Join Date: Dec 2013
Location: Seattle WA
Vehicle: 2000 SLK 230 Sport
Other Toys: Yes (cars, bike)
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AC compressor replacement
I finally took my time to fix the AC in my 2000 SLK 230.
Since I’m in the Pacific Northwest, AC is not imperative in a convertible car. I postponed this job due my reticence to pay the stealership fee of $2500 or the $1400 asked by my trusted independent and went with my own scenario which I am more than glad to share.
First I checked the pressure, but since the AC did not engage (and it was like that for about two years), the reading was low. My next step was to feed 12V to the compressor, but that did not do anything. I next measured the port for a 12 V signal feeding the compressor and there was no power (due to the low pressure the shut off sensor for low did not close.
At this point I took my car to a neighborhood shop to have my system emptied and a leak test performed. Since those guys had the same modern AC machine as any upscaled facility, but their fee for this job being only $80 that is all I needed.
The result was an empty and leak free system.
Now my game plan comes into play.
I removed the compressor (if detailed steps are needed, please let me know) and I started diagnosing it. I found the coil on the clutch to be shorted. There was also a bad bearing.
I had to choose from replacing the clutch for about 130 bucks or add $100 and get a new DENSO compressor with clutch. I got the new compressor and I paid $237 with free shipping from “Parts Geek”.
What I need to point out is the fact that as soon as you place the item in your shopping cart a warranty warning pops up saying that in order to expect the manufacturer’s warranty you need to replace the condenser/drier and the expansion valve and show proof that the entire system had been flushed.
I ordered also the condenser/drier and the expansion valve including an O-ring set to assure a perfect seal.
While waiting for the parts I ordered the flushing tool sold by Amazon for $45 for PRIME members. I also purchased the flushing liquid (2 quarts), a suction compressor for $149 from HFT and a set of R134 Gages as well as one can died R134 and two cans of straight R134. I also got myself two tap can adapters.
The flushing is a real pain and after all parts are accessible the process took about 4 hours. The flushing itself does take a matter of minutes, but the drying process is the real pain. You need to have the entire system completely dry. I manufactured some clear silicon hoses and adapted fittings to match the joints of my air compressor and let it run at 25 PSI until dry. I had to do this process for the evaporator and for the condenser, since the lines dried very fast.
My next step was to put the compressor back in place and this is a very tricky step because while the front two screws are easy accessible, the one found at the rear is very difficult to put back. Also, if further details are needed as far as the exact tool and the process please ask. I replaced all O-rings and put in place the new condenser/drier and the new expansion valve and hooked up the lines. I vacuumed the system for 30 min even if it reached a reading of -30 after only less than a minute.
I left the car stay overnight and checked next morning on my vacuum to find that same reading I left the night before.
With all in place and good to go with the fill-up process, I took the car for a spin to have it heated up.
Now to the charging:
With the attached gages at both, high and low, (the high port NEEDS to be closed- ONLY fill up by the low port) I let the compressor run for a few minutes (again), than I attached the first can at the charging hose (yellow) and at running engine I emptied the first can completely. I used a scenario with two adapter taps at the end of the yellow hose to be able to continue the charging without venting the hose after each can.
At this point I had to figure out how much R134 the system will take.
The car needs 850 g and a can has 340 g. I used a scale to find out the weight of my first empty can and also the weight of the adapter tap. Doing so I was able to stop at a point at my third can and weight the remaining R134. I managed to get into my system exactly 850 g.
The compressor engaged extremely smooth at the half of my second can and this was a moment of joy.
I inserted a thermometer (job specific) in one of the vents in the car and after short time the temperature stabilized at 40 F which is what we want.
I hope someone will find this helpful and if any questions need to be answered I will be more than glad to answer them.
Here is a list of the job specific tools, the parts needed and the total cost:
Suction compressor: $149
E 12 socket (for the three screws which hold the compressor)
Angled ratchet wrench (imperative for the compressor screw at rear)
8 mm Allen socket for the lines on the compressor
17 mm wrench for the connections to the drier
10 mm socket for the nuts on the expansion valve and the mount of the condenser/drier
Electronic leak tester
Denso AC compressor: $237 (at parts Geek – shipped)
Expansion valve: $25 (at Parts Geek - shipped, but prices vary depending on manufacturer)
Condenser/drier: $29 at AutoZone (not available at other suppliers at the time of my job)
O-ring kit: $10 at parts Geek – shipped
Flushing liquid: 2 qtr. x $15 = $30
R134 standard: 2 x $15 = $30
R134 with dye: $20
Parts Total: $371
Total for this job specific tools:
Suction compressor: $149
Electronic leak tester: $65
Flushing kit: $45
Total for tools: $314
Total for tools and parts: $685
Doing so and spending about 10 hours on this job I saved between $800 and $1800 + bonding with my beloved toy which is priceless.