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an old trick on cold mornings


justgreat

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last week on an exceptionally cold afternoon while picking up my son from track practice i froze my feet off waiting for the heater to get up to speed. it was a short drive and it took forever for the coolant temp to get up to 180..then i remembered the "trick": shut off the c/c system until the operating temp reaches 170 or so, then turn the system back on...the heater will be able to throw much more heat than letting the system regulate when it turns the heater on. this is only on extremely cold days that you might need to use this "trick"; but i have started doing it everytime lately on start-up, simply because the coolant system reaches 180 much quicker. jackg 90seville 99k

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last week on an exceptionally cold afternoon while picking up my son from track practice i froze my feet off waiting for the heater to get  up to speed. it was a short drive and it took forever for the coolant temp to get up to 180..then i remembered the "trick": shut off the  c/c system until the operating temp reaches 170 or so, then turn the system back on...the heater will be able to throw much more heat than letting the system regulate when it turns the heater on. this is only on extremely cold days that you might need to use this "trick"; but i have started doing it everytime lately on start-up, simply because the coolant system reaches 180 much quicker.  jackg 90seville 99k

Hey,

I thought the thermostat remained closed so that coolant will only flow through the engine, thus heating it up faster. I don't see how this trick would make a difference due to the fact that the heater core is not warming up and therefore there is no heat being taken out of it into the air. Could someone please explain? Thanks.

Edit: or does it flow through the engine and heater core? This would make sense. I don't know the coolant flow exactly in my head.....there are alot of different directions...haha

Chris

Christopher Petro

94 sts

67 coupe de Ville

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last week on an exceptionally cold afternoon while picking up my son from track practice i froze my feet off waiting for the heater to get  up to speed. it was a short drive and it took forever for the coolant temp to get up to 180..then i remembered the "trick": shut off the  c/c system until the operating temp reaches 170 or so, then turn the system back on...the heater will be able to throw much more heat than letting the system regulate when it turns the heater on. this is only on extremely cold days that you might need to use this "trick"; but i have started doing it everytime lately on start-up, simply because the coolant system reaches 180 much quicker.   jackg 90seville 99k

Hey,

I thought the thermostat remained closed so that coolant will only flow through the engine, thus heating it up faster. I don't see how this trick would make a difference due to the fact that the heater core is not warming up and therefore there is no heat being taken out of it into the air. Could someone please explain? Thanks.

Edit: or does it flow through the engine and heater core? This would make sense. I don't know the coolant flow exactly in my head.....there are alot of different directions...haha

Chris

I do not see how it works either... If you ask me, the fastest way is dropping to the third or second gear (increased RPM will push more coolant through the heater core) and driving hard (if conditions allow) to load the engine as much as possible. And, sure the C/C needs to be at 90 degrees to open the airmix door completely.

The saddest thing in life is wasted talent

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you could be right about the thermostat...i do know that the c/c will throw out more heat faster IF i shut the c/c off and let the coolant system reach o/temp asap and then turn the climate control on.

when the engine is cold, the LAST thing i would do is run around in 2nd or 3rd gear...not good. just drive right off...don't let the engine idle when she's cold...just keep the revs under 2k or so for the first mile or so. jackg 90seville 99k

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The engine block will heat up faster with c/c off, which

allows him to drive harder to warm things up even more.

Really is a good point.

I agree that turning blower on does slow down a little bit warming the engine up. But even at lower temperatures than say, 180 you still get some heat into the cabin. Does it make sense to suffer for five minutes to let engine warm up a little bit faster? I am not sure, but I would not be surprised if the temperature of the air in the cabin would be the same say, in 10 minutes regardless of all the tricks. I personally turn the blower on only to keep the windshield transparent.

