I just got my 1990 F150 back from getting the fuel injectors cleaned up. I know my AC was working last week and now it just blows hot air. I don't hear the compressor cycling either. However, when I turn the AC to high, about every 30 seconds I hear a weird "swooooooooooosh" sound for about 30 second, then nothing. Sounds like it could be a vacuum leak somewhere. This is most likely the reason my idle is sporatic while the AC is switched on as well.

Would there be a reason to unhook something that runs the Air compressor while cleaning out the fuel injectors?

If so, where would I check inside the engine compartment? I bought one of those Chilton CD roms a while back, but it's pretty much useless when it comes to troubleshooting things.

Thanks
-Ed

 

Look on the passenger side engine compartment in the back for the aluminum tank. Thats your AC dryer, it has a switch screwed into it that might be unplugged.

 

I looked all over the place and didn't notice anything unplugged. I should also mention the other thing the mechanic did was add a new temperature sending unit (which I should have done myself!). Would replacing the temp unit have any effect on the A/C cooling operation?

Thanks
-Ed