New Compressor

[mekelly]

Had the A/C compressor clutch fail on my 1994 Expedition about 2 months ago. The compressor was also slowing leaking refrigerant from the main body seal. Cool weather in Atlanta so no problems. Got the shorter drive belt, disconnected the compressor switch (on the compressor) and bypassed the compressor.

Now that's the weathers turning, I figured I solve the problem. I didn't take detailed pictures and descriptions but the job is very easy. This write-up assumes you have a basic knowledge of auto repair, auto A/C systems and manifold gauges. If not (especially the A/C part), think twice about proceeding. A/C work can be very dangerous given the nature of refrigerant (think frozen eyeballs), exploding refrigerant containers, high pressures, etc. You MUST know how to use a manifold gauge set.

Here's what I did:

Bought the following from RockAuto:

- New 4Seasons FS10 Compressor
- New 4Seasons Accumulator
- New Fixed Orifice Tube
Purchased as a package, was about $150 with discount.

Bought the following from Autozone:

- Vacuum Pump (full price refunded when returned)
- Orifice Tube tool (full price refunded when returned)
- 8oz. Pag 46 oil ($9)
I already had a set of new A/C O-Rings for the Explorer. If you don't, you'd need to purchase them. They're about $10 or so for a full set.

Performed the following mechanical work:

PREP WORK -

- Removed air intake tube
- Removed fan, fan clutch, radiator shroud (to facilitate belt swapping)
- Removed air box (to better access orifice tube location)
- Connected vacuum pump and vacuumed system for 5 minutes
- Stand the new compressor on it's clutch (front end down) for several minutes to ensure the clutch seal is lubricated and doesn't leak later.

REPAIR -

- Disconnected liquid line at fitting and removed old orifice tube (location is below the airbox)
- Oiled new orifice tube o-rings and inserted in liquid line, reconnected fitting
- Removed bolt holding A/C hoses to back of compressor using a 10mm socket
- Removed 4 bolts holding compressor to engine using 10mm socket
- Removed compressor
- Installed spacers that came with compressor and bolted new compressor to engine, torqued to 20 ft. lbs.
- Smeared a little Pag oil on the o-rings when the A/C lines connect and bolted A/C lines to back of compressor, torqued to 16 ft. lbs.
- Rotated the compressor shaft (not just the pulley!) ten revolutions to ensure the compressor didn't hydro lock when started.
- Reconnected compressor switch

Note - my compressor came with 3oz. of oil installed and there was a still a vacuum when I removed the shipping seal so I didn't worry about draining and refilling it.

- Disconnected electrical connection to low pressure switch on accumulator
- Unscrewed low pressure switch on accumulator using an open ended wrench
- Removed Accumulator (need quick release tool for one of the connections and wrench for the other. Also need to loosen screw on bracket holding the accumulator on the bottom.
- Poured in 4oz. of Pag 46 oil and 1/4oz. of dye into new accumulator.

Note: My Explorer takes 7oz of Pag oil and 24oz. of R-134a refrigerant per the sticker on the evaporator covering. My orifice tube was super clean. No clogging, no brown/black oil, nothing. Looked brand new. If yours shows signs of metallic debris, brown/black oil, etc., you need to flush your system. As mine was clean and I was replacing both the accumulator and the compressor, I elected to not flush the system and added back a full 7oz. of oil.
You may also have to replace your condenser if it's clogged, all dinged up, leaking, internally contaminated with debris, etc. There may have been a trace of oil left in the condenser and/or evaporator but I deemed it too small to compensate for. Too much oil is bad, too little oil is worse. I also have a small digital scale that I used to measure how much oil I poured in to ensure it was extremely accurate.

