What's an a/c condensor?

[gforces944]

I may need to replace this item to get my a/c working, so i'm wondering, what IS an a/c condensor--what does it do?

[scottmandue]

Uh... I have been retired from a/c work for about ten years so may be all bass akwards but...
the coil on the outside is called the condenser and the coil on the inside is the evaporator. Some times there is a reservoir on the condenser side that stores the excess gas. I may be completely wrong if you have to know I could dig up my old a/c books and check.

[gforces944]

thanks, i do believe that the shop said it may be the condenser, inside the car--does the 944 have the condensor and evaporator located under the dash? They can't seem to find any leaks in the engine compartment using their show-glow dye and black light.

[AFJuvat]

Condensor is right in front of the radiator.

The evaporator is behind the dash

Condensor - hot
Evaporator - cold.

AFJuvat

[Lew]

The condensor is pretty easy to replace once the system is discharged. I took off the spoiler and it didn't take too long after that.

[Lawrence Coppari]

AC, refrigerators, and heat pumps work as follows:

The compressor raises the pressure of the refrigerant vapor (gas) to what is called a superheated vapor. The temperature rises along with the pressure. Superheated means that the vapor's temperature is above the temperature at which it would want to be a liquid at that pressure. It means it exists soley as a vapor. Saturated means the refrigerant is happy to exist as either a vapor or liquid and equilibrium can exist between the two phases. Superheated vapor leaves the compressor and goes to the condenser where heat is removed until the vapor becomes a liquid (condenses). From here is goes to the receiver dryer where moisture is removed by a dessicant in the little vessel. Generally, the sight glass is mounted close by so you can see bubbles go by if your refrigerant is low. A lot of heat has to be removed when the phase is changed from gas to liquid (and vice versa). The refrigerant is a saturated liquid at this point meaning that a slight drop in pressure will cause it to become a vapor again if sufficient heat (energy) is available.

Next, it passes through the expansion valve which is a tiny hole. Whenever you push a fluid through a contraction (orifice), there is an associated pressure drop. Viola, the saturated liquid wants to be a gas after being shoved through the orifice. But the gas has a much higher energy state than the liquid so there needs to be an energy input to evaporate the liquid. It cannot happen in the tubing because there is not enough tube area to absorb heat from the surrounding air.

At this point the refrigerant is in your dashboard. It goes to another heat exchanger similar to the condenser that is in front of your radiator but this one is called an evaporator. The evaporator merely increases the exposure of the refrigerant (that really wants to be a gas again because of its pressure but cannot without energy input) to heat in form of air temperature inside your car. As the refrigerant passes through the evaporator, it picks up heat from the air in your car and returns to its gaseous state. From here it returns to the compressor and starts the cycle again.

With a heat pump in heat mode, the condenser is inside your house and the evaporator is outside absorbing heat from the atmosphere to effect the phase change. There is a valve mechanism that reverses the flow of refrigerant depending on whether you want heating or cooling.

[scottmandue]

Thanks Lawrence,

Phew... I didn't want to climb the rafters in the garage to dig out the refrigeration books.

BUT HEY I remembered the whole evaporator condenser coil thing!

Hoo Hoo!

So much for that short term memory loss cra....

Uh... nevermind.