Another frickin AC thread
 

OK, so my AC doesn't work...no great shocker there. The fans blow, and the AC button lights up but there is nothing cool coming out of the vents.

I hear about leak-down tests, vacuum tests, etc but it is all Greek to me; having said that I am willing to learn.

How can I tell if my condenser is good? I see nothing in the drier window...no bubbles, nothing.

Can someone please tell me a good step by step plan to try and run down what could be wrong?

Thanks in advance!

GHEN

I do enjoy letting owners without AC suffer.

GHEN,

I think you mean your "compressor" and not the condensor.
"No bubbles, nothing" This means your compressor is not pumping freon past the receiver/dryer. The compressor does all the hard work.

Can you tell if the compressor clutch is engaging when you turn on the AC? It should go on and off every 20 seconds or so. You can watch with the hood up.

If you do not see the compressor clutch engage, go to the next step.

First check to see if you can get the compressor clutch to engage the pulley to spin the compressor.
Run a long wire from the battery positive post to the compressor coil wire. This is the only single wire that comes from the compressor and goes to the frame about 18 inches. You will see a connection at this point.

SO, get everything ready under the car, block the wheels, have the compressor coil wire disconnected, start the car, turn on the AC, go under the car, holding the long wire from the battery, touch the short coil wire for a second and see if the clutch engages on the compressor.

IF it does, your compressor coil and clutch work and it should be pumping freon--IF you have any in the AC system

If it does not ---could have a bad coil. Now you may need a rebuilt compressor with clutch and coil.

Look at the compressor front shaft by the coil and pully, Do you see a large area of oil? If you do the front seal is bad and you need a reseal on the compressor.

BUT, IF you see the clutch engage AND no oil slick on the front of the compressor, your compressor should be OK and you are out of freon.

NOW you can decide to take it to a shop or continue...

Go to Harbor freight and buy the automobile AC Guage and line kit. About $50 ( less with couponZ)

Hook it up to your High and Low port and slowly open the valves. Some instructions included.
Do the valve needles move at all?

NOW you can buy a $100-$120 vacuum pump at Harbor Freight at least 2.5cfm, and test to see if your car has a leak. Vacuum for at least an hour and then shut off the vacuum pump and wait an hour to see if it holds a vacuum.

If it does not hold a vacuum, you have a leak. Find the leak. HOW? Put some R134a in the system and listen for a leak. OR you can buy a electronic freon sniffer about $100 and way up.

Fix the leak, reseal the compressor if needed, replace the receiver/dryer, put in AC oil, fill the system with R134a and you have cold AC.

Simple huh?

GL
John

John,

You constantly amaze me with the breadth and depth of your knowledge. Thanks for the wonderful advice.

I'll start where you suggested, thank you!

And yes, I meant compressor, but thanks for clarifying.

WPR,

GHEN

I got my guages at HF cost me 40$ because it was already on sale and i got a 20% off coupon which you can get online just do a search.

The ac vacuum pump was kinda expensive for me and i already had a large compressor so i purchased the kinda that hooks up to the air compressor under 10$

When you pull a vacuum you should get about -30 psi on you're guage or close too it. once you shut off you're low and high side valves it should hold whatever pressure you were able to achive for at least 30 min to 1hr but i check it after 5-10 min bc if it has droped by then you have a huge leak.
there is usualy an dirty oily residue when there is a leak. mine was at the front of the condensor were the 2 lines connect. and there are some cans of r134a that have some UV die in it to help you find a leak with a UV light which works best at night. this is assuming you system is low and you have to recharge it up and you're a/c pump should probly turn on with about 1 can of freon.

i have a linke to a whole 288 page book if you need it. it was very helpfull to me and helps make sense of alot of things

GHEN,

I missed a step.

If the compressor does not engage, the system could be low on freon.

There is a low pressure switch usually next to the receiver/dryer (sight glass).

Pull the wires off the switch------jump the 2 connectors together with a wire.-----does the compressor clutch engage now? If it does, you can try to add some freon. You cannot mix R12 with R1234a.


If the compressor clutch does not engage when you jump the low pressure switch, then try the 12V line from the battery to the coil wire.

GL
John

GEHN,

All the tests for the compressor are for a couple of seconds. Do not run the compressor longer.

Without freon the compressor will burn out.

John