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Intermittent cooling

ErnieX on Tue May 05, 2009 4:26 PM User is offline

Year: 1996
Make: Ford
Model: Explorer
Engine Size: 6 Cyl
Refrigerant Type: r134A
Country of Origin: United States

My Explorer will cool just fine for awhile and then gradually loose the cool. I can turn it to vent for a little while and then back to A/C and it will work fine for awhile and then loose cooling again. When working it will run you out of the car with cold. I was told that it may be moisture in the system that is freezing at the orifice and blocking the flow and that I need to evac and recharge the system. Everything else in the system seems to be functioning properly, but I need continuous cold down here in FL. I do not see the accumulator or lines freezing up. Any thoughts?

Thanks in advance,

EE

mk378 on Tue May 05, 2009 4:38 PM User is offline

When it is not cooling, pull over and check if the compressor is still engaged. The plate on the front of the compressor pulley spins when it is engaged, and sits still (though the belt and pulley are still moving) when it is not.

If you find the compressor still engaged and you have a lot of ice on the lines, your pressure cycling switch may be stuck closed. This leads to the evaporator getting ice on the outside, which blocks the airflow through it.

ErnieX on Wed May 06, 2009 8:19 AM User is offline

Thanks mk378 for the quick reply. I'll check to see if the compressor is running when the cooling stops. I assume the switch you refer to is the low pressure switch located on the accumulator. However, there does not seem to be a reduction in air flow when the cooling stops, only a loss of cooling.

Thanks

EE

GM Tech on Wed May 06, 2009 8:52 AM User is offline

Also check for excessive compressor air gap between driver plate and pulley face. 0.020" is the norm- if excessive- the coil may not be able to pull the driver in on susccessive cycles after compressor is warm- then when coil cools somewhat, it pulls it in-- so again check for that when system is not cooling- front of compressor will not be turning- but may engage if you bump it with a hammer handle....be careful..

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

ErnieX on Wed May 06, 2009 5:13 PM User is offline

Well, GM tech, I think you nailed it. When the cooling stopped on thw way home, I stopped and checked the comp. It was not runnning. I flicked the front plate with my finger and it popped in and the comp started running. Measured the gap when I got home and it was approx. .050". I pulled the face plate and removed the spacer washer and reassembled and the gap is about right now. I'll verify it's working correctly tomorrow when I drive to work. Just wanted to post back and let you know what I found. I'll post back and let you know how it's working in case others have this problem.

Thanks again,

EE

GM Tech on Wed May 06, 2009 9:17 PM User is offline

I see about 5 or 6 a season- always high mileage, lots of cycles on compressors....Good to know you did not have to dig through a bunch of wiring schematics and tear up a bunch of your system to find it.....Thanks for the reply.

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

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