heyevan

At some point during the winter the A/C stopped working on my 2003 Expedition. When the fan is running in A/C mode, there is a periodic (10-15 seconds between) hissing sound that seems to come from under the passenger side dashboard. When the fan is switched to vent mode, the sound immediately stops. It doesn't produce any cold air.

Any ideas?

rpg393

Maybe TX Valve or thermostat. May need to see A/C shop. Hissing sounds like pressure leak from 'high' side to 'low' side.

Svein

I have the same problem on mine, any ideas where to start looking?

Bert

Look at the A/C clutch under the hood while it's on A/C. If the clutch is turning on and off at about that same rate, your freon is low.

Svein

Hi rtg143,

The cluch is turning on and off....
I put my car in the shop today for a "refill of freon" and I hope that's it.

jvb3190

I think I have a similar problem. When I turn the air on nothing comes out of the dash vents. The rear air seems to be blowing cold air fine. When I turn everything off there is a hissing noise from behind the selector switch, but otherwise no other noises. Also i can not get any air blowing through any of the vents; floor, defroster etc. The problem was also fairly immediate. The ac was working ffine the night before and the next morning not at all. Any help please?

Bert

That hissing sounds like a vacuum leak. Probably the control switch or the hose connection to it. It could also be another area. It stops with the engine off? Try to listen for the location to pinpoint the problem.