I long time ago I read a post that explained how to test the AC compresor. I have plenty of presure in the system, but the AC compresor doesn't kick in. How do I test to see if the clutch is frozen?

I tried searching for the post, but came up empty handed.

It's getting hot! Help!!!

 

With mine, I was able to locate the pressure senative switch. I rigged it to "activate" the compressor. The compressor turned over. I felt that was good sign.
I rebuilt the system.
Put in R-12
While driving the old compressor failed & seized the belt. Happened to Wife while she was driving. Siad she heard the squeeling & saw the smoke rising.
Buy a new rebuilt compressor.
Take out the guess work & also eventual failure while driving.
I paid $150 from Pep Boys, a good price, too.
Make sure Orifice is replaced, too. Even IF ya buy a new rebuilt one, make sure the Orifice is replaced. It's cheap like $15 or less.
Yeah you are toasting up there.
LA was cooler but recently was very very toasty.
I recently blew my radiator and the cooling system is better now. Hello Summer!

 

Ked, your one bad experience just doesn't justify advising people to buy a $150 part they don't neccessarily need

Bitchin, grab a multimeter and start testing. Start with resistance between the two pins of the low-side pressure switch (electrical component built into the accumulator canister... big silver thing near your EGR valve), then high-side pressure switch (small sensor-size switch on the back of the compressor). Both should read near-zero ohms.

Next, start car, turn on A/C, and let idle while testing voltage along the system. Low-side pressure switch connector, high-side pressure switch connector, and finally the connector at the compressor clutch itself. If you end up with more than 12.5v at the compressor clutch and it isn't engaging, the clutch solenoid is fried. If you end up with 10-12.0 volts at the clutch, try jumping the clutch with actual battery voltage before declaring it dead. I've found compressor clutches are extremely picky. Due to voltage drops, mine is now relay actuated.. relays are far less sensitive than that clutch.

 

Cool. I will test all of the voltages. This is a compresor from the scrap yard, but was working fine all of last summer. My original one was leaking like a sive. As I was charging the system you could see the r-134a spraying out of the seems of the sompresor. It was agravating, but was pretty funny at the same time.

If it is dead $150 isn't that bad. I was looking at prices for brand new ones and dam near popped a vain in my brain. I couldn't belive the prices!! any ware from $450 - $700.

I'm home early from work today so i will actually have time test it before the weekend. Had my consultation for back surgery today. Reduced pain is near!!!!

 

It wasn't just my bad experence that lead me to say go get a new rebuilt one.
When they ain't used for LONG TIME, the seals dry up and soon leak to point of seizing. And that activity of seizing/leaking happens after the system has been recharged. Thus all previous effort for making your AC system operate is for naught.
And at $150-ish for a rebuilt after one does all the "other" work, it's one of those might as well drop rest of those funds.
Since I got my rebuilt compressor 3 years ago & have used it often, I've had no other problems besides "excessive vibrations" which is due to the 1985 year not "including" another back brace bracket that I've seen later years having.
Yeah phone around for prices or seek out a rebuilder. Or give a shout I MAY be able to some help from LA area, BUT, remember there's shipping up north.
Just make sure that orifice is changed. I understood (after mine seized) that's the AC system "filter" to keep out the nasties that helped kill my previous compressor.
Follow the hard lines for a pressure sensor to "trigger" to activate the current compressor. That's how I found out my wires were still good, but system low on freon.

 

As a side note, change the orifice tube anyway-they plug up with
dookie rather easily, and they are way cheap. Do yourself a solid
and buy an automatic adjusting orifice tube, 4-Seasons PN#38902.
This little device that costs less than $20 will drop your temp by 10
to 15 degrees IMOE!

 

That adjusting one sounds cool. it gets well over 100 around these parts. so cooler is better!!

Well I have some progress. Part of my problem looks like a lose wire. After pulling all of the conectors off to check the ohms all checked out fine. reconected every thing and started car gave a few minutes to idle and kicked the ac on high and the clutch started to cycle as if it were low on freon. popped my gauge on it and it the neddle was in the Yellow at about 55PSI. When the compresor would kick in it would drop to all most zero. So I decided to open the can up and add some. I put about half the can in and the neddle would go up to 75 PSI and back down to 15 or 20 PSI when the compresor would spin. 75PSI is just inside of the red zone on the gauge.

Now I am not an expert when it comes to ac systems. at what point should I stop adding r-134a? Thats how the seals were blown out on my first compresor too much was added and fortunetly the seals gave out before any thing bad happened.

Right now I am just trying to get through the next 1 or 2 paydays with out backing my brain ( wait that all ready happened ). If shows it's self to be un reliable at that time I will replace the compresor and orifice tube.

 

In all honesty, it was probably my lack of changing the Orfice tube that caused my other compressor to seize.
And a $10 or so, to make sure the AC line gook is gonna be gone as ya try to cycle what is there now thru the current compressor, it's cheap insurance.
I do not know what is the spec for AC, YET have you tried "reading the answer" at a Pep Boys in their repair books?
(AH-CHOO, Opps opened to the AC repair section, might as well read the answers!)
Yeah that connector does seem stretched to reach the compressor.

 

Same thing happened to me....except I wasn't driving, I was still in the driveway.

 

Well I can't keep the compresor spinning it keeps cycling as if it were low, but I don't want to over fill it. Does any one know what PSI it should be, and witch reading to go by, when the compressor is not spining or the lower PSI reading when it does spin?