Greasy dirt on inside of Hood above Alt./AC Compressor???

[Rob]

I'm catching on to this one a little late and apologize.

I'd like to remind everyone, insulting one another is not constructive and counter-productive to why I built these forums in the first place - for the exchange of information and comraderie.

If you don't agree with someone, fine, state your views, your reasons for disagreeing, and drop it. In a nutshell, lets all try to get along here and help one another out rather than insult one another.

Now, out of curiosity, has anyone checked to see if there is any type of service bulletins out that may relate to this problem?

 

[ErnieN85]

Rob, It's detailed in the Helm's manual for the 1985 Corvette. I don't have manuals for other years so I can't say about more than That.

 

[Eagle85C4]

GIVE IT UP!!!!!

There is no seal on the car that is supposed to leak on purpose. The clutch is a dry clutch....no oil is supposed to be on there. If there is you have a problem. If there is any type of leak on the a/c system you have a problem. I have been repairing a/c systems from cars to 250 ton systems on top of buildings for over 20 years, I have been certified by the EPA for many years. Talk to any a/c shop they will tell you the same thing. I do not know where you got that info but it is wrong.

If your compressor is leaking oil it is also leaking freon or whatever you have in there PERIOD. And just because someone makes a shield to cover it up does not fix the underlying problem...you have a leak. Legally you have to fix it as well.You are in violation of the Clean Air Act for leaking a/c coolant into the atmosphere for which you can be fined 25,000.00....and I can provide you with the documentation to prove all of this.

And just because you read the info from some other then factory manual or off the shelf book does not make it so....try reading the federal regulations regarding freon....try EPA section 609 at www.qwik.com
I am done with this...I am tired of trying to inform you of the truth and not getting through to you. Maybe when the EPA knocks on your door and serves the warrant you will believe...Montoursville,Pa is it?

 

[Rob]

Eagle,

Calm yourself. Service Manuals that are supplied by Helm come from GM. Gordon Killebrew who used to work at the original Corvette Action Center wrote a lot of the service manuals for the C4 generation.

I'm not saying you're wrong, and I'm not saying you're right. However, I would ask you this: if your belief is true, then why would a company like MidAmerica manufacture an item to prevent oil splatter and mask something that could be environmentally harmful?

 

[Eagle85C4]

Mr. Loszewski,

Sir, if you have an understanding of the basic economic law of supply and demand it is easy to understand why they can sell such an item. If you have not had to have your a/c system updated lately you know it is quite pricy to fix. The shield provides a means to cover up the leaking which does not fix the underlying problem in the first place. If it is leaking fix it...not cover it up.
Remember the pet rock? How many bought that? The guy made 38 million, selling a plexiglass piece to keep the oil off the hood of our corvette's would be easy...wish I had thought of it...I would be laughing all the way to the bank...I would be at every vette get together I could find with a suitcase full.

Further more, SIR, I respect and understand your position, if I were to send you a detailed explaination of the problem and what it represents, what causes it and how to fix it, you could at your discretion place it somewhere on the site so others could see why it is imperitive to fix any oil leak on an a/c system before it costs you bunches or causes a fire.

Thank you for your time.

Raymond Belyea
Senior Engineer
Tele-source Industries

 

[Rob]

Ray,

If the information you have relates to automotive AC systems, then, yes, I would be willing to add it to our Knowledgebase as I think it would be helpful to many owners.

As a small aside I found the following on the web which I thought was a good description of how automotive AC systems work:

Air Conditioning Systems
by Chris Bede

Today, as we drive our automobiles, a great many of us, can enjoy the same comfort levels that we are accustomed to at home and at work. With the push of a button or the slide of a lever, we make the seamless transition from heating to cooling and back again without ever wondering how this change occurs. That is, unless something goes awry.

Since the advent of the automotive air conditioning system in the 1940's, many things have undergone extensive change. Improvements, such as computerized automatic temperature control (which allow you to set the desired temperature and have the system adjust automatically) and improvements to overall durability, have added complexity to today's modern air conditioning system. Unfortunately, the days of "do-it-yourself" repair to these systems, is almost a thing of the past.

To add to the complications, we now have tough environmental regulations that govern the very simplest of tasks, such as recharging the system with refrigerant R12 commonly referred to as Freon® (Freon is the trade name for the refrigerant R-12, that was manufactured by DuPont). Extensive scientific studies have proven the damaging effects of this refrigerant to our ozone layer, and its manufacture has been banned by the U.S. and many other countries that have joined together to sign the Montreal Protocol, a landmark agreement that was introduced in the 1980's to limit the production and use of chemicals known to deplete the ozone layer.

Now more than ever, your auto mechanic is at the mercy of this new environmental legislation. Not only is he required to be certified to purchase refrigerant and repair your air conditioner, his shop must also incur the cost of purchasing expensive dedicated equipment that insures the capture of these ozone depleting chemicals, should the system be opened up for repair. Simply put, if your mechanic has to spend more to repair your vehicle - he will have to charge you more. Basic knowledge of your air conditioning system is important, as this will allow you to make a more informed decision on your repair options.

