Vehicle HVAC System 1

[Guest1234567729473]

I am having trouble understanding the hvac system. I have a good understanding of the refrigeration cycle, however, I am confused with the placement of the condenser in a vehicle. If air conditioning is provided by blowing air over a condenser, why is the condenser located in front of the radiator under the hood? How does the cool air enter the cabin after blowing across the condenser? Wouldn't the air just disperse into the engine bay I realize I am uneducated on this and it is a simple answer, however, I am having trouble understanding the exact process of the hvac system in a vehicle. Any information would be appreciated. Thanks.

 

[LittleInch]

Try looking at this explaination

http://www.movacs.com/How it works/index.html

Heat is removed from the condenser, but cold air comes from the evaporator, which is located in the car air inlet system.

They put the A/C condenser in front of the radiator so it gets the first go at the air coming in. Yes, this means that the radiator see hotter air than it would otherwise, but is normally oversized. sometimes though you need to turn off the AC to avoid overheating the engine....

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Also: If you get a response it's polite to respond to it.

 

[Guest1234567729473]

Thank you for the link, it helped me understand the refrigeration cycle better. I am, however, still confused at how the air gets into the cabin and how it comes through the vents to the cabin. If the condenser is in the very front of the car, how does the the air that is heated by passing it get into the cabin? Or are there two separates systems in the vehicle? One for the engine bay and one for the climate control?

 

[dbill74]

Oh where to start and not write a text book here.

You have a 'good understanding of the refrigeration cycle'; so you know (I hope) there are two processes in the cycle in which heat energy is transferred into or out of the cycle. In practice, you have two heat exchanging coils to transfer heat to/from the refrigerant. These two coils are commonly called the evaporator and condenser; they are so named for the phase change that is happening to the refrigerant, and absolutely nothing to do with what is happening to the air or the water vapor in the air.

Most often the intent of an HVAC system is to provide cool air for occupant comfort, to do this heat must be removed from the air and absorbed by the refrigerant. This is done via the evaporator coil. This air will also be filtered for dirt and other pollutants. To do this, the evaporator coil, fan and filters are going to be enclosed and out of sight.

Now that heat has been removed from the comfort air stream and absorbed by the refrigerant, this heat needs to be rejected so the cycle can start over again. This heat rejection takes place via the condensing coil or condenser. the most common place to reject this heat is the atmosphere. At your house this is via an outside condenser unit, in your car the engine compartment is convenient enough.

Hope this helps.

 

[Guest1234567729473]

Once the air passes the condenser and absorbs the heat, the refrigerant is then cooled. Is the refrigerant then transported to a hidden coil that air is blown past and into the cabin to provide cool air?

 

[Guest1234567729473]

I am unfotunately just not grasping one simple concept. I understand that the air that passes the condenser absorbs the heat from the refrigerant. I do not, however, understand how this heated air is then blown into the cabin, seeing that the condenser is in the very front of the car.

 

[HVACMech]

Well... you have switched questions from the OP. Are you asking about heated air or cooled air. Like dbill said the evaporator makes the cool air. The "heated air into the cabin" comes from a heater core and not part of a DX cycle at all. I would if I were you stop telling people you have a good understanding of the refrigeration cycle though... Otherwise we wouldn't have this post

 

[berkshire]

Maybe this will help, the condenser sheds heat, the evaporator absorbs heat. if you do not understand these fundamentals, then you need to go back and re- read your AC text books.
B.E.

You are judged not by what you know, but by what you can do.

 

[Guest1234567729473]

@HVACMech you are correct, I thought I had a decent understanding but I guess I do not. I have not had any formal education with this process, just what I can find online. I understand the condenser sheds heat and the evaporator absorbs heat. I guess my real question with this all would be this:

Does the air conditioning and the heat that is supplied to the cabin of a car come from seperste processes/cycles? I understand that the evaporator is enclosed and hidden, and that the air that passes it loses it heat and therefore becomes cold, and is then blown into the cabin through the vents. My uncertainty is with the heat and how it gets blown into the cabin. If it is part of anther process then that clears it up for me. I assumed the air that passed the condenser and becomes hot was the same air that enters the cabin to provide heat...in which case I didn't understand how that air made it all the way to the cabin from the front of the car.

 

[HVACMech]

http://manchesterradiator.com/images/cooling_system.jpg

Here you go. Heat comes from a heater core which is attached to your radiator.

 

[Guest1234567729473]

Again I realize I am not as educated as everyone on here, but this is something I just wanted to understand for my own benefit. In addition, after re-reading my original post, I realize I did not clearly state what exactly I wasn't understanding. Thank you everyone for replying, I really appreciate it.

 

[Guest1234567729473]

Wow okay so there is a seperste heater core used to supply heat. I thought we utilized the heat that is dispersed from the condenser, which is where my misunderstanding came from.

I have seen pictures of what I believe are called hvac "units" that are located behind the glove box, under the dash. Does this unit contain the evaporator and the heater core, and air is blown past each in this unit and then vented into the cab? Thanks you for your all your help, I needed clarity from someone who is well educated with this area and I didn't know where else I could ask someone.

 

[LittleInch]

Ok,

The condenser for the AC unit sits at the front of the car. Air goes through it, removing the heat. This air then goes passed the engine and out into the open air behind the car. The engine compartment is sealed from the air above the bonnet (hood). Air inlets at the base of the windscreen suck in air from the outside. This air is different to the air which has gone through the condenser. This air goes through the evaporator where it gets cooled and is the item hidden inside the car, under the dash. This air goes into the car keeping the people inside nice and cool.

However if the air outside is cold and the inside of the car needs heating, then the AC is turned off and hot water from the engine which would normally go through the radiator, now goes through a heater, heating the air coming into the car from the outside keeping the occupants warm.

Does that help?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Guest1234567729473]

That helps very much. That is crystal clear and concise. I appreciate all the help. Again I'm sorry for my lack of knowledge with the subject, this is just something that I have been wondering for some time now. I appreciate all the help.