I have a 2005 E-450 DIESEL RV with

 

I have a 2005 E-450 DIESEL RV with

 

I have a 2005 E-450 DIESEL RV with

 

Put down the smartphone and try on a PC

Sixto
93 E150 Chateau 5.8 191K miles

 

hahahaha, it just doesn't want to continue after ''with''

 

I have a 2005 E-450 DIESEL RV with

 

I have a 2005 E-450 DIESEL RV with 30k miles and very clean and original mechanicals.. almost looks new and no dry rot on rubber, hoses, etc.


While driving, the AC will alternate blowing hot and cold changing every few minutes sometimes and sometimes several seconds. As the AC goes from blowing cold to warm, there is a groan under the dash.


No problem I thought. Vacuum leak. I just need to located the vacuum leak. but there isn't one.


This E450 has a mechanical vacuum pump that is run off the serpentine belt with the AC, alternator, etc..


With a vacuum gauge I checked the pump while running and have perfect vacuum. Check that off the list.


Next I pulled the black vacuum line from the vacuum pump and plugged the same black line as it entered the interior of the van as it came through the fire wall and with a hand vacuum pump I checked the vacuum lines from the vacuum pump into the van to check the lines and the reservoir for leaks. Result was no leaks at all.. The lines and reservoir held vacuum no problem. Check that off of the list.


I pulled the panel off of the top of the dash and while driving and as the AC would change from blowing cold to warm I looked at the two actuators controlling air flow and neither of them change. Check that off of the list.


So I looked at the blend door which I think is what is opening and closing causing the air to blow from cold to warm. I haven't physically seen the door open or close while driving because I can't look under the dash on passenger side while driving.. but I think this is the problem..The door moves freely. With my vacuum pump I can open and close the door no problem with the actuator. It isn't stuck.


I used my vacuum pump to pull vacuum only to the dash controls by hooking the vacuum pump to the black line that goes up to the dash. With the dial control in the DEFROST position, I can pull vacuum on the pump no problem.


If I switch the dial control to any other position.... heat, AC, Vent..... I am unable to pull vacuum with my vacuum pump. Hmmmm. Is that normal??


One of the actuators on the dash has a blue hose to it and there is a "Tee" on the blue line so the blue line proceeds below the dash and I can't figure out where... Where might that go??


Any ideas??

 

I tackled the heater/AC on my E150 but I don't have a clue on this one. GREAT bit of troubleshooting, very thorough. The tee could be the connection for the defrost/floor setting where one of the actuators receives a partial vacuum so it only opens halfway to split the airflow to the vents. Doesn't have anything to do with the temp, though.
Good luck, I hate dashboard problems.
jim

 

Wow----raises almost more questions then it hoped to answer!

If I read correctly the direction of your air flow remains consistent with the Function Control electro-vacuum switch on the dash; A/C, Vent, Heat, Mix, etc etc---is that correct?

Does the air temperature change randomly or predictiably?

How do you know the blend door is moving freely?

(I'm subscribing to this thread so any replies will trigger a notification----hoping to help sort this out-----I think I know what's amiss.)

 

Moving the switch does move the vents from heat to defrost but doesn't always open the dash vents for AC. Defaults to defrost.

Not predictable.

After looking I don't think the blend door is the problem. It moves freely but I thought it kept opening to bring in outside air but stays closed as it is supposed to.

The servo below the panel on the top of the dash that opens the dash vents for AC moves freely and there is vacuum to the servo but it is weak vacuum. Not enough to open the servo by there is super vacuum on the black vacuum line below the dash. Hooking the black line directly to the servo actuaries the servo no problem so the servo is good.

Here is the strange thing that is somehow linked. I keep hearing a groan below the dash that corresponds with the AC going cold to warm then cold again. It is the same groan that you hear when you shut off the van. That groan is linked but can't figure out how.

Ideas??

 

Follow the vacuum lines from the upper dash servo, the one under the access panel next to the windshield.

That bundle terminates into a "block" which attaches to the back of the Function Control, an electro-vacuum switch that is labled A/C, Vent, Off, Heat, Mix etc etc. One of those lines is leaking or the connecting ports on the backside of the Function Control has issues.

The groan might be vacuum making noise as it escapes from somewhere along its path from the reservoir to the Function Control.

 

Thanks for idea. I did pull the radio out and reach up and pull and push and move them around and didn't see Ny of the actuators move. I pressure tested the lines and no leaks.

Could this be related to an AC compressor/AC valve problem which is causing the groan to come and go every 15 seconds? The groan doesn't seem to be comin from the compressor area but maybe it is the expansion valve leaking.