Ok I wasted the better part of a Saturday trying to be proactive and do some maintenance on my heating and air system. My complaint is with heater on high with thermostat all the way to the right and vent selection on dash only so to get maximum heat at your face. The amount of air coming out want even make your hair blow. blower itself is for sure on high I can hear it. If you change the setting to max a/c and turn the thermostat all the way to the cold side you get alot of air flow. I took the blower out and could see alot of dirt embedded in the a/c coil. I went to the trouble of actually taking out the entire coil (not a fun job) and cleaned the coil very throughly,reassembled and not a bit of change in the amount of air flow I got. What am I overlooking? Also took the inside cover off of the heater core just to inspect and it seemed to be pretty clean. Also I did a search to try and figure this out and learned alot on this system. Is it normal to have the compressor cut on and off all the time no matter what setting the system is set on? Thought I might have the air gap problem I read about and was going to try taking out the shims at the clutch but never got that far. At this point I just want the air to blow out the vent with some force I will deal with the a/c not working right when it gets hot again. I did read about a plastic bag that could possibly get sucked up in the system and cause a blockage but don't really see how this is possible could some one elaborate on this situation?

 

sounds like your damper door may not be opening or stuck - I'm not that good on the auto air but can u see the damper move when going from heat to cool in there ? Could possibly be stuck in a default normally closed position also, but somebody that knows more than me will be along shortly.

 

I think I am about to figure it out.

 

well I figured it out. I found out that the way this air box is designed it makes the air flow go threw the a/c coil for cold air and when hot air is needed it has to go threw the a/c coil and then the heater core coil as well. The air flow just will never be the same on heat as it is on just a/c. The only other alternative is to replace the blower motor with a new or stronger one to get more powerful air flow(wonder if there is such a thing). I guess I did help things out some by cleaning the a/c coils but as for the rest of the system all is in correct working order. I have worked on other older Ford trucks and there air box was not designed like this. I think ford did a bad job on this design. If the blend door worked in such a fashion as to only go threw one or the other coils when either cold or hot air was needed it would perform a lot better IMO. At least I can say I thoroughly understand the system now and might be able to help out others with there problems in the future. Guess that makes me the guru now! I am planning installing the heater hose cut off mod in the future with the ranger valve and I know exactly how to do it now and what it is going to do for my summer time a/c needs. I wondered why ford didn't put one in. I know why now but can still see some benefit from doing the mod to keep hot water out from under the dash circulating thru the heater core inches away from the a/c coil trying to cool things down,kind of working against itself there. Anyway enough ranting . Hope this might help someone else in the future.

 

I'm not an auto technician nor have I ever used heat in my truck but I am a residential and commercial hvac technician. If you turn your home's a/c on cool and then heat you'll notice a difference in air flow. The blower speed is much lower during heating. This is to pick up the heat without cooling it off. If too slow on cooling mode the coil can freeze so the fan speed is on high or med-high versus low or med-low on heat.

I'm just wondering aloud if an auto a/c tech can confirm that this is how blower motors on vehicles works as well. The principle of all refrigeration is the same but again, I know not how it's wired or set up in auto.

 

I think they route air this way to utilize a.c. for condensation on windows.

 

Yes, it goes through the a/c to remove moisture from the air so the windows don't fog up. My 2000 excursion isn't blowing as hard out the defrost either. The air isn't getting very hot either. The engine temp seems fine (needle almost halfway up gauge). Was thinking maybe blend doors aren't working correctly? This is the 1st Ford I've ever owned so I'm not at all familiar how their system works. Could there be valves in the heater hoses that aren't opening all the way, or controls for those valves not working?

 

your excursion should be equipped with a vacuum controlled valve to cut off the flow of water. could be that it is not operating properly or your heater core is stoped up. That would be the first thing I would check.

 

Ok I am wanting to get to the bottom of this. I brought home a company work truck this weekend.(2005 f-350 6.0) If appears to have the same heating and air system on it. The air flow it is producing is quite a bit more than I am getting in my 2002 f-350 model. Why? Don't want to start a poll or anything but just curious who is happy with the amount of air flow they are getting out the vents,defrost,and floor. Anything that can be done to increase air flow? I am going to change out the blowers between the two trucks just to satisfy my curiosity.

 

FYI....on my '00 SD, there is a slightly less amount of air flow from the dash vent when in heat vs a/c. The only way I could tell real good was to attach a string to the vent and compare how it floated in each position. I have no idea why the difference but my system works fine.

Max a/c should not change the blower speed...all it should do is close the air system off from outside air. (That keeps out that stinky smell from those diesels...oh, wait...lol) It does increase the sound of the blower because of this but not the speed.

Hmmmm....swapping parts on the company truck....don't get them confused...lol

 

Thanks, I'll check the vacuum valve on the heater hoses