Using the AC for heat

That explains it. Thanks, I’ll give it try!

Are you guys out of your minds? The AC system puts a load on the engine…and may make it heat up faster…The AC system will in NO WAY directly provide you with HEAT IN THE VEHICLE…yes you got the compression of a gas and then its decompression correct but NONE of this translates into any kind of providing HEATED AIR inside your cabin VIA the A/C system…

I hope I am reading your posts correctly…if you are stating that the AC system provides any type of heated air to enter the cabin…YOU ARE DEAD DEAD DEAD WRONG… It does create heat but that heat is dissipated outside your car in the evaporator assy and never enters the vehicle… The condenser inside the car is what will pull heat from the air creating cool air…thus AIR CONDITIONING.

The only thing I think the original poster was referring to was her husbands use of the AC to get the engine warmer faster…which it could do because of the added load on the engine…which would then provide you with warm air in the cabin via the heater core… ALL of this is assinine actually…use the A/C when you are HOT…or when your windows are fogged…any other use of it is simply burning up your money and lighting your cigar with it…

I think Im reading between the lines correctly…meaning the interpretation of what each group thinks is happening or how the systems work tho I might be confused…what I am NOT confused about is how the A/C system works, where heated air comes from, What A/C is for…and how to use it correctly. This idea of A/C on to provide you with heat is or can only be interpreted correctly as the A/c makes the engine work harder thus creating heat…which is transferred to the cabin via the heater core…you get none of the heat generated by the A/C system into your car…thats outside and in the evaporator…never entering your vehicle…

C’mon guys…

Another cup of java?

Seriously, I think the OP was simply questioning her hubby’s use of the AC in the winter. She was, I think, concerned that it was damaging the AC system. She didn’t realize the two don’t fight against one another, one simply cools the air using the themodynamics of expanding fluid, and the other warms it using heat from the engine coolant, each oblivious to the other.

Hubby probably learned that as the way to eliminate fogging of the windshield, and that would make sense. I’ve never heard of using the AC to warm the engine up faster, although that would make sense too.

Anyways, hubby’s affectation is unusual harmless. Although it does use a bit more gas due to the added load on the crank.

Your evaporator could get to reach 300 degrees…and NONE of that heat will EVER enter your cabin… YOu have managed to mix a few facts with complete ignorance…

Yes the compression of the refrigerant creates heat in the evaporator…NO you do not have the ability to IMPORT that evaporator air into your cabin…it is cooled by your evap fan…and or rad fan…never ever entering your cabin.


The only way you can perceive that the A/C is helping your heat …get hot faster…is by the A/c providing your engine with a load…which would be creating more heat…which is dumped into your coolant…which flows thu your HEATER CORE…providing you with heat in the car faster than without A/C on…this is akin to driving your car up a hill… while you are in the driveway.

Some of you need some SERIOUS schooling here…

Sorry but thems the facts Ma’am

Its a waste of fuel and time…the difference in heat up time would be negligable in my book.

Will it damage anything? No I guess not but why use something that you dont need…DO you also turn on all of your TV’s in your house when you arent watching them…same thing…

What I am reacting to is the mixture of total BS with some correct info… Lets get things right here…

and no I dont drink coffee…LOL…this one just really got me going because of the obvious flaws in the flow of logic… I guess thats all… Sorry… I dont want something like this to propagate out and finally reach my girlfriend…then I’d have to choke her or something cause she’d argue with me about it :)…LOL

C’mon OK45 and Common Sense…back me up…

Honda, did you mean that the condensor can reach 300 degrees? The condensor is the heat exchanger that cools the hot compressed fluid with outside air, the EVAPORATOR
gets fed cooled, compressed fluid to be expanded (into vapor) wherein its temperature drops, the now-chilled refridgerant to draw heat out of the cabin air… I’ve been guilty of inadvertantly reversing those two nomenclatures myself.

The logic is simple: compress fluid and heat it up, remove its heat and draw its temp as close to ambient as possible, allow it to expand rapidly and chill a coil, pass the cabin air past the coil to remove some of its heat, then recompress and do again. The removal of cabin moisture through desposition of it as condensation on the coils is a byproduct of dropping the cabin air temperature via the coils.

