I have a 96 blazer in which I just replaced the accumulater. I thought that an o-ring was leaking because it was losing freon, so I replaced it. i vacuumed down the system for about an hour. I went down to about -25 or so. I then shut off the vacuum and the system held the vacuum for about 45 minutes at which time I started to put freon into the system. I jumped the low side to get the compressor to start and after a short while i plugged the low side in and everything went like it was supposed to. I put in the required amount of freon which is about 28oz. Pressure reading were about 40 low and 150 high. I live in MO and it was about 100-102 degrees when I was doing this. I was cooling great and the system seemed to be fine. I shut it off and left it alone. That was yesterday. This afternoon i started the blazer and turned on the air and nothing but hot air. I popped the hood and the compressor wasn't turning. I turned everything off. Put gauges on the system and 5 low and zero high. I can't find any oily residue anywhere. If it held a vacuum how and why did it leak out? The compressor was cycling normal so I don't think any relays are bad but not sure. (also, where are they located) I am puzzled. Any info or thoughts would be greatly appreciated. I think I covered everything. Sorry about the long post.

 

You should have been able to pull a vacuum down to -30inHg. And if you had opened the system, I would have wanted the pump on there for at least a few hours and then left it over night with the valves closed to make sure that it didn't move. 45 minutes just seems like you were rushing it.

Besides that, I would go over the system CSI like with the uv (black) light and amber glasses to see if you can find the source of the leak. If the refrigerant that you put in didn't have dye in it, you will have to put dye in to find the leak.

 

I just might do it again. And not it did not have dye in it. My bad. I used a vacuum pump that was my brother in laws that was used for a suction machine in a hospital. Almost brand new. Might have to use another. Not sure if it could suction that much. I'll just try again. and leave it longer.

 

I've never had a problem with just pulling to 25 in hg with a new accum. To be sure several hours at that works best

That has nothing to do with your problem. Vacuum is one thing.. pressure another.. when it comes to seals and o-rings. One place can fool you is compressor shaft seal

Yet another necessary tool to work on AC is a tank of nitrogen for pressure testing after assembly. Vacuum, then use nitrogen to pressurize system and watch for leakdown. If there is some you can use suds mixture to check joints or spray accessible areas. Suggest childrens bubble blowing solution in spray bottle.

Added: I swapped compressor out on tbird and kept seeing leakdown on nitrogen pressure test. I figured I would have to spend next day tracking the leak. But I pressurized it to 125 lbs and left it. Next day it was 90 lbs and steady. Watched it several hours, jiggled the springlok connections and still stayed steady. Pumped it back down and filled and it's been working fine.

Little ****lers like that are why I discourage opening systems when you dont have to... even having a pro do it.

 

I did use the soapy water method and found nothing. I take it you have to disassemble the compressor to get to the shaft seal? Might have to try the nitrogen also. Thanks

 

Nitrogen is cheap when compared with refrigerant and is also a smaller molecule than the refrigerant so it finds its way through any and all leaks rather quickly. If there is a lot of junk in the system though, it may be necessary to use an R22-Nitrogen leak testing mix to find leaks.

The shaft seal is behind the clutch so you would have to remove the clutch to be able to see the seal.

 

I'll just do some research on the shaft seal. Can you see the shaft seal leak if I spray soapy water around it? Where can I get nitrogen? My brother in law might have some but he lives 3 hrs away

 

Nitrogen can be purchased at most welding/cutting gas supply locations. You don't need a lot, but you will need a tank and the appropriate adapters to connect the tank to the a/c gauge set (depending on the style of tank).

 

Thanks for the info. I wont be able to work on it for a couple of days. Will let all know. And any more info would be great

 

just get the dye, i just found a leak on my ac using a can of freon with dye, I took my 2000 blazer for ac service the charged me $125.00 , they said everything was ok, but after 3 days I got nothig but hot air, I went back , they did everithing again and said it passed the pressure test, 3 ay later I went back and this time they said That the only place were it coul be leaking was at the service valves, I went to the store bought the valves, installed them and wen back to have the sistem refilled, but after a couple days, empty again, so I went to kragen and bought the freon with dye in it and the black light, charged the sistem with the freon and wait until night, and I found out that the freon was leaking at the compressor body since Im in a tight budget and did not wanted to buy another compressor, I went to kragen and bought an universal oring kit and rented the tool to service the compressor, after I got the compressor appart I found that one of the orings(big one arround the compressor's body) was broken and the one that came on the kit I bought was different, now after serching for rebuit kits I m gonna order them on line I think they have them here .Automobile Air Conditioning Parts of Tucson Arizona, Century Auto Air, AC Parts, AC Service and Hoses, www.centuryautoair.com I think is about $10.00 better than paying $300 for another compressor and the rent of the tool at Oreilly's is free