A/C cycling constantly ?
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Joined: Apr 2004
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A/C cycling constantly ?
I have a 2000 F350 psd. with aprox. 59000 miles. On a trip from So. Cal to Lake Havasu AZ and back, we had the A/C blowing all the way there and back. The Compressor kept on cycling then disngaging every 5 or 6 seconds. It would come on for 5 or 6 seconds then stay off for 5 or 6 seconds. It did this all the way there and back. The A/C is still blowing cold air. This just started, it has not always done this. It's very annoying when you are driving for 4 or 5 hours.
Thanks.
Jeff
Thanks.
Jeff
Tuned
Joined: Feb 2003
Posts: 495
Likes: 0
From: Cincinnati, Ohio
I wouldn't add freon without first putting gauges on the system so that you can check high and low side pressures. While cycling can be caused by low freon it can also be due to a bad low pressure switch, loose connection, failing compressor clutch,, etc., so it is better to know that you aren't possibly overcharging the system which can cause other serious problems like possibly damaging the compressor, along with poor AC cooling.
John
John
Tuned
Joined: Feb 2003
Posts: 495
Likes: 0
From: Cincinnati, Ohio
Jeff,
The spec for the cycle switch in the low side pressure circuit is closed at 35-45 psi and opens at around 22 psi. They should be able to put a set of manifold gauges on it to see if the switch is operating to spec and to see the pressures both low and high. The problem you are going to have is that FoMoCo doesn't use performance charts for adding freon in the case of R-134 like they used to with R-12. The procedure now is to evacuate, vacuum and then recharge the system by Freon weight using the capacity specified on the tag located on the radiator bulkhead or by the evaporator case.
John
The spec for the cycle switch in the low side pressure circuit is closed at 35-45 psi and opens at around 22 psi. They should be able to put a set of manifold gauges on it to see if the switch is operating to spec and to see the pressures both low and high. The problem you are going to have is that FoMoCo doesn't use performance charts for adding freon in the case of R-134 like they used to with R-12. The procedure now is to evacuate, vacuum and then recharge the system by Freon weight using the capacity specified on the tag located on the radiator bulkhead or by the evaporator case.
John