Did I miss anything?

That was an arbitrary EXAMPLE of no matter how hot your condensor is… Oh wait did I juxtapose the two? I didnt mean to…

LOL…I think I did…duh I do that all the time when talking about A/c…I knew what I meant tho I think you did too. You get the idea…the heat of the denser can never get into the cabin because it is in the front of the car in front of the radiator…it adds nothing to the air temp of the car directly…

You knew what I meant…lol

No you didnt miss anything…I was too busy ranting to see that I swapped the two…but the rest is all still good info…I,m just a moron…

Condenser-Spencer Evaporator-Sh-maperator…you knew what I meant…just switch my usage around and it will all hold water… LOL

I truely did know what you meant. And I mix the two nomenclatures up all the time too. I think the fact that the condensation happens in the evaporator and not the condensor screws me up.

Hey, a part by any name still performs the same function. The same basic part is often called different names by different manufacturers. I’d rather trust my car to someone who understands how everything works than to someone who’s memorized the part names.

YA…Im an idiot. Now that I think of it I always juxtapose the two especially when I talk to people about it. If I had to order parts…somehow I’d order the right ones…dunno why that is.

Condensor: Used to cause a gas to condense into a liquid.

Evaporator: Used to cause a liquid to evaporate back into a gas.


Right. It’s the condensation on the OUTSIDE of the evaporator that always screws me up. I know, I said IN the evaporator and not ON the evaporator. I’ll get them straight someday. I hope.

Oh, heck. Now I’ll be screwed up for the rest of the day.

Honestly, I suspect that juxtapositioning these names may be common.

Perhaps because you’re ordering from the “exploded view” drawings?

I was unaware automotive A/C systems could reverse the direction of the freon flow and produce heat in the evaporator…You learn something new everyday!

Tester, this is one of the few times you have posted pure BS…In the winter time , the evaporator will quickly drop below freezing and a sensor will shut off the compressor…A system that could only reach 40-50 degrees would be useless in the summer…When that refrigerant liquid expands into a gas, it absorbs heat, it can not produce heat…

When refrigerant evaporates in the evaporator, it absorbs heat, whatever heat there is…This process can never add heat to the air flowing through the evaporator. The evaporator can drop 100 degree summer air to 45 degrees, but it CAN NOT heat zero degree winter air to 45 degrees. That’s not how refrigeration works unless you reverse the compressor and turn the evaporator into the condenser…(which many home systems do)

Tester, if I understand your description of air conditioning it defies physics. Please correct me if I have this wrong.

You’re saying that the refrigerant is compressed, making it hotter. The hot compressed refrigerant is then cooled to roughly ambient temperature by the condenser. The ambient temperature liquid is then allowed to expand in the evaporator, thus making it a lower temperature gas. This cold gas cools ambient air blown over the evaporator coils.

Assume an outside temperature of, let’s say, -100 degrees. The refrigerant is compressed and heated in the compressor, then cooled to roughly -100 in the condenser. The cooled liquid refrigerant is then allowed to expand in the evaporater, and you’re saying that this will result in 40 to 50 degree air?

This seems extremely unlikely to me. Please enlighten me.


That’s exactly what Honda and I have been saying. We’re just fooling aroud now with having juxtapositioned the names of the components. We’re just having fun now.

Tester seems to be assuming that the refrigerant will always evaporate to 40 to 50 degrees, regardless of the ambient temperature. Evaporation temperature must always be relative to ambient, not an absolute number that stays the same regardless of outside temp.

The compression / evaporation of refrigerant can never create heat, (aside from the friction of the compressor itself), but rather only transfers heat from one place to another.

Not quite.

Compression of the refrigerant heats it up, just as compressing air in a diesel heats it to ignite the fuel when it’s sprayed in and high compression engines heat low octane fuel to preignition. The heat isn’t “created”, rather it comes from the energy used to compress it.

This is basic thermodynamics. Compress fluids and they heat up. Decompress them and they cool down.

I refer you to paragraph 3.1.2 in the attached link.

This is basic stuff. I know this stuff well. The only thing I’m unsure of is whether there’s a “d” in the word “refridgerant”.