A/C Help??????

[5810]

Hi, im having ac problems, the ac clutch for the compresor does not engage, i replaced the the whole compresor and still does not engage, and what does make the cluch engage, is it electronicly engaged, maybe there is a problem somewhere in the electronics, what should i check, can any one help me, Thank you

 

[5810]

can any one help me please,

 

[Bruce Rock]

Befor you replaced the compressor you should have checked to see if you had power to the clutch. Did you?

One interlock that prevents the clutch from engaging is the pressure switch on the accumulator. If the system pressure is low the switch will prevent the clutch from engaging.. I would check there if you don't have power to the clutch.

If the clutch wasn't working why did you replace the compressor?

 

[5810]

Thanks for the reply,i replaced the compresor because it was cheaper that just replacing the clutch(bought it on ebay,used ,good condition),and whats the normal pressure that the a/c system should be at.

 

[Bruce Rock]

Clutch Cycling Pressure Switch

The clutch cycling pressure switch is mounted on a Schrader valve-type fitting on the side of the suction accumulator/drier assembly in Aerostar vehicles, and on the top of the suction accumulator/drier assembly in Ranger and Explorer vehicles. A valve depressor, located inside the threaded end of the pressure switch, depresses the Schrader valve stem as the switch is mounted and allows the suction pressure inside the accumulator/drier housing to control switch operation. The electrical switch contacts are normally open when the suction pressure is at or below 169 kPa (24.5 psi); they will close when the suction pressure rises to approximately 300 kPa (43.5 psi) or above. Lower ambient temperatures (below 8°C or 46°F), during cold weather seasons, will also open the clutch cycling pressure switch contacts due to the pressure/temperature relationship of the refrigerant in the system. The electrical switch contacts control the electrical circuit to the compressor's magnetic clutch field coil when the function selector lever is set for air conditioner operation. When the switch contacts are closed, the clutch field coil is energized and the air conditioner clutch is engaged to drive the compressor. When the switch contacts are open, the compressor's magnetic clutch coil is de-energized, the air conditioner clutch is disengaged and the compressor does not operate. The clutch cycling pressure switch, when functioning properly, will control the evaporator core pressure at a point where the plate/fin surface temperature will be maintained slightly above freezing, which prevents evaporator icing and the blockage of airflow.

 

[V8BoatBuilder]

Who recharged the AC system after the compressor replaced? was it a shop, or did you do it?

Make sure the system was vacuumed first, the orifice tube replaced, and the system charged properly. You can verifiy charge with a gauge set.

Two simple tests to get you started:
1) take the clutch coil wire and put a multimeter to it. If everything is normal, when you select AC mode, you will get +12v. if you don't, then its an electrical problem.

2) Apply +12 to the clutch, only for a short bit. If it kicks over, then the clutch is fine. Use this opprotunity to check system pressure. R134 high side pressure should be 2.2 times ambient temp in deg F. Always charge by high side pressure readings.

 

[5810]

i mesured the voltage on the clutch coil wire and i only get like .1 to .5 volts , and you said it should be +12 volts.can this be caused by a bad fuse/relay,where should i look, and i replaced the compresor cause im short on money.thank you.

 

[Bruce Rock]

I get the impression you are over your head with this repair and don't know it. I am afraid I may be hurting you more than helping. You haven't answered V8BoatBuilders question about removing the air from the system and changing or at least checking the orfice tube. I question how you measured the voltage at the coil.