP and it said 180 deg. Turned off the ac and it immediately dropped, but I had cooked my Grimmspeed Therm in the process. Your only option is to probably go with an all aluminum radiator, and that may not even do it. It may be a limitation on the stock cooling system. The ac compressor may be putting too much of a load on the engine for it to overcome in really warm, slow speed conditions. 222 is not TOO warm, but your rad fans do turn on at about 210 when the ac is not on. So the system wants to see a lower temp than that.

10-04-2012, 10:29 AM	#15
mechatricity Scooby Specialist Member#: 290592 Join Date: Aug 2011 Chapter/Region: TXIC Location: Dallas, TX Vehicle: 2006 WRX Wagon 2004 WRX Wagon	Right, i agree that 222 is not TOO warm, but is IS warmer than the stock system is designed to run. Granted you don't have a "stock" system but i don't see any reason why it would be running warmer than designed. WRXSD, IAT of 180+ degrees in hot traffic is completely normal for a heatsoaked engine. I don't see how this would have any impact on your thermostat. OP already has a mishimoto radiator, IE all aluminum. A completely stock cooling system should have no issue dealing with ambient temps up past 115F under normal load. I have done plenty of AC- on driving in these temps with no issue...until my thermostat failed eventually, but not related to temperature i don't believe. If either of you have a protune, check your AC ON idle speed. It should be ~1100 rpm IIRC.

10-04-2012, 11:10 AM	#16
shooting Scooby Newbie Member#: 82720 Join Date: Mar 2005 Chapter/Region: RMIC Location: a mile high COLORADO! Vehicle: 1993 any 93 + subaru dirty or snowy	possible sticky thermostat. and 222 IS HOT! the fans come on at 207 so .... its supposed to max around there and GO DOWN in temp. not hold till 222!!! do you have any extra volume of coolant in the system? i think our systems dont have enough coolant volume to keep it cool. especially with ac.. and some 100+ temps.