engine temp
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Only if you're moving slowly or not at all. The AC forces the cooling fan(s) on, so when sitting or moving at low speeds, the fans run when they would otherwise, not. In that case, turning off the AC allows the temps to rise to "Fan on temp" which is around 230*F.
Traveling at speed however, turning off the AC should result in a slight temp decrease.
Traveling at speed however, turning off the AC should result in a slight temp decrease.
Racer
Joined: Mar 2014
Posts: 409
Likes: 7
From: Taunton MA
Friday It was over 90 degrees, I put the AC on in my '94 vert as soon as I came off the highway (after traveling about an hour) the temp rose from about 200 to 213, which is hotter than normal because my fans come on at 205. As a little test, when I was about a mile from my destination I turned off the AC and the temp returned to 205.
I would think that the heat dissipated from the AC then travels over the radiator and makes the cooling system work harder. especially after coming off the highway.
I have also noticed that using the heater on evenings that get a little cooler cause the car to run a little cooler. Again, I would think that the heater box is acting like a radiator and helping to dissipate the heat.
Thoughts?
I would think that the heat dissipated from the AC then travels over the radiator and makes the cooling system work harder. especially after coming off the highway.
I have also noticed that using the heater on evenings that get a little cooler cause the car to run a little cooler. Again, I would think that the heater box is acting like a radiator and helping to dissipate the heat.
Thoughts?
Race Director
Joined: Oct 2008
Posts: 17,982
Likes: 1,072
From: Lansing MI
Friday It was over 90 degrees, I put the AC on in my '94 vert as soon as I came off the highway (after traveling about an hour) the temp rose from about 200 to 213, which is hotter than normal because my fans come on at 205. As a little test, when I was about a mile from my destination I turned off the AC and the temp returned to 205.
I would think that the heat dissipated from the AC then travels over the radiator and makes the cooling system work harder. especially after coming off the highway.
I have also noticed that using the heater on evenings that get a little cooler cause the car to run a little cooler. Again, I would think that the heater box is acting like a radiator and helping to dissipate the heat.
Thoughts?
I would think that the heat dissipated from the AC then travels over the radiator and makes the cooling system work harder. especially after coming off the highway.
I have also noticed that using the heater on evenings that get a little cooler cause the car to run a little cooler. Again, I would think that the heater box is acting like a radiator and helping to dissipate the heat.
Thoughts?
This guys thesis is 100% correct.
Team Owner
Joined: Aug 2005
Posts: 34,988
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From: Riverside County Southern California
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Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
No it's not. The heater core heat rejection is meaningless. Yes, there is some heat rejection, but it is tiny compared to what you'd get, running the fans w/the AC.
The fans run w/the AC on, and lower the operating temp (at low speed) compared to not running the AC. Yes, the AC sheds some heat that the Radiator has to cope with, but the radiator is designed with for that and it can manage it.
I can sit in traffic w/my AC on, and my temps stay below 195. Turn it off...temp goes on up to "fan on" temp, which on a stock car is ~230*F.
The fans run w/the AC on, and lower the operating temp (at low speed) compared to not running the AC. Yes, the AC sheds some heat that the Radiator has to cope with, but the radiator is designed with for that and it can manage it.
I can sit in traffic w/my AC on, and my temps stay below 195. Turn it off...temp goes on up to "fan on" temp, which on a stock car is ~230*F.
Race Director
Joined: Oct 2008
Posts: 17,982
Likes: 1,072
From: Lansing MI
No it's not. The heater core heat rejection is meaningless. Yes, there is some heat rejection, but it is tiny compared to what you'd get, running the fans w/the AC.
The fans run w/the AC on, and lower the operating temp (at low speed) compared to not running the AC. Yes, the AC sheds some heat that the Radiator has to cope with, but the radiator is designed with for that and it can manage it.
I can sit in traffic w/my AC on, and my temps stay below 195. Turn it off...temp goes on up to "fan on" temp, which on a stock car is ~230*F.
The fans run w/the AC on, and lower the operating temp (at low speed) compared to not running the AC. Yes, the AC sheds some heat that the Radiator has to cope with, but the radiator is designed with for that and it can manage it.
I can sit in traffic w/my AC on, and my temps stay below 195. Turn it off...temp goes on up to "fan on" temp, which on a stock car is ~230*F.
I was speaking to his thesis regarding the cooling system. Perhaps I should have used a simpler word such as "theory". I couldn't care less about the specific conditions he has described. Amazingly, your own post admits that the ac sheds heat the radiator has to deal with and you also admit that the heater core does too, and yet somehow he's wrong ?? .... I'm sorry I ever commented on any of your posts and I wont do it again since you clearly know everything already. I will tell you this though, if your car is ever overheating you best turn your ac off and your heater on.
Good luck.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Oh good lord.
I was speaking to his thesis regarding the cooling system. Perhaps I should have used a simpler word such as "theory". I couldn't care less about the specific conditions he has described. Amazingly, your own post admits that the ac sheds heat the radiator has to deal with and you also admit that the heater core does too, and yet somehow he's wrong ?? .... I'm sorry I ever commented on any of your posts and I wont do it again since you clearly know everything already. I will tell you this though, if your car is ever overheating you best turn your ac off and your heater on.
Good luck.
I was speaking to his thesis regarding the cooling system. Perhaps I should have used a simpler word such as "theory". I couldn't care less about the specific conditions he has described. Amazingly, your own post admits that the ac sheds heat the radiator has to deal with and you also admit that the heater core does too, and yet somehow he's wrong ?? .... I'm sorry I ever commented on any of your posts and I wont do it again since you clearly know everything already. I will tell you this though, if your car is ever overheating you best turn your ac off and your heater on.
Good luck.
His theory may have merit, but the effects of what he's theorizing are meaningless, RELATIVE to the effects of the cooling fans running...which is directly related to the OP's post and the point of the whole thread. In most low speed situations, in a C4, turning the AC on, will lower operating temps, and turning the heat on, won't. That's this thread. As for turning your heat on for better cooling when overheating....maybe. Totally depends on the cause for overheating.
Last edited by Tom400CFI; Jun 15, 2015 at 11:20 PM.