AC Compressor engage

[Evaddave 87gn]

I discharged the system when I istalled the motor a couple years ago, so I wanted to charge it. I used one of the vacuum pumps from Harbor Freight ($17...worked great) and evacuated the system. I hooked the gauges up and dropped in 2 cans, took the system up to 50 PSI (low side). I thought the compressor would click on but no go. I dropped in another .25 of a can the system climbed to 65. still nothing. I jumped the low pressure switch...nothing. I verified power to LPS ...good....I checked the relay and I had power to the pink and blk but thats all. (Point of note. I have the bypass for fan from caspers and I no longer use the factory fan I have the Ramchagers dual with kit from Caspers and the field fix for alternator also). I checked the high pressure switch and I have power to the center wire. I have no power to the plug on the front of the compressor. I unplugged the other (round) terminal and no power, I jumped the plug no change.

I sent power directly to the front of the compressor and grounded the other side, compressor turned on low side pulled down to 20 psi high side rose to 150 ish.

So I'm still stuck, no power getting to the compressor. Any ideas?

 

[Evaddave 87gn]

Got it!

 

[TLIMITED]

What was it?

 

[Evaddave 87gn]

What was it?

I found the wire diagram on vortex's site. The blue wire on the LPS activates the AC relay. So it looks like the blue wire is broken between the LPS and the relay. I jumped a wire between the two and the compressor kicked right on.

 

[Antbankstwo3]

A lil' off topic, but got a question? >>> What vacuum did you use from Harbor Freight to evacuate the system? Does it pull any existing R12 in container. Im pretty sure my system is very low or near empty. I wanted to replace the orifice and drier, but I'm not sure if I can just open it up and do it without vacuuming anything out first. Its not blowing cold anymore. A couple months ago when I got it was a lil' cool, but not much. So I'm thinking it needs recharged (I don't know what the previous owner did either). Then, once the system is open, do you have to vacuum it back down to recharge it? This is my first time working on the AC, so just wanted to make sure I do it correctly.

 

[johnl455]

If you open it, you need to pull a vacuum to boil off water and remove all the air. If there is still some positive charge, AND it was a clean charge before, AND you know what type it is, then you can just add more of same. I stay with R12 so I have never tryed 134a in a R12 system. I know it is less efficient and for best results you undercharge the amount compared to R12. Also you should flush and change to the PAG oil for 134a as the mineral oil from the factory for R12 is not compatable. If they mix it's similar to motor oil and antifreeze mixing, like a month old McDonalds shake.

 

[Antbankstwo3]

If you open it, you need to pull a vacuum to boil off water and remove all the air. If there is still some positive charge, AND it was a clean charge before, AND you know what type it is, then you can just add more of same. I stay with R12 so I have never tryed 134a in a R12 system. I know it is less efficient and for best results you undercharge the amount compared to R12. Also you should flush and change to the PAG oil for 134a as the mineral oil from the factory for R12 is not compatable. If they mix it's similar to motor oil and antifreeze mixing, like a month old McDonalds shake.

Thank u for that! Well, I just purchased the car a few months ago. I didn't really realize the Compressor wouldnt engage if the pressure is low. Finally, after I started to drive the care more it work for a bit. Blew somewhat cool. But then stopped again.The car sat for quite some time. I don't think it's ever been recharged. So I'm tempted to jus leave it alone & try to charge it & see what happens. In jus did that with my '71 Skylark. Luckily all was well even after several years of not charging it & not using the AC