no air no heat
 

I have replaced the blower motor, resister and heat relay, briefly got the fan back on, but would not switch from vent to defrost, it did turn on and off. Now nothing. Also it blows out cold air when set to cold but only bows air as warm as the engine when on heat. Any suggestions? Need help!

Welcome
Can you provide year, model and engine size please.

I hope I am understanding you correctly, you are saying you had no fan action, replaced the motor, relay and resistor only to have fan action for a short while and it failed again?
Also you have little heat and the system is not switching from floor to panel to defrost?
Am I correct?

You are in the right place for great answers from good people; I will try to help until one more knowledgeable comes in but need the aforementioned information to look up any diagrams.

Are your fuses good?
Wire connections checked for good clean and solid contact?
Any vacuum leaks (hissing sounds)?
Any warning signs, what order did things go out (all at once?)
Feel confident your issue will be resolved soon.

Thank you!!
e350 7.3l diesel 1998
You are correct except the air is stuck on the upper vents (no floor, no defrost)

fuses look good, but i could be missing one. I have the front dash apart because i thought it may be the switch, looks fine, but again not sure. I don't hear any hissing noises and we've had the bus for 2 years and have never had the fan or heat up front. so i am not sure when/how it went

Again, thank you for your help

First things first. Let’s make sure we are on the same page. Do these look correct?

http://i1322.photobucket.com/albums/...73lfusebox.gif
http://i1322.photobucket.com/albums/...3lfusebox2.gif
http://i1322.photobucket.com/albums/...3lfusebox3.gif
http://i1322.photobucket.com/albums/...3lfusebox4.gif

If so check relay H and fuse #13 in both boxes.

I check H and 13 last night. Turns out the relay - - had blown again , hence it not working any more. Also 13 had a 60 amp in there, replaced it with a 50. So new fuse 50 amp at 13 and new relay at H. still nothing. I'm wondering if the switch, on the dash that changes from off to vent etc, could be stuck on off?