- Replaced o-ring on low pressure switch fitting on accumulator and smeared Pag oil on it.
- Screwed on low pressure switch
- Replaced accumulator o-rings and smeared Pag oil on them
- Installed new accumulator (snap quick connect together and tighten nut on fitting).
- Tightened bracket that holds accumulator
- Reconnected low pressure switch electrical connector
- Immediately vacuumed system down for 10 minutes to remove air.
- Closed manifold gauge valves, shutoff vacuum pump for 10 minutes to see if it held vacuum. It did (if not, you need to find the leak before filling).
- Resumed vacuuming system down for an hour.
- Did another 10 minute leak test before installing refrigerant (it passed!)
- Refilled with 24oz. of R-134a using the small digital scale (don't forget to purge air out of the manifold lines after connecting the refrigerant). Put in 3/4 of a can or so and then started the engine. Double checked hi/low pressures against a temperature chart to ensure they were as spec'd.

Note: I did have to jumper the compressor two times to get it to begin sucking in new refrigerant after I'd put a can in. Only do this for several seconds at a time as you don't want to run the compressor without enough refrigerant carrying oil to lubricate the compressor.

- Check vent temps using a vent thermometer and was getting about 40 degrees on a 74 degree day. Not bad!

 

[Number4]

Nice details. Had to use my AC this week, felt like it was in the 70's if it wasn't.

 

[mekelly]

Thanks. Yea, I thought I'd have more time but even with outside temps in the low 70's, the car sits in the sun and get's hot!

 

[trashtruck]

great write up even though I'm a much bigger fan of roll the windows down and drive faster.

 

[Jason94sport]

My orifice tube was super clean. No clogging, no brown/black oil, nothing.

Luck you. I had black death twice!
My AC is on anytime I drive.
I know you didn't but I'd add to flush out the condenser & the lines.

 

[mekelly]

I got lucky that the clutch failed before the compressor suffered any kind of catastrophic failure.

I agree with you that the vast majority of the time, the system should be flushed. The fact that the orifice tube was spotless, led me to not flush it this time.

 

[larrydd999]

Good write-up! Did just about the same thing as you a few months ago, also changed the filter/drier and the evaporator. Filter/drier because the system had been open and the evaporator because it broke when attempting to disconnect one of the fittings. Also flushed the system, again because it had been open for quite some time (A/C n/f when I purchased the vehicle 4+ years earlier). It's not a big deal to do, especially with the R134a systems.

 

[OneofMany]

Well done. Let me point out that drawing a vacuum longer is better. 30 mins minimum is standard procedure. 4 hours is recommended. It doesn't hurt to leave it drawing a vacuum overnight. To know if you are loosing vacuum while pumping use this formula:
Atmospheric pressure at sea level (psi) - Atmospheric pressure at your location (psi) + Rated vacuum pump efficiency = actual efficiency
The point of the exercise is to surpass the boiling point of water by reducing the pressure and thereby being able to remove it. Ambient temperature has an effect of course. Doing this on a warm day helps and or running the engine a while to raise the temp of components helps also. You should be able to get close to the actual efficiency of the pump. Monitor the vacuum as the pump is working and observe a continued falling of the reading as moisture is boiled away. Once having reached close to the actual efficiency or it stops falling, shut the valve to the vacuum pump on and observe the gauges for a change. A quick raise indicates continued presence of moisture or a large leak, a continued rise over time indicates a leak. Observe the holding of vacuum for 30 mins or so. Measure how much pag oil was removed from the system while drawing a vacuum and inject the proper amount back into the system with your refrigerant. Nothing is ever 100% sealed.
As mekelly did, the receiver/drier/accumulator should always be installed last when opening a system. Running the compressor while filling the system with refrigerant should not be required, but aides in fully emptying the can as pressure rises in the system. You can charge/fill the system on the high pressure side only with the compressor off, but should be avoided... just be patient. You can help speed the transfer of refrigerant from the container to the system by holding it in your hand to raise the temperature of the refrigerant. The container will get cold as it empties, shake it while holding it and you will feel the cold liquid refrigerant contacting the container wall. Once you do not anymore, the can is empty of liquid refrigerant.

 

[mekelly]

OneofMany, spot on!