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Need to fix my AC

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Now that I've got my radiator repaired, I need to move on to the next big problem.  It's hot down here in the deep south and my air conditioning system isn't working.  This is something that I'm not experienced with.  It just blows hot air.  How do I diagnose?  Where do I start?



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You will need from Harbor Freight:

Manifold Gauges $60

Small Vacuum Pump $90


You will need from Auto Parts Store:

R134a Can Tap $8


You will need from Walmart:

R134a Refrigerant Cans (3-4each) $5

(You only need two cans but it takes forever once a can gets low... you’ll see what I mean..)


It’ll be $160 but you’ll pay that to someone just to refill your system with refrigerant and check for leaks...


The process isn’t hard either but you’ll have to go to a shop and let them recover any refrigerant left in the system. That’s step one; get the pressure in the AC system at zero.


Then you’ll pull a vacuum for an hour and recharge the system.


That’s it and you just put in exactly the amount listed on a sticker found in your engine bay.


From that point on you’ll be checking to see if it works or not and if not then I’ll tell you how to check different parts of the system with the pressure readings on the gauges.




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Thanks so much.  I'd can swing $160 if it fixes the system.  I'll need more guidance, but before we get there, what if it is the compressor or condenser?  Before I purchase materials to charge the refrigerant, shouldn't I ensure all the components work?  Problem is I don't know how.

Edited by AlabamaDan
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Well you need all that stuff to put a proper charge in the system so you can see what’s going on with it.


I guess you could just get the can tap and a couple cans of refrigerant and charge the system. That way you can see if the compressor will cycle or not.


If the compressor does engage and you still don’t have cold air then you’re going to need the gauges for further diagnosis.


The thing is though, if you don’t put in the correct amount of refrigerant, or if a lot of moisture has gotten in the system then you’re not going to be able to reliably test any of it.


The cheapest option I think is going to be to let a shop evacuate the system and you can put two cans in and see what happens. Unless it is a nice shop they’re just going to vent the system to atmosphere though... I’m not going to tell you to just do that yourself but 9 out of 10 times they just open the system to atmosphere..


So get the system to zero pressure. Then with a can tap that will attach to your low side fitting and put exactly two full cans in. When you are putting the cans in try to run the AC. When the system detects enough pressure then the compressor will kick on and it’ll pull the refrigerant out of the cans a lot better.


This is the type of can tap you’ll need:



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When a friend and I fixed the aircon in his Blazer, we vacuumed the system down with a pump and let it sit for a while to see if air pressure got back in. It didn't, so we added the proper amount of oil and refrigerant with the engine running and it's been blowing cold since.



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You may find that just charging the system will meet your needs for the summer, may even do the trick for a few summers, but ultimately you will need to find and correct the coolant loss in the long term.

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  • 1 year later...

I never did it myself last year, but I did take it to the shop today.  A trusted mechanic.  He said it needs a new compressor.  His estimate $1000+ to repair.  Any ideas from my community?


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Tell him he can pound sand.
Have you ever been in a front end collision or see any evidence of such? My 93 originally had a copper radiator but most are now aluminum.
Make sure your condenser and radiator fins are clean and not clogged up. Home depot has some type of coil/fin cleaner for home HVAC units but i do not knoe if it's snake oil to try. Cheap but wouldn't hurt. A gentle stream from the garden hose will work too if you do not have mud clogging it up. Make sure the fins are straight. Take care to bend then straight with a small thin flathead or similar tool.
Stock use to have foam filter guides to "seal" the sides of the condenser and radiator so the fan can efficiently pull air through the fan shroud without air leak. You can use aluminum tape or rubber gasket liner from home depot as a replacement. All this is to ensure maximum efficiency of the stock mechanical fan.

When you press the ac switch and turn on the fan dies the clutch engage? If not check to make sure the single wire plug is hooked up to the compressor. It follows the distributor harness to the side. Plugged and not frayed or broken check to see if you have pressure in the line. If it is too low or too high, the compressor clutch will not engage.

Check to make sure your high and low pressure lines do not have cracks.

Get yourself a recharge kit and follow directions.
When it gets up to pressure the compressor will kick on but if you have air in the lines, it will-over pressurised and the compressor clutch will disengage to prevent an explosion.

The auto parts store has rental vacuum pumps and manifold gauges. Even harbor freight if you want to buy. Use their coupons if you do.

Also keep in mind there is a ratio of oil for so many oz of refrigerant. You do not want to overoil.

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I have a junk yard compressor blowing super cold air in my QX4 that I paid $40 for.. and it’s guaranteed to be in working condition or you can come back and pull another one until you get a good one.


Where exactly are you?

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