When engine is started, A/C is on, and car is sitting still there is no cooling. The high pressure goes slowly to 450 psi and then the A/C compressor clutch is released. The high pressure slowly drops to about 340 psi at which time the clutch is re-energized and the pressure starts climbing to 450 psi and the cycle repeats. The low pressure varies from 70 psi to 110 psi during this cycle. As soon as I start driving the A/C starts working normally. What could be shutting off the freon flow?

 

????????????? Low side pressure is 30- 45 psi............ high side is about 200......... ??

 

Is the cooling fan working?

 

I've been wrong before, but it seems to me that there should normally be nothing in the loop that could impede the freon flow whether the cooling fan is running or not. When first started the engine and freon are all at ambient temperature and the fan isn't running. Is there possibly something in the loop controlled by the processor that can impede freon flow?

 

My apologies and thanks to m-chan68. I'm just an amateur on A/C systems and this is my first A/C unit with electric blowers. I didn't realize the high pressure could go so high if there was no cooling. The cooling fans weren't working and I found a burned contact in the fan connector that plugs onto the fan control module. The fans worked with 12VDC applied directly to the connector and the control module had 12 VDC on the output pin but the two wouldn't make contact when plugged together. Now do I have to buy a complete new fan assembly or can I get a replacement connector somewhere? Any help is appreciated.

 

The part number for a complete cooling fan and relay assembly from Ford is RF-259 if it is equipped with the 3.5L V6 engine. It wouldn't be the first cooling fan that has failed on one of these vehicles. I personally have replaced a few to correct engine overheat issues.

 

Does Ford sell a replacement/repair pigtailed connector? My fans are working super.