Ford Automobiles banner
1 - 7 of 7 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter · #1 ·
Hi I have a 2000 windstar V6. The A/C seems to continue to blow cold air after I shut it off. The indicator light goes out but the air stays cold, I have let it run for quite awhile expecting it to come to outside temp but it is enough I have had to inch the setting to heat on a couple of cooler nights. Is it possible that the compressor is not shutting down all the way and how would I check this.
 

·
Registered
Joined
·
543 Posts
Look at the compressor while an assistant turns on and off the A/C. See if the compressor continues to be engaged when the A/C is turned off. If the clutch is not disengaging then you may have a stuck relay. If the clutch/compressor is not continuing to be engaged then you may have frost or ice build-up on the evaporator core that is continuing to cool the air flow after you turn off the A/C. This may simply be due to humidity in the air that is getting frozen onto the evaporator core, or you could have an oriface that is not functioning properly, or the thermal switch in the evaporator core may be malfunctioning. Just a few thoughts based upon the inforemation given.
 

·
Registered
Joined
·
21 Posts
IF the clutch is turning when the AC is turned off, you may have a burned out relay. Check the continuity on the relay. To check this, pull the relay and check the resistence between the two large pins. If it shows infinite resistence (open circuit), the relay should be good (no way the compressor can be on if the relay is not closed). If the compressor is on, and the relay shows and open circuit, then it points to a mechanical problem with your AC clutch that's keeping it engaged without electricity running to the coil.

Tap on it a few times after turning the car off and see if that frees it up.
 

·
Registered
Joined
·
543 Posts
To add to Stein's post. The clutch coil is an electromagnet and when it is activated (switch on) it draws in the outer clutch into the clutch surface on the pulley. A spring inside the compressor provides for resistance and when the A/C is turned off, or otherwise cycled, the spring pushes the outer clutch surface away from the pulley, thus shutting down the compressor. It is rare, but this spring can break and not cause the clutches to disengage, and thus continuously run the A/C compressor. Added thoughts. As Stein suggests check the relay first, as this is the most common cause of the failure you describe.
 

·
Registered
Joined
·
4,352 Posts
Please explain, how one can look at a compressor and see if it is engaged or not.
 

·
Registered
Joined
·
543 Posts
If the outer clutch face (shoe) is drawn into the pully and turning, then the compressor is engaged, unless the compressor crankshaft is broken.
 

·
Registered
Joined
·
21 Posts
IF the outer face of the pully (also called the clutch) is spinning, then the clutch is engaged and the AC compressor is turning.

I should correct an error in my post. If the switches (low pressure and PCM Control) are sending a curing to the relay through the small pins, the relay will be turned on.

To test to see if PCM and low pressure switch are sending the correct messages to the relay: turn the car on, remove the clutch relay, and turn the ac on. The voltage between the two small pins where the relay is installed (not the pins on the relay you just removed) should be 12V. This means that the PCM has tried to engage your clutch and the low pressure switch senses a high enough pressure (above 25 to 28 psi) pressure to safely engage the compressor.

Turn the AC off and check voltage accross the two small pins where the relay plugs in. It should measure close to 0 volts because the PCM is telling the compressor to kick off ... thus terminating the power to the clutch coil by switching off the relay.

IF these two check out, it indicates the low pressuer switch, high pressure switch, and PCM are working as designed. If this does not check out. One of those three components is faulty.
 
1 - 7 of 7 Posts
Top