Information about your AC system. General R134a conversion information also.

[DSMRevolution]

I am posting this in General/Newbie Forum for the time being. Feel free to move it to the how-to forum or whatever forum you think it would fit best.






The AC (air conditioning) system in most cars is quite simple to understand, along with your DSM AC system. The basic parts to a AC system are as follows:

Evaporator - This converts liquid to a gas vapor. The liquid enters as a low pressure liquid and exits as a low pressure gas. Your evaporator will be found inside the dash assembly.

Compressor - There are MANY different types of compressors. A compressor basically turns a low pressure vapor into a high pressure vapor. This is the heavy oval shaped chunk of metal that is found mounted to the back engine block. It is turned with a clutch type setup pulley wheel and ran by a accessory pulley.

Condenser - The condenser is what converts the high pressure vapor into liquid form. It is found in front of the radiator.

Receiver dryer - This has a few purposes. The most important part of the receiver dryer is to filter dirt from the AC system. Found inside the dryer is what’s called a desiccant bag. This “bag”, helps keep moisture out of the system by absorption. NOTE: Found on top of the receiver dryer is a viewing hole. I will be explaining this later.

Thermal expansion valve - AKA TXV. This turns the high pressure liquid into a low pressure liquid. The TXV is controlled by a coil like temperature sensor.



That is the basic parts to a AC system. Newer systems no longer sport the receiver dryer or the thermal expansion valve. These are replaced by a accumulator and expansion tube (aka orifice tube).

One way to tell if the AC system is low, is to check the receiver dryer viewing hole. If you see bubbles through the viewing hole, your AC system is low on refrigerant. The typical DSM system takes about 2.06lbs (two cans at about $10 a can) and about 5oz of oil. Without this oil, your compressor would seize up.

R12 is a lot harder to find these days. I believe that it is still available, but it will cost you more money. Contact your dealer if you are interested in this refrigerant. R134a can be found at almost any store. I think even Walmart sells it.

NEVER DUMP REFRIGERANT INTO THE ATMOSPHERE! You can be fined BIG TIME for this. Find a local shop that works with AC systems to pull the refrigerant. Some shops will even do this for free to keep people from releasing the refrigerant into the atmosphere. When you are converting R12 to R134a, you will want to have this done. The two refrigerants are not interchangeable, so do not mix them. You can never empty all the refrigerant just by pulling a line off. You can refill or convert refrigerant for less then $50. A typical recharge will only cost you about $20 (includes adaptor hoses) the first time and about $7 every time after that. Some shops will charge up to $180 for this procedure, so do it yourself and save right off the bat.

Be careful when working with the AC system. Refrigerant is dangerous and the AC lines can get very hot. If the outside air temperature is 70 degrees, the AC lines will be 170 degrees. If the outside temperature is 50 degrees, the AC lines will be about 150 degrees. Get it? All I did was add 100 degrees to the outside air temperature.

Hopefully that will make you understand your air conditioning system better. It is quite simple and easy to repair. Hmmm, maybe it wasn’t worth tearing all that “stuff” out to save weight…


If you have anymore questions, PM me or post up. Thanks

 

[Defiant]

Good post

Originally posted by DSMRevolution
Evaporator - This converts liquid to a gas vapor. The liquid enters as a low pressure liquid and exits as a low pressure gas.

The liquid refrigerant boils, just like water on a stove. And like water, it needs heat to do it. The evaporator is the "burner", and its heat source is the air around it, from the passenger compartment. As the air is moved through the evaporator fins, its heat (and moisture) is sucked out, leaving you with cold air on the other side.

NEVER DUMP REFRIGERANT INTO THE ATMOSPHERE! You can be fined BIG TIME for this. Find a local shop that works with AC systems to pull the refrigerant. Some shops will even do this for free to keep people from releasing the refrigerant into the atmosphere.

Heh, they do it for "free" because refrigerant -especially R-12 is like liquid gold. It doesn't wear out, any they can pull they can re-use.

When you are converting R12 to R134a, you will want to have this done. The two refrigerants are not interchangeable, so do not mix them. You can never empty all the refrigerant just by pulling a line off. You can refill or convert refrigerant for less then $50.

There are also R-12 replacements that are more compatible and more efficient than 134A- and cheaper.

More good, simple information:

http://www.allpar.com/eek/ac.html

 

[Zex4g63]

Good post!

Originally posted by Defiant
There are also R-12 replacements that are more compatible and more efficient than 134A- and cheaper.

You can use any compressable gas. But I don't recomend propane or butane

 

[DSMRevolution]

Defiant - Awesome! Thanks for throwing in some extras. That just makes this thread even better. I wasn't aware that R12 could be reused. That’s interesting. I was always told it was to keep you from dumping it.



Also everybody be aware that liquid can not compress. Another reason for the evaporator to be before the compressor. The vapor "liquid" is what compresses. Most know this, but some do not.

 

[Defiant]

Originally posted by Zex4g63

You can use any compressable gas. But I don't recomend propane or butane

As it turns out, there are hybrids using light gasses such as propane and butane available. The common fear of them is their flammability; however, both R-12 and 134a, once they have their lubricating oils mixed in with them, are about equally flammable to propane or butane.... and, when burned (4000°) break down into phosgene gas. Which would rapidly remove any concern about skin burns, or anything else.
None are as flammable as the ten gallons of gasoline you have in your tail.

 

[DSMRevolution]

Oh, and be careful when using another form of refrigerant besides R12 or R134a. Lets say that you are using Freeze 12 and you are on a trip to Texas with 100 degree plus weather. Your AC breaks down so you decide to pull into the nearest service station. Well guess what, you are out of luck. You need to find a service station that actually will service Freeze 12 since it it a whole different story then R12 or 134a. Different machines are required. In most cases, stick with R12 or 134a.

Be careful when working with the AC system. Refrigerant is dangerous and the AC lines can get very hot. If the outside air temperature is 70 degrees, the AC lines will be 170 degrees. If the outside temperature is 50 degrees, the AC lines will be about 150 degrees. Get it? All I did was add 100 degrees to the outside air temperature.

Hahaha, I meant that the ac lines will have 170 pounds of pressure, not be hot. Sorry for the mistake. It will have high pressure insted of being hot.

 

[Sotarts]

As far as I know, the low-pressure (fill valve) is behind the engine block, right by the side of the block (between engine and firewall). Closer to the left of the car, near the corner of the block. Deep in there. That's on my 1g tubo. Am I right?

 

[Defiant]

Yes, or the factory book shows it being on the compressor. They did a fine job of hiding it. Same on the 2G, it's way the hell down in there. About 2" past where a recharge hose will reach.