Hi ,, new here,, I have a 97 fr150 i bought new and have 232600 miles on it.

A month ago the a/c went from working fine to everytime that i have the air coming out of the vent and press the throttle hard the air shifts to the defrost until i let off the throttle.. any help would be great,,, thanks

 

SEARCH keywords "+defrost +vacuum"

 

exactly what mine did. check your vacuum lines

 

Thanks for the info. I just did what you said and i have the original manual. This was no help as the manual has only maintenance stuff and no troubleshooting... thanks for the reply

 

Alex... what lines did you find leaking... I was thinking about a leak but had no idea where to start looking.. thanks

 

it was between the battery and the firewall

 

Thanks for your help. I will look at the hoses that are behind the battery.... to the firewall