York On

York On-Board Air Compressor System (continued):

Compressor Acquisition and Testing. The next step was to obtain a York compressor.   This was one of the more challenging steps in this project. Not only do you have to find the correct compressor, but you also have to make sure it works properly (especially if you get one from a salvage yard like I did). I had three options available to obtain a compressor:

Purchase a new compressor.

After shopping a couple of local Air Conditioner repair shops, I got an average price of about $300 for a brand new York compressor (including the pulley/clutch assembly).

Purchase a refurbished compressor.

A few local auto parts stores quoted me approximately $200 for a refurbished York compressors (including the pulley/clutch assembly).

Purchase a used compressor from a salvage yard.

This is the option I chose. I got a compressor (including the pulley/clutch assembly) for ... are you ready ... 20 bucks! Although, I had to find the appropriate vehicle and remove the compressor myself. Luckily I had the little tool kit that I always carry around with me in the Jeep.

WARNING: If you plan to obtain your compressor from a salvage yard, you may or may not get any type of warranty. Therefore, it's up to you to make sure that you are getting the right compressor, and one that works properly. I was able to check the operation of my compressor before removing it from the vehicle. It would have been a bummer to get the thing out, and then find out it didn't work! Basically, there are two things to check for, using two very simple tests:

Make sure the compressor pumps air!

In order to remove the compressor from the donor vehicle, you will have to either cut the two A/C hoses, or unbolt them from the two manifolds on top of the compressor. Even though the Kilby bracket kit came with new manifolds, I chose to cut the hoses because I wanted both parts of the stock manifold fittings, just in case.

NOTE: If you purchase your compressor from a reputable "Used Parts/Salvage Yard", chances are one of the yard employees will remove the compressor for you. Prior to removing the compressor, they should properly discharge the system and recover the freon. Allowing the freon to escape into the atmosphere is harmful to the environment.

Next, cut or otherwise remove the fan belt(s) that drive the compressor (mine had two belts). The top of the compressor housing should somehow be labeled as to which port is "suction" and which is "discharge". Put your finger over one of the hoses or manifold openings, and turn the inner part of the pulley/clutch assembly with your other hand. After a couple of turns, you should feel the pump either sucking or blowing through that manifold, depending on which hole you covered. Check both, just to be sure.

NOTE: When performing this test, don't turn only the outer pulley by itself, cuz nothing will happen. The compressor pumps air only when the inner part of the pulley/clutch assembly is turning.

Make sure the pulley/clutch assembly properly engages and disengages!

You should see only one electrical wire coming out of the front side of the compressor (it's actually connected to the pulley/clutch assembly). This is the wire that is normally connected to the thermostat as part of the vehicle's A/C system. When the temp gets above what you have set on the climate control, electrical power flows through this wire, activates an electromagnet within the pulley/clutch assembly, which causes the inner part of the assembly to turn along with the outer pulley (which, of course is always turning as long as the engine is running). It's this inner part of the pulley/clutch assembly that actually runs the compressor, which pumps freon through the vehicle's A/C system. For our purposed, however, we will be connecting this wire to a pressure switch which will activate the compressor when the air pressure in the on-board air system drops below a certain level. When the pressure in the system reaches the upper level, the pressure switch turns off the electrical power to the compressor, and the inner part of the pulley/clutch assembly will stop turning.

Okay, now for the simple test to see if it works. First, either cut or unplug the wire on the compressor from the donor vehicle ( I cut the wire on the vehicle side of the plug, so that I would have both parts of the plug to use in my Jeep). Now spin the outer pulley on the compressor. It should turn freely by itself (i.e., the inner part of the pulley/clutch assembly should not be turning with the outer pulley at this time). Now touch the wire (that you disconnected) to a 12-volt power source (the battery in my donor vehicle still had some juice left in it, so I didn't have to worry about grounding the compressor (see note below). You should hear the compressor "click" when you apply power. Turn the outer pulley again (while power is still applied). Now both the inner part of the pulley/clutch assembly as well as the outer pulley should be turning together. Now remove the power source. The compressor should "click" again, and the outer pulley should once again spin freely by itself. That's all there is to it!

NOTE: If you are doing this test after removing the compressor from the donor vehicle, or if you are using a power source other than the donor vehicle's battery, you must "ground" the compressor to your power source. For example, you can connect the compressor wire to your Jeep battery (positive terminal), and a second wire from any part of the compressor housing to any "good ground" on your Jeep, or to your negative battery terminal.

My donor vehicle was a 1977 AMC car (I forget exactly which model). Whoever owned this particular vehicle, had never cleaned his/her engine! Cuz there was at least 20 years of grease and grim build up on this compressor. Here are a couple of shots of the compressor immediately after I got it home. Notice the stock manifolds on the top of the compressor, the hoses that I cut, and the electrical wire to power the clutch.



It took me over an hour to clean it up--what a mess! After degreasing it, I used a wire brush attachment on my electric drill to grind off all of the paint (it's aluminum--so I won't have to worry about rust). Looks brand new now, doesn't it? Notice the new Kilby Enterprises manifolds now installed topside, which have standard ½-inch NPT threads.