My 1979 f 250's heater a/c will work for awhile and then the fan just turns off intermittently. I replaced the switch and I am still having this problem. Should I just go ahead and replace the Blower motor or could it be something else? Thanks in advance for any input.

 

Did you have any luck with it?

 

Catfisher,I have the same problem with my 73 F-350.I replaced the blower motor and had all other parts checked out with no help.When I use the heater or the AC the fan will run for a few minutes and then quit for awhile and then come back on.Then after it is left on the fuse would blow so I put a fused breaker in but it still does the same thing only now I don;t have to change the fuse out when I need to defrost as that is all it is good for anymore.I have searched these forums and found no answer to this problem.I do not have this problem in my 71 or the 72.Good luck and let us know if you find out what is going on.
"bowties in the rearview mirror"

 

Hmmm.... I had the same problem with my 77 f150. I have the dash off of my 79 now and it seems that just wiggling the heater/ac control panel will make it turn off and on. I'll let you know if I find any kind of explanation as to what is going on. Thanks for letting me know that I'm not alone!