Had a friend do a pressure test on my rad he pumped it up to 15 psi which held for a min then dropped to aprrox 13psi. Is that normal or should there be concern. We did the test due to using a very small amount of coolant periodically. We did not find any obvious leaks only trouble I am currently having is the heat/ac only blows out of the defroster which happened after I changed the thermostat due to a leak around the housing.

 

You have a vacuum leak in the vacuum vent control circuits.
Check the white vacuum line on top of the heater box under the hood.

 

^^^^ That white vacuum line does not control the blend door, it controls the fresh air door.
You do have either a vac leak or a faulty control ****. The vac lines you need to look for hook in on the bottom of the heater box IIRC.

If it dropped to 13psi in a min or less, and then continued to drop, yes you have a problem. If it dropped to 13psi in 4-5 min, no thats w/in normal specs still. Might have a small leak, but good luck finding it as it wont be leaking hardly any coolant.

 

What does the blend door have to do with it?
When that white vacuum line breaks you loose all vacuum to the vent system and the all the vacuum motors fall back to the no vacuum position and that makes the air only come out the defroster vents.



/

 

That white line only runs that one door. Your defrost door is run by the red line. And it looks like its a black like that actually supplies main vacuum from the engine bay. If the white line was broken and you would only have the vent problem on max AC. Not with both heat and AC.

 

What you are missing is the white line brakes a lot and when it does none of the vacuum motors work and they all return to their rest position. If you look at the diagram above you will see that with no vacuum on any of the motors the air is sent to the defroster vents. It has nothing to do with if you are on heat or A/C. That is just the Ford designed it for safety reasons. If you would read the other threads that had this same problem you will read that 95% of the time the white hose caused this same problem.
The rest of the time it was no vacuum to the system.

 

Take a close look at that diagram. if the HVAC **** is switched on to anything other than max AC , there is no vacuum going through that white line. It is removed from the vacuum circuit, and is just an empty line, unless you have the control set to max ac. I dont care what other people may have thought their problem was, if your diagram is accurate, that little white line is not what is causing this guys problem.

 

I do not take it he is wanting heat right now so I think he is talking about MAX A/C.
The odds are that he is not using Normal A/C, I do not think many do.
You are right as to what you are saying but you have to read between the lines on most of these post.

 

I dont try to assume anything when diagnosing a problem, every time I do i end up being wrong. I will give an educated reply based on facts given. If I am given bad info, its not my fault. People need to be specific when asking about a problem, its the only way to get a good answer online.

So I wonder what ever happened to the original poster?

 

I was out of town away from computer access for awhile. I appreciate all the responses. I do however have an update and no clue... I was driving the truck this morning and now and not knowing why the heater/ac is all blowing correctly to where I select it. So would us pressure testing the rad have fixed this problem some how?

 

No it would not.

 

Thats what I figured so Im am a loss...