My 2003 CTD has started to exhibit a sympton I am trying to diagnose. About 2 seconds after start, I hear a pretty loud pressure release coming from under the hood. Sounds like either fuel pressure or turbo pressure. Close examination under the hood shows no obvious release of fuel. Is this normal? If not, any ideas? Thanks,

Mike

 

Do you have the Defrost or A/C on? It could be the compressor releasing pressure?

 

Yes. I had the A/C on when it did it. I thought the A/C was a closed system. Where does the A/C vent?