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Using the AC for heat

I don’t see what you’re disagreeing with. As you and I have both said, there is no heat created .

While it is not strictly in conformance with thermodynamic laws, I think of temperature as “heat density”, and heat itself as “packets”. In a volume of air, say 1 liter, at some given temperature, the heat packets would be evenly distribute thoroughout. Compress that volume and you’d reduce the volume but retain the same number of “packets”, increasing its density, thus raising the temperature. Blow ambient temperature air over that newly hotter volume and you’ll cool it. Allow it then to expand and the “energy density” will lower, hence the lower temperature.

This will always, as I’ve said, be relative to ambient temperature. Since the entire process never starts with anything absolute, but only with ambient, which is of course relative.

And I’m pretty sure there’s no "d’ in refrigerant.

Does the owners manual describe this method to heat the vehicle?

Put a temperature gauge in the vents and try with A/c on and off. See what method works best. I can see the theory of dry air, but warm moist air in winter time works best.

post your results of this experiment.

Now you guys are getting into the specifics of how A/C works…and thats fine. But to reiterate…the main point of this was that the A/C system makes his interior heat up faster. VIA some component of the A/C system…and this is simply not true.

One guy mentioned the heat generated by the compression of the refridgerant somehow getting into the cabin to heat the air for you…NOT TRUE…the heat generated is not in any way connected to your cabin air…Those in the know know all of this…we are just trying to get those not in the know to understand why this is…and concordantly why this is a wasteful behavior or belief

The only way this fooled the guy into doing this was because it did give him heat in the car faster…however it was only thru added load on the engine…the A/C compressor put a load on the engine heating up the coolant faster…thus providing heat in the cabin faster via the heater core…the load or drag of the A/C is akin to driving the car up a hill when you are sitting in the driveway.

The A/C has no ability to add heat directly to the cabin of the car. The only item that does this is as we all know is the heater core. If you notice warm air in the car faster with the A/C on …it is because you are stressing the engine out more via compressor drag on the engine…which will cause it to heat up faster… while in the driveway. This is stupid and wasteful…but if you have the money and dont care about silly behaviors…A/C AWAY…

While I agree that the heat energy within the mass becomes more dense, it’s also true that the energy used to compress the fluid is converted into heat within the fluid. The refrigerant does, in fact, end up with more heat energy in total than it had in its uncompressed state.

Honda, you are right. We’ve gotten off on a tangent and are currently debating physics.

The OP had three questions; does it make sense from the standpoint of heating the car up, does it heat the air any differently, and will it cause harm to the AC system.

I agree, and I suspect we all do, that the heat generated by the compression of the refrigerant is dissipated by the condensor and does not contribute to heating the cabin. The added load on the crank may help the engine warm up a tad faster, but I’d question whether the difference would be noticable. Perhaps I’ll play with this over the winter and see if I can tell.

I’d debate whether doing any activity to warm one’s cold appendages up faster is wasteful behavior. I, for one, will use my mechanical and economic assets to warm my anatomical assets without guilt.

And as to the question of damaging the AC system, I think we all agree emphatically that turning the AC on while using the heat will not damage the AC system.



Whoa, wait a daggone minute B Bird. I want results with a temperature check with A/C on and off.

OP’s husband needs to prove his point. We all know it has no effect on the A/C system,since the defrost uses the A/C.

We’re at 46 replys now, 47 including this one. The OP has long since moved on.

I’m with Honda. It’s time to put this thread to bed.

No need for a temp check…maybe a time to heat up check but…the question was… “Does the AC heat up a car any differently than just having hot air coming through the vents?”

The answer is Yes and NO (NO only because of some other guys interpretation and answer in a post which was incorrect)…it heats up the car/engine faster due to the additional load the A/C compressor adds to the engine. This heats the coolant and cabin…

and No…it doesnt actually ADD heat to the cabin directly (another poster made this comment actually in an answer and it had to have been addressed)…it makes the engine heat up faster …just like driving up a hill would because of load.

** I dont think the OP thought that the A/C actually added its heat from the condensor to the cabin air temp…the other poster stated that the condensor heat got into the cabin somehow…which aint happnin.

Can it go to bed now?

u guys have me more confused then when i asked. my girlfriend always leaves the a/c on year around and in winter just moves the temp dial to blows hot air but im not sure how and if it taxes the system?

It takes a little more power from the engine, that’s all. The AC compressor runs when using the defrost cycle. Leaving the AC on does dehumidify the air inside the car.

Would be better to start a new thread, rather than add to an old thread.