The saddest thing in life is wasted talent

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The same reasoning if your car is overheating in the summer, you turn on the heater it acts as a second radiator. So when your coolant is running thru the heater in a cold car the coolant is further cooled taking longer to heat up

You may have a point but waiting about 2-3 minutes for the coolant temp to reach 120 degrees before the heater comes on is sometimes not the better idea. I'll take anything I can get A.S.A.P. on the freezing days, which means once I start the car and the water temp hits 80 or so the heat goes on. I'll take 60-degree air coming from the vent over nothing any day. ;) I'll crank it to 90 and let it go. Today, I just let the heat turn on automatically which is when the water temp hits about 120 degrees. But there are times that I just can't wait. :blink:

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The same reasoning if your car is overheating in the summer, you turn on the heater it acts as a second radiator. So when your coolant is running thru the heater in a cold car the coolant is further cooled taking longer to heat up

But there are times that I just can't wait. :blink:

I heard that! :D

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Yup, there are some cold days I really hate having the "heat" come on when the water temperature is only 105 degrees. What blows on my feet can be uncomfortably cold, so I turn the C/C OFF until the water temerature reaches 125 degrees or so.

However, I have a still better trick on cold days: I wear warm footwear. Try it. It works!

Regards,

Warren :D

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My '97 won't produce ANY air from the vents until the air is warm enough to be considered heat, as long as I leave the HVAC in AUTO mode. In other words, temp on 72, AUTO mode, start engine. The air mix door will go to feet (heater mode) and the fan will run very slowly for the first 2-3 minutes until there's enough warm coolant in the heater core to produce heat, and then it will run.

I bet if you guys put your HVAC systems on AUTO, it'd work the same, and you'd get heat faster.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Yup, there are some cold days I really hate having the "heat" come on when the water temperature is only 105 degrees. What blows on my feet can be uncomfortably cold, so I turn the C/C OFF until the water temerature reaches 125 degrees or so.

However, I have a still better trick on cold days: I wear warm footwear. Try it. It works!

Regards,

Warren :D

you hit the nail on the head. that particular day i had my deck shoes on!! instead of my boots...dumb,dumb,dumb. my system is the same...when in auto it will go start to blow "heat" at about 118 degrees for the coolant...but in reality there's nothing but cold air coming out until she reaches operating temp.

i now make sure i have my booties on...jackg 90seville 99k

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There are things in the system that I would love to change, that is one of them. Have the heat come on at 160 or so..

However, I think I read that the system comes on at 112 to start defogging the windshield, if that is the case why isn't defrost mode the default until the temp reaches 190, and then floor heat comes on... I have to re-read the FSM on this.

With this system that would be very easy to do. So then instead of getting a cold blast on your feet you would get a cold blast on your face!

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The air out of mine is luke warm whenever it does come on...at 118*F coolant temp I guess? It's not real hot, but it's not cold either.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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An interesting topic,

I can understand why the majority support letting the coolant warm up. However, I tend to agree with Adallak and Jason A. I also feel that the Caddy is fairly smart about not distributing any more cold air than required. This system was probalby optimized for driver comfort with no tinkering required.

Although the blower air feels relatively cool (or downright dang cold), it is probably always the same temperature or at least slightly warmer than the cabin air within a few moments of the engine operating.

A key debate point would be to determine if the "fresh air inlet door" is opened before the "heat" is allowed in auto (I doubt it). This fresh air exchange along with the A/C work to remove interior moisture to "defog" the cabin.

Regardless, I believe that the net btu's delivered in 10-minutes will probably be higher in Auto, than manipulating the system. Either way - it would be important to take these measurements carefully - without personal bias.

To reiterate the above, - moving air of the same temperature always feels colder, due to convection currents drawing heat away from your exposed skin that has heat supplied to it (our personal connection with that pesky enthaphy thingie).

I think of this as an interior version of "wind chill" for a limited period of time.

All IMHO :rolleyes:

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There are things in the system that I would love to change, that is one of them. Have the heat come on at 160 or so..

However, I think I read that the system comes on at 112 to start defogging the windshield, if that is the case why isn't defrost mode the default until the temp reaches 190, and then floor heat comes on... I have to re-read the FSM on this.

With this system that would be very easy to do. So then instead of getting a cold blast on your feet you would get a cold blast on your face!

yeah, the defroster mode is the "fail safe"...as soon as the engine is started you can direct air to the defroster vent, no matter what temp the coolant is..this is for safety reasons...l learned this when the air handler box under the defroster vent crapped out and all i had was the defrost vent blowing ANYTHING...hot, cold, lukewarm. again, i only tinker with the auto setting when my feet are cold...normally i set it and forget it...oh wait a minute...that's the roast. jackg 90seville 99k

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