Should a major problem arise from your air conditioner, you may encounter new terminology. Words like "retrofit" and "alternative refrigerant" are now in your mechanics glossary. You may be given an option of "retrofitting", as opposed to merely repairing and recharging with Freon. Retrofitting involves making the necessary changes to your system, which will allow it to use the new industry accepted, "environmentally friendly" refrigerant, R-134a. This new refrigerant has a higher operating pressure, therefore, your system, dependant on age, may require larger or more robust parts to counter its inherent high pressure characteristics. This, in some cases, will add significantly to the final cost of the repair. And if not performed properly, may reduce cooling efficiency which equates to higher operating costs and reduced comfort.

Vehicles are found to have primarily three different types of air conditioning systems. While each of the three types differ, the concept and design are very similar to one another. The most common components which make up these automotive systems are the following:


COMPRESSOR
Commonly referred to as the heart of the system, the compressor is a belt driven pump that is fastened to the engine. It is responsible for compressing and transferring refrigerant gas.

The A/C system is split into two sides, a high pressure side and a low pressure side; defined as discharge and suction. Since the compressor is basically a pump, it must have an intake side and a discharge side. The intake, or suction side, draws in refrigerant gas from the outlet of the evaporator. In some cases it does this via the accumulator.

Once the refrigerant is drawn into the suction side, it is compressed and sent to the condenser, where it can then transfer the heat that is absorbed from the inside of the vehicle.

CONDENSER
This is the area in which heat dissipation occurs. The condenser, in many cases, will have much the same appearance as the radiator in you car as the two have very similar functions. The condenser is designed to radiate heat. Its location is usually in front of the radiator, but in some cases, due to aerodynamic improvements to the body of a vehicle, its location may differ. Condensers must have good air flow anytime the system is in operation. On rear wheel drive vehicles, this is usually accomplished by taking advantage of your existing engine's cooling fan. On front wheel drive vehicles, condenser air flow is supplemented with an electric cooling fan(s).

As hot compressed gasses are introduced into the top of the condenser, they are cooled off. As the gas cools, it condenses and exits the bottom of the condenser as a high pressure liquid.

EVAPORATOR
Located inside the vehicle, the evaporator serves as the heat absorption component. The evaporator provides several functions. Its primary duty is to remove heat from the inside of your vehicle. A secondary benefit is dehumidification. As warmer air travels through the aluminum fins of the cooler evaporator coil, the moisture contained in the air condenses on its surface. Dust and pollen passing through stick to its wet surfaces and drain off to the outside. On humid days you may have seen this as water dripping from the bottom of your vehicle. Rest assured this is perfectly normal.

The ideal temperature of the evaporator is 32° Fahrenheit or 0° Celsius. Refrigerant enters the bottom of the evaporator as a low pressure liquid. The warm air passing through the evaporator fins causes the refrigerant to boil (refrigerants have very low boiling points). As the refrigerant begins to boil, it can absorb large amounts of heat. This heat is then carried off with the refrigerant to the outside of the vehicle. Several other components work in conjunction with the evaporator. As mentioned above, the ideal temperature for an evaporator coil is 32° F. Temperature and pressure regulating devices must be used to control its temperature. While there are many variations of devices used, their main functions are the same; keeping pressure in the evaporator low and keeping the evaporator from freezing; A frozen evaporator coil will not absorb as much heat.

PRESSURE REGULATING DEVICES
Controlling the evaporator temperature can be accomplished by controlling refrigerant pressure and flow into the evaporator. Many variations of pressure regulators have been introduced since the 1940's. Listed below, are the most commonly found.

ORIFICE TUBE
The orifice tube, probably the most commonly used, can be found in most GM and Ford models. It is located in the inlet tube of the evaporator, or in the liquid line, somewhere between the outlet of the condenser and the inlet of the evaporator. This point can be found in a properly functioning system by locating the area between the outlet of the condenser and the inlet of the evaporator that suddenly makes the change from hot to cold. You should then see small dimples placed in the line that keep the orifice tube from moving. Most of the orifice tubes in use today measure approximately three inches in length and consist of a small brass tube, surrounded by plastic, and covered with a filter screen at each end. It is not uncommon for these tubes to become clogged with small debris. While inexpensive, usually between three to five dollars, the labor to replace one involves recovering the refrigerant, opening the system up, replacing the orifice tube, evacuating and then recharging. With this in mind, it might make sense to install a larger pre filter in front of the orifice tube to minimize the risk of of this problem reoccurring. Some Ford models have a permanently affixed orifice tube in the liquid line. These can be cut out and replaced with a combination filter/orifice assembly.

THERMAL EXPANSION VALVE
Another common refrigerant regulator is the thermal expansion valve, or TXV. Commonly used on import and aftermarket systems. This type of valve can sense both temperature and pressure, and is very efficient at regulating refrigerant flow to the evaporator. Several variations of this valve are commonly found. Another example of a thermal expansion valve is Chrysler's "H block" type. This type of valve is usually located at the firewall, between the evaporator inlet and outlet tubes and the liquid and suction lines. These types of valves, although efficient, have some disadvantages over orifice tube systems. Like orifice tubes these valves can become clogged with debris, but also have small moving parts that may stick and malfunction due to corrosion.

