Saturday, June 28, 2008

Handyman How To - Replace a A/C Condenser

It’s Tampa Bay’s handyman here again. In this lesson I will be explaining how to replace an A/C condensing unit for your house, apartment or condo, which is outside. The air handler is inside and I will explain how to do this in the next lesson. First thing you should be aware of before you attempt to do this I am assuming that you have your HVAC certification and have made repairs on air conditioners before. You should also be skilled in sweating copper pipes together, if you can sweat copper pipes and have a little common sense with hooking up electrical and handling Freon then replacing an air conditioner condenser is very simple.

Removing the old condenser

First step we have to take is to recover the refrigerant from the old air conditioner condenser. To do this you will need a recovering tank and possibly a recovery machine to speed up the process. DO NOT just vent the old refrigerant into the atmosphere, if you do and are caught you will lose your HVAC certification and will be fined thousands of dollars. While the old refrigerant is recovering into the tank the next step is to undue all the electric on the air conditioner condenser.
Before you start untying wires on the air conditioner MAKE SURE THAT THE POWER IS OFF ! You can check this by using a volt meter. There should be two 24 volt wires, two 120 volt wires connect to the bottom of the contactor, and a ground wire. Now once all of that is disconnected and all of the refrigerant is recovered you can start cutting the copper on the air conditioner condenser. To do this you will need a pipe cutting tool. Once cut it is recommended to sand the copper ends as best as you can to make it easier to sweat the copper onto the new air conditioner condenser. Now remove the old unit. I wouldn’t just trash it either I would scrap it at a junk yard, quick 20 bucks or so for the copper inside the coils.
If you purchased a brand new air conditioner condenser then it should be pre-filled with Freon. Most of the house air conditioners today use R-22, in 2010 this will change though.

Installing the Air Conditioner Condensing Unit

Okay this is what I personally do when I install an air conditioner condenser. The first thing I do is remove the caps from the high and low side inlets and remove the valve cores, I do this because you are going to be holding a torch very close to the valve cores and sometimes they will get so hot they will bend and will not be any good any more. You may need some extra copper piping to make a good connect it to the high and low side inlet. You want to make sure you have a good connection at the low and high side inlets you can do this by having copper fittings that will join the copper piping together.

Next step is to sweat the copper lines together with a torch and solder. To get a good idea on how to do this just google “sweat copper” and a bunch of tutorials will explain and show you how to do it. Now you got a good connection on the copper pipes, check it closely with an inspection mirror, if you don’t see any holes then you should be good to go but we will find out if there is a leak or not when we are vacuuming out the lines. Have a wet rag handy to cool off the copper lines. Next thing I would do is insert the valve cores back into the high and low side inlet of the air conditioner condenser.

Hook up you’re A/C gages to the low side of the air conditioner condenser, open the valve on your gages to the low side, the middle hose on the gages should go to a vacuum pump, turn the pump on and open the valve on the pump, your low side gage should eventually read about 30” suction or ‘mercury’, once it does hit 30” close the low side on the gages, if the gage stays at 30” than you don’t have a leak, if it drops then you have a leak and need to find it with some type of leak detector, you will probably have to re-solder the leaky connection.

Ok so if you have no leaks open the low side on the gages back up, let the low vacuum pump out all the air and gases and non-condensable’s out of the copper lines for about one hour. While this is going on you can start hooking up your electric. Hook it up the same way you unhooked it from the old condensing unit. Two120 volt wires to the contactor, and two 24volt wires together. Put the panel back on. Once you have all the electric hooked up and vacuumed out the copper lines you can shut the pump off. Then grab the correct sized Allen Wrench and open the King Valves on both the low and high side of the Condenser letting all the Freon flow through the copper lines to the Air Handler. Turn on the air conditioner from the thermostat. Hook up your gages and test for correct pressure. That’s it, now your summer days will be cool with your brand new air conditioner.

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