|06/21/2007, 09:02 PM||#1 (permalink)|
HOW TO: Service your A/C System (not dialup friendly)
The purpose of this how-to is to explain to everyone how to properly service their A/C systems. If you are unsure or not confident in your abilities, please DO NOT attempt to service your A/C system yourself. The pressures involved can be dangerous.
First of all, do not attempt to do any work on your A/C system without a proper set of Gauges. This is what I am referring to.
A close-up of the Gauge faces.
These Gauges measure pressure on both the 'Low Side" and the "High Side".
I got mine at Harbor Freight for less than 50 bucks. It was on sale though, I am not sure of their regular price.
The Air Conditioning system on the 3rd Generation Eclipse is a closed-loop thermostatically controlled system. The system contains the following parts.
A Compressor, a Condenser Core, a Receiver/Drier, a Thermostatic Expansion Valve, and an Evaporator Core. This is also the order of refrigerant flow in the system. The system has two "Sides" to it. The "High Side" is from the Compressor to the Expansion Valve. When running the pressure can be over 200 PSI inside and the refrigerant is in a liquid state. Heat is removed from the refrigerant on this side. The "Low Side" is from the Expansion Valve back to the Compressor. The pressure inside is usually between 25 and 40 PSI when running and the refrigerant is in a gaseous state. Heat is absorbed into the refrigerant on this side.
This is a Condenser Core.
It is located between the radiator and power steering cooler.
Hook up the gauges to the service ports.
Once you hook up your gauges with the car off, you should see something like this. If it does not, as in the readings are much lower, unless it is cold outside, there may be a leak in the system.
Both high and low side read the same pressure. That pressure will vary depending on ambient temperature. This is called Static Pressure.
Now start the car and turn on the A/C as follows. Fan to max, temperature all the way cold, and recirculate on. Let the car idle for about 5 minutes. The gauge set should be similar to the following image.
The low side pressure should be between 25 ad 40 PSI and the high side pressure should be at least 150 PSI but not more than 250 PSI. If the low side pressure is higher than 40 PSI and the high side pressure is lower than 150 PSI, suspect a weak compressor or bad expansion valve. If the needles are jumpy, the compressor is failing. If the high side pressure is higher than 250 psi, the system is overcharged. If the high and low pressure are the same, i.e. no change from static, the compressor is completely dead.
Before opening up the A/C system, take the vehicle to a garage and have them evacuate the system of all refrigerant. DO NOT vent the refrigerant in to the atmosphere. R-134a does not damage the Ozone layer like R-12 does, but R-134a is about 100 times more potent of a greenhouse gas than Carbon Dioxide.
Once the system has been evacuated, remove the output hose from the compressor, It is the smaller one. Look inside of it. If metal shavings or flakes can be seen stuck to the walls of the tubing, a replacement Compressor and Condenser Core will be needed. The Receiver/Drier is built in to the Condenser Core and cannot be replaced separately. Do not skimp on the Condenser Core. Failure to replace it after a catastrophic Compressor failure will only destroy the new Compressor. It is also recommended to replace the Expansion Valve, since it may be clogged with debris as well.
If any parts are replaced, be sure to add compressor oil to the new part. Mitsubishi calls for PAG 56, but it is not available except from the dealer, the closest grade is PAG 46. A Compressor holds 100 mL, although sometimes it comes pre-filled, check anyways. A Condenser Core holds about 15 mL of oil.
Recharging the system
Always recharge the system through the Low Side port. Add one 12 oz. can of R-134a back into the system and turn the compressor by hand 10 times clockwise to clear any oil from it. Start the engine and turn on the A/C as follows. Fan to max, temperature all the way cold, and recirculate on. Let the car idle for about 5 minutes. The gauge set should be similar to the following image.
If it does, problem solved.
|06/22/2007, 10:11 AM||#2 (permalink)|
MINI by proxy
Join Date: Mar 2006
Location: Denver, CO
Vehicle: 2007 MINI Cooper S
Thank you for a very detailed and informative write-up.
I'm glad you went more in depth, as we previously had only a basic How-To on recharging your refrigerant. http://www.club3g.com/forum/maintena...ge-your-c.html
I wonder if it was coincidence or a conscious decision, your posting this on the first day of summer!
I expect a number of people are in need of this sort of info, myself included.
I'm sure this thread will end up locked as is the custom with Eclipse Garage threads... for whatever reason. (I suspect it has to do with cutting out clutter/misinformation)
For those of you wanting to know more, Hardline seems more than willing to advise via PM. If you can't reach him, I'll soon have first-hand experience with this process up to an including Replacing Parts, and may be able to help.
I'm also saving these pics to my HD... just in case.
Stay cool, C3G!