RECEIVER-DRIER
The receiver-drier is used on the high side of systems that use a thermal expansion valve. This type of metering valve requires liquid refrigerant. To ensure that the valve gets liquid refrigerant, a receiver is used. The primary function of the receiver-drier is to separate gas and liquid. The secondary purpose is to remove moisture and filter out dirt. The receiver-drier usually has a sight glass in the top. This sight glass is often used to charge the system. Under normal operating conditions, vapor bubbles should not be visible in the sight glass. The use of the sight glass to charge the system is not recommended in R-134a systems as cloudiness and oil that has separated from the refrigerant can be mistaken for bubbles. This type of mistake can lead to a dangerous overcharged condition. There are variations of receiver-driers and several different desiccant materials are in use. Some of the moisture removing desiccants found within are not compatible with R-134a. The desiccant type is usually identified on a sticker that is affixed to the receiver-drier. Newer receiver-driers use desiccant type XH-7 and are compatible with both R-12 and R-134a refrigerants.

ACCUMULATOR
Accumulators are used on systems that accommodate an orifice tube to meter refrigerants into the evaporator. It is connected directly to the evaporator outlet and stores excess liquid refrigerant. Introduction of liquid refrigerant into a compressor can do serious damage. Compressors are designed to compress gas not liquid. The chief role of the accumulator is to isolate the compressor from any damaging liquid refrigerant. Accumulators, like receiver-driers, also remove debris and moisture from a system. It is a good idea to replace the accumulator each time the system is opened up for major repair and anytime moisture and/or debris is of concern. Moisture is enemy number one for your A/C system. Moisture in a system mixes with refrigerant and forms a corrosive acid. When in doubt, it may be to your advantage to change the Accumulator or receiver in your system. While this may be a temporary discomfort for your wallet, it is of long term benefit to your air conditioning system.

 

[Rob]

Ray, et. al.,

I received the information you sent via email and have added it to our Knowledgebase which you can view here:

http://www.corvetteactioncenter.com/kb/index.php?ownertopic_id=91 Click the box next to Air Conditioning and press the Answer button.

Thanks Ray!

 

[Eagle85C4]

further back up the thread I posted the same article...or at least the link to it.
I have sent you email with the slightly technical article about A/c systems. I think you will find it very informative and that it addresses several issues which we can use. Thank you...

 

[Vettelt193]

Eagle, since you seem to be the expert here, explain to me why Most C4's have the leak, AND almost every vette I have seen with the leak has Cold A/C. You make it seem like the system will blow up in your face if you don't get it fixed immediately... I am now on my 3rd C4 (and my family has had 3 '87s, a '91, 2 '93s, and a '96 as far as C4's go. All but the '96 had the leak), and have put over 100k on C4's with this A/C leak, AND with Ice cold A/C... Don't get me wrong, I know they should NOT leak, but but but... my argument is that most C4's have the leak, and most of them can be driven safely with it. If you are the type that needs everything perfect, fix it, otherwise chances are the A/C will last awhile. I am sure I don't understand A/C systems as well as you do, so is my experience just unusual? How many C4 owners out there have the leak? It may make for an interesting poll

 

[Eagle85C4]

Thank you for asking the right questions...I shall provide an answer...just above Rob provided a link to my addition to the info base. It concerns A/C and you will come to realize why they leak.
The explaination is very good. My 85 does not leak because I did it the right way and used the right "ingredients". Which you can as well once you read the article.
Also the newer cars were changed to 134a and newer oil so the tendency to leak is minimal if the system is kept up with. Read the article and you will understand...follow the instructions for trouble free A/c.

 

[vetsvette]

I had the "gunk" on the underside of my hood. It's painted yellow so it was very noticeable. Turned out to be a leaky water pump and the belt was throwing it on the underside of the hood.
Slow leak+Dexcool+fan belt= "gunk"

 

[trackitman]

Compressor Rebuild Kit?

Does anyone know if there a kit out there to rebuild the compressor? I checked a few online places and couldn't seem to find anything resembling it. I believe I have a leak in the front part of the compressor. After charging the system, when the compressor engages, a fine mist cloud puffs out towards the left front wheel. The charged system cools for a while, then eventually, the compressor becomes dormant and the code on the LED display is 09, low freon. My conclusion is the compressor is the culprit and I am interested in rebuilding it this coming winter.

Many thanks - Just so you know, I've posted two questions on this forum and have received very helpful responses. I hope that as I gain knowledge in the various systems, I can then "give back" to you.

 

[Eagle85C4]

You should check any a/c shops in the area and they should be able to sell you the seal..or get one from GM. The only tools out of the ordinary is a clutch puller available at most parts stores...
Once you get the clutch off just pry old seal off and install new seal, replace clutch. Now take it to a/c store and have them pull a vacuum on the system to see if it will hold ...usually they will pull it down to 30 lbs. for 30 minutes. If it holds then recharge system you should be good...anything more just ask...

 

[trackitman]

Thanks for the Advice - EOM