QuestionI have a 1996 Lincoln Town Car, 4.6L engine.
When I turn on the AC in any mode that uses the AC compressor, the clutch pulls in several times in succession for about 5 to 10 minutes. It pulls in harder than it should, I think. When it pulls in it makes a loud noise like a thud that rocks the car slightly, not the regular sound. Additionally, the lights (interior and exterior) dim almost to the point of complete extinction.
The system was serviced just prior to the problem's occurrance because the blend unit was found defective. So, the items that were replaced were: AC compressor, drier, orifice tube, blend door actuator, case w/door, and evaporator core, coolant temperature sensor, and thermostat. The system was evacuated and recharged. The problem persisted and another compressor was installed.
This work was done in September last year (2003). Of course, the problem does not occur when I take the car in for inspection, therefore, the problem is still present and gets worse such that I seldom use the AC system and now it is out of warranty.
Can you help with this problem?
AnswerPlease DEFINE your statement, being: the blend unit was found defective.
I need to know EXACTLY what you are referring to.
OK, You can have several possibilities:
1. The magnetic clutch that is attached to the fron of the A/C compressor requires a SPECIFIC spacing (AIR GAP) between the magnetic clutch and the compressor plate. If this AIR GAP is to WIDE you will hear a loud CLAP and or CLANK as if you dropped your empty beer can on the cement floor.
The AIR gap, Of which mostly everyone never checks when they install a new compressor should ALWAYS be checked and in your case the AIR GAP should be .020 to .030".
If it is any WIDER you will get the beer can sound.
Next possibility:
There is to MUCH refrigerant (FREON) oil in the system. This IS a very common mistake made when a compressor is installed.
As an example, let's say your entire A/C system has a maximum capacity of 7 ounces of refrigerant oil in it.
Most new compressors come with what is called a FULL CHARGE of refrigerant oil of which in your case would be 7 ounces.
When the OLD compressor was removed from the vehicle, The refrigerant oil should have been poured out into a measuring cup and in most cases is usually 2 or 3 ounces maximum.
The NEW compressors refrigerant oil should have been drained out of the NEW compressor and NEW refrigerant oil in the SAME EXACT amount plus 1 ounce should have been installed bac into the NEW compressor. Therefore, If you drained out 2 ounces from the OLD compressor, You would install 3 ounces in the NEW compressor AFTER draining out ALL of the NEW compressors FULL CHARGE of refrigerant oil.
IF this was NOT done you now most likely have 12 ounces of refrigerant oil in your 7 ounce MAXIMUM refrigerant oil A/C system.
Thus to MUCH refrigerant oil and this will cause excessive force in order to turn the internal workings of the compressor, Thus, Your dimming of the interior lights.
This is MORE likely to occur when the A/C has NOT been in operation for several hours as the oil during this non-use of the A/C compressor drains back into the compressor thus over loading the compressor with refrigerant oil, Thus your current problem.
Eventually your going to have one or more of the following problems occur:
1. Failure of the compressor.
2. A blown A/C hose.
3. Damage to other A/C components.
Please remember that this information that you are receiving is being given FREELY without ANY type of compensation due to many years of experience by a retired automotive diagnostic professional. If you have any other concerns on this problem, Contact me at:
meperganfortis@msn.com
As I may require pictures of your A/C system as this board does NOT allow pictures to be posted.
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