rusty1 Posted July 6, 2014 Share Posted July 6, 2014 AC compressor is not starting, so taking adnantage of Advance Auto's 20% off special, bought a manifold gauge set, o-ring set, can of 134a with dye, and can tap. Hooking up the gauges, engine off , 5 psi. low side, 0 high. Same with engine running. I'm considering just adding enough of the 134a to start the compressor, and looking for leaks. The question is: should the compressor be on with 5 psi? And if not , at what pressure will it start? Once the leak is found . I will have the system puged, then vac it and recharge. I had it serviced two summers ago, and last summer it didnt run - so I figure the leak should be fixed rather just recharging. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted July 6, 2014 Share Posted July 6, 2014 the o-rings where the lines meet the compressor are likely leak points. as well as where the lines meet the condenser in front of the radiator. i suggest you get the o-rings from the dealer. they will cost a little more, but they will fit and not leak. i would replace them before you charge the system your self, and then drive it until it does not cool. you may get through the summer without paying the pros. and if it is not the o-rings you have only lost about $10. Quote Link to comment Share on other sites More sharing options...
rusty1 Posted July 6, 2014 Author Share Posted July 6, 2014 (edited) My intent was that if I found 0 psi high and low I would look at the o-rings and replace them as necessary (brittle, deformed etc). The vac down the sysytem and see if it held. With 5 psi on the low side, some refrigerant remains in the system, and I should have it properly recovered at a shop. So adding enough refrigerant to engage the compressor and show where the leaks are seems to me to be a good procedure , although I will lose the added 134a to the recovery process. I should add that I am also working on a 2003 GMC Safari with 0 psi high/low so I plan on using some of the dyed 134a on that. Edited July 6, 2014 by rusty1 Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted July 7, 2014 Share Posted July 7, 2014 (edited) 5 psi is very little refigerant. Normal system pressure wih engine off is around 90-110psi. Check the bottom corners of the condenser for wet/dark appearance or oily crud buildup. This is a common leak point on the older Legacys. Same with the o-rings on top of the compressor. If you have the system open the compressor o-rings only take a minute to replace and are good measure for preventing future leaks at the compressor. Edited July 7, 2014 by Fairtax4me Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted July 7, 2014 Share Posted July 7, 2014 Check for a leak on the aluminum tubing that runs from the bottom of the condenser up to the drier. I lost all refrigerant to a pin hole leak that developed on the tubing near the condenser. I replaced the tubing, added new O rings, and I am back in the cold. Quote Link to comment Share on other sites More sharing options...
rusty1 Posted July 7, 2014 Author Share Posted July 7, 2014 So I hooked up the manifold gauges to it and tried to introduce some dyed 134a into it. Nothing happened. Toko the gauges over to the Safari van, fired it up , and it took the better part of the can, its compressor started and I shut down the valves and went back to the Legacy. This time the Legacy took the rest of the can, its compressor started and cool air was blowing out the vents. Had 100 psi high, 40 low. Started looking for leaks in the usual pleaces - nothing showed up right away. Figure I would run it for a day or two and watch for leaks. Shut down the engine, closed the manifold gauge valves and the can tap valve, disconnected the high side, disconnected the low side and WOOOSH - a fine yellow mist started spewing out of the shrader valve as I frantically tried to cap it. Valve core kit and removal tool have been ordered. Lesson learned. Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted July 7, 2014 Share Posted July 7, 2014 So I hooked up the manifold gauges to it and tried to introduce some dyed 134a into it. Nothing happened. Toko the gauges over to the Safari van, fired it up , and it took the better part of the can, its compressor started and I shut down the valves and went back to the Legacy. This time the Legacy took the rest of the can, its compressor started and cool air was blowing out the vents. Had 100 psi high, 40 low. Started looking for leaks in the usual pleaces - nothing showed up right away. Figure I would run it for a day or two and watch for leaks. Shut down the engine, closed the manifold gauge valves and the can tap valve, disconnected the high side, disconnected the low side and WOOOSH - a fine yellow mist started spewing out of the shrader valve as I frantically tried to cap it. Valve core kit and removal tool have been ordered. Lesson learned. A schrader valve core tool is handy to have. I have one, and have used it many times. Sometimes, the schrader valve just needs to be tightened, not removed and replaced. Hmmmmmmmmmm. also possible schrader valve spring may have wrongly stayed depressed, when hose was removed, hence the WOOSH discharge. Yea, the core insert may indeed need to be replaced. Sounds like you were low on 134a, so compressor won't turn on, until refrigerant is added. The dye works pretty good, also applying soap suds on suspected areas can help find leaks. When you see bubbles form from around the suds, you know you have found a leak. Legacy needs two cans of 134a to be filled from total discharge. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted July 7, 2014 Share Posted July 7, 2014 Sometimes with the first can you have to manually jump the compressor to get it to take the rest of the can. The valves can get stuck occasionally when removing the manifold hoses. Keep a small screwdriver handy to pop the core up and down a few times with. That usually gets them to seat. Quote Link to comment Share on other sites More sharing options...
virginiaham Posted July 8, 2014 Share Posted July 8, 2014 i believe a legacy takes just under 2-Lbs of refrigerant, which is about two 12-oz cans. during normal operation, the low side pressure should be 20-45 psi and high side around 150 psi but could be as much as 250 psi depending on the outside temp. when i perform A/C services at work (i'm a mechanic) i almost always replace the schrader valves. Also, the Low-pressure cut out switch will cause the compressor to disengage below 10 psi on the low side to protect the compressor. If you have a vacuum pump, it is best to pull a vacuum on the system for at least ten minutes before charging, both to verify the integrity of the system, but also because its easire to charge a system that is under a vacuum that one that has 5 psi in it because the refrigerant will actually be "sucked" in. Quote Link to comment Share on other sites More sharing options...
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