Recharging the air conditioning is one of the final procedures you must perform after replacing the car's heater core. Learn to recharge the air conditioning properly from a certified mechanic in this free automotive video.
Here we're demonstrating how to change a heater core on a late model Ford Explorer or Mercury Mountaineer. In this step we're going to demonstrate the proper service procedure to recharge your vehicle's air conditioning after your heater core replacement. The first thing we're going to do is step back inside the passenger compartment of the vehicle and fire up the engine and turn the air conditioning on to "maximum cool". Alright, we have the AC set to maximum cool, which on this vehicle, is 60 degrees. We're going to go ahead and attach our charging kit to the low side, right here. Now the low side is going to be in between the evaporator and the compressor. I'm going to take and unscrew the cap, just like so. Now you're not going to want to lose this cap, so either take and put it in your pocket or in your tray. Now this is not metal so it won't be magnetized. Once you have the cap off, you can take and hook up your charging line. You're going to do that by retracting this device here, as you can see right there. You're going to retract it, slip it on, and push it down into place, give it a tug to make sure it's on there correctly. We are now going to take and open up the valve and you'll see the gauge begin to move, and there you go. Now the compressor is going to engage and disengage and begin drawing in refrigerant from our can. You're going to want to agitate your can like so, working it back and forth. There is a label underneath the hood which is going to indicate the appropriate amount of refrigerant to install in the vehicle. Now this, here, is a 12 ounce can, and I have a 12 ounce can here, that will give me 1 3/4 pounds. I want to indicate that label to you, and it's going to be right over here, right here, this is your air conditioning label. As you can see, that is how much refrigerant we are supposed to put in, 1 lb., 14 oz., so just a little bit over 1 3/4 pounds. You're going to use R-134a, and it's the only stuff that's available really any more from your automotive parts store. Any other kind of refrigerants, the fittings will not attach, so it's pretty much impossible to get that messed up. You're going to continue agitating until the entire contents of this can has been drawn in. From there you're going to take and switch over your cans and we'll get into that as soon as this one's empty. It'll take 15 to 20 minutes to fully drain a can. Alright, once your can is completely empty, and I mean completely, you can take and unscrew your gauge. Now always point it away from yourself, there may be some residual refrigerant left inside the can, just like so. I'm going to take and dispose of this, just throw it away in your regular trash, there's nothing special you have to do with this. I'm going to show you the procedure for changing your charge canisters. I have another charge can here, and as you see it's sealed up, it's got some metal on there. There is a spike valve inside here that, when we screw the gauge down, will pierce that and open it up to the system. You're going to want to make sure that your gauge is all the way unscrewed before you screw this down and inadvertently pierce the canister. I'm just going to go ahead and start it on there and thread it down until it's tight. Now there's no need to over-tighten these or force these, just hand tight like that. From there, we're going to go ahead and pierce the valve. You'll notice that once we make our pierce, the pressure gauge will jump up, right there. We have now opened it up to the system, we can take and connect our charging line in the same manner as we did for the initial can. Just take and pull the quick connect back and slip it down into place, right there. You want to make sure that the locking ring has snapped down into position, and that it's on there tight. From here the compressor is going to take and draw in refrigerant, you're going to want to take and agitate the can, and let it draw in the whole contents. You can see when the compressor engages, how it's drawing from the can. It takes approximately fifteen minutes to drain a can. You'll notice the can will get real cold as it's drawing it, that refrigerant inside here is actually evaporating and coming out in a gas form into the AC system. You're going to continue draining and using cans until you've reached the appropriate poundage for the vehicle. Now if you have an odd number, if it's not in increments of twelve, it's best to leave it slightly undercharged than to overcharge the system. That is the proper service procedure for recharging your vehicle's air conditioning after your heater core service.