PeachParts Mercedes-Benz Forum - View Single Post

James L · #5 05-05-2010, 10:34 AM

Larry, my compressor clutch/pulley is making noise when on, the clutch/pulley is kind of wobbly when looking down like the bearing is going. Compression on the high side will not get over 150 psi (R12) even at full charge, can see freon moving thru sight glass.

There is a leak that I can not find; dye is in system but can not see any, also my sniffer does not detect any. I am assuming the leak is inside the R4 at the one of the clutch bearing/seals. When I remove the R4 I may take apart to see.

Seems like new R4s are harder to turn by hand, compressor works web site says have to use a spanner wrench, will not tun by hand. (good read);

STEP 2. SYSTEM FLUSH
It is CRITICAL that the system be flushed (cleaned) prior to installation of a new replacement compressor. The evaporator, refrigerant lines, and condenser (if applicable) must be flushed separately. Closed loop refrigerant flushing is highly recommended. Flushing with an approved flush agent is acceptable provided that the agent is used in the liquid state and the components are air dried using filtered/dried compressed shop air. Oil based flush is not recommended.
STEP 3. CONDENSER REPLACEMENT
Late model vehicles are being designed with compact, high performance parallel flow condensers which have very small
refrigerant passages. These small passages make it impossible for these condensers to be properly flushed. A good
example of this is the condenser on the 2002 – 2004 Honda C‐RV. The condenser should be inspected at the inlet port
(compressor discharge line) for signs of debris from a failed compressor. If any debris is present, it is highly
recommended that the condenser be changed.
STEP 4. ADDITION OF LUBRICANT
Replacement compressors are typically shipped dry (no oil). Use the type and
quantity of oil specified by the vehicle manufacturer or the CompressorWorks “AC
SYSTEMS TECHNICAL SPECIFICATION GUIDE”. PAG oils are used with R‐134a
refrigerant and mineral oil with R‐12 refrigerant. Add 2.0 – 3.0 ounces of the
specified oil to the compressor through the crankcase drain port or the suction port as noted by the ADD OIL decal. Rotate the compressor, using a spanner wrench or clutch hub turning tool, at least ten (10) revolutions to distribute oil. Note: Some compressors, for example GM H‐6 or Ford FS‐10, may not rotate by hand due to internal component preloading. For an orifice tube system, add the balance of the oil charge to the accumulator dehydrator (AD). For a TXV system, add 1.0 ounces to
the receiver dryer (RD) and the balance to the evaporator.
STEP 5. SYSTEM ASSEMBLY
Install the new replacement compressor, AD or RD, orifice tube or TXV, muffler or filter, and condenser (if required). Evacuate the system to at least 99.4 kPa (29.5 in‐Hg) of vacuum for forty‐five (45) minutes to ensure all moisture and residual flushing agents are boiled from the system. Observe the low pressure gauge for five (5) minutes to ensure the system holds vacuum. If vacuum is not held, leak test the system, repair leak point, and evacuate system again.
STEP 6. SYSTEM REFRIGERANT CHARGING
Recharge the system using the refrigerant type and quantity specified by the vehicle manufacturer or the CompressorWorks “AC SYSTEMS TECHNICAL SPECIFICATION GUIDE”. Use an accurate scale or metering device to ensure the proper refrigerant charge level. Crankcase Drain Port
Clutch Hub Turning Tool 350104 Rev. 4.09
Note: Improper refrigerant charge is a major cause of premature compressor failure and poor system performance.
Use a refrigerant leak detector to check the system for leaks. If a leak is found, remove refrigerant charge from the
system, repair leak point, evacuate, recharge, and leak test.
STEP 7. PERFORMANCE TEST & DIAGNOSTIC PROCEDURE
1. Start engine and allow it to reach NORMAL OPERATING TEMPERATURE. Set A/C system to MAX COOLING (RECIRC),HIGH BLOWER SPEED, all DOORS OPEN, and ENGINE SPEED @ 1500 RPM. Allow system to stabilize for 10 ‐ 12
minutes.
2. Visually check for loose mountings, rubber hoses or metal pipes that are contacting other vehicle parts. Theseconditions may produce a noise problem. Check all connections for possible leakage.
3. Monitor pressure gauges for proper operation. Excessive high pressure readings on high/low side pressure gages
may indicate one of the following problems:
a. Refrigerant overcharge.
b. Improper engine cooling system performance such as restricted radiator air flow, inoperable electric fans, and/or faulty fan clutch.
c. Blocked or restricted AC component (condenser, evaporator, orifice tube or thermal expansion valve (TXV))
passages resulting from debris caused by the previous compressor failure.
4. Monitor center dash vent temperatures for proper cooling. An average temperature difference between ambient
(86 °F / 30 °C outside temperature) and vent temperature of 20 ‐ 30 °F (11 ‐ 17 °C) is acceptable at about 1500
engine RPM but is dependent on ambient conditions. If poor performance is observed, please check the following:
a. Refrigerant undercharge. Can also be observed as frequent compressor cycling (on/off). b. Low / no power to compressor clutch. Can be observed as clutch slippage or non‐engagement.
c. Improper air source selection. Set A/C system to re‐circulating inside air (RECIRC).
5. Check entire system using an electronic leak detector. If dye has been added to the system, it is most important to check the system with an electronic leak detector. The indication of dye does not necessarily mean a leak is present (particularly at o‐ring joints and shaft seal locations). Always use a leak detector to verify leak indications by dye.
6. If excessive compressor noise is encountered, please check or verify the following:
a. Lubricant (oil) and refrigerant quantity. Noise may be due to an undercharged or overcharge of lubricant or refrigerant. Verify that the correct type and quantity of oil and refrigerant have been used.
b. Condenser restriction. Compressor noise may be caused by high discharge pressure created from a plugged
condenser.
c. Contaminated system. Debris from a previous compressor failure can destroy the bearings in the
replacement compressor resulting in excessive noise.
d. Improper flushing agent. Residual flush can cause severe compressor damage by a chemical reaction which
degrades lubricant performance.
7. Change A/C system settings to MAX COOLING (RECIRC), MEDIUM BLOWER SPEED (or LOW), DOORS CLOSED, and
ENGINE SPEED @ 1500 RPM to insure that the system controls allow proper cycling of the compressor by reduced
system performance demand. This does not apply to variable displacement compressors.

bio, not alot of room to take clutch off on car. There is also some special R4 service tools that may be needed. And it is not just the clutch but seals and bearings that go with the clutch when removed (may lose freon). Did the elec connection break? if not try some CRC electrical cleaner.