I have noticed a hissing sound that comes from behind my A/C control pantel inside the truck. Is this normal? If not, what causes this noise. It's been there since I bought the truck a year and a half ago. Also, in case you haven't picked up on it, im not a mechanic nor am I mechanically inclined since I live in an apartment and only have a small rachet set for a tool collection, but Im having a hell of a time trying to change my spark splugs. I just can't get reach them. Im needing to replace them and I just cant get to them, especially the ones that would be on the passenger side of the engine block. There is too much stuff that I know nothing about that is in the way. Any secrets??

 

Sounds like a vacum hose leak. The vacum lines that close the various doors for the heating & cooling system are connected to this control unit. One may have come loose or broken. What year is your truck? If there is room you could just reach up under there & check for a loose hose. Does your heating & cooling system work ok?

 

I have a 94 F150. The A/C is working great (nice and cold) but if I keep the control on Max A/C I notice that when I accelerate, the air stops blowing from the vents until I let up off the accelerator. So I just keep it on Normal A/C and it works fine. Heating works great all around. Should I be worried about this????

 

I bet you do have a vacum leak. When you accelerate vacum normally decreases but in this case with a leak there is not enough vacum for your system to work properly. I have a 92 ext cab F150, 302 and do not experience the problems you have. Look under the dash for a broken or pulled off vacum line. Your gas mileage and idle control should be effected by this vacum loss.

 

Another thing to remember about the A/C is that when you floor it, the A/C compressor is shut off until you let up on the gas. This gives the engine a little more 'passing power' that is otherwise used by the compressor. But, considering the hissing sound, try to track down a vacuum leak.

As for the spark plugs, you might want to go get a decent set of extensions and a spark plug socket, maybe even a universal joint. If you want relatively cheap: Sears Craftsman 3/8" extension set (3 pieces)=~$20, spark plug socket ~$5, 3/8" universal=~$8. The plugs are a PITA to get out, but there's really no secret to it; just trial & error!

Good luck-
Chuck