I have a 1996 F150 with a 302 (in case that makes a difference) that will only blow hot air, I cant get the heater door to stay closed to shut off the core this time of year, i ran the vacuum lines for the climate control and there didnt appear to be a leak anywhere. I also has no A/C if that helps as well. Just wondering if there is anything easy to do without re-running all the vacuum lines to replace them to see if that alleviates the issue

 

u could do what I do every summer I just pull off the coolent lines that run to the heater core just loop one of ur hoses to both water ports so no hot coolent goes to the heater core