Hi there

The most common problem on this unit is that the vacuum line for the a/c system gets cracks or holes in it right by the battery --- battery acid eats through the hose

remove the battery ,, and ware the l/r corner of the battery was ,,,there is a thin black vacuum hose that goes into the firewall ,,, use a flash light and take your time and look at this hose for cracks or holes..

give it a try and tell me what you find , we can go back and forth on this page

Chris

As far as that hose you found that goes to nothing ,,, start the truck up and see if there is vacuum on this line ,,,, if there is then cap it off and see if this effects your a/c ,,, if there is no vacuum to it ,,, then I would not worry about it ..

sometimes that black hose by the battery will have a bunch of small cracks in it ,, it will take a close look with a flash light to find it ,,,

if you recheck the black vacuum line at the battery and find nothing ,,, then at that point at the battery ,, you should be able to disconect the back hose ,,, start the truck up and make sure the hose has vacuum on it ... if it does and the line looks good ,, then we will have to remove the a/c controls and disconect the vacuum conector there and check the black line going to it to see if it has vacuum ..

the front cover just pulls off

then you can access the four bolts for the a/c controls

and then access the vacuum plug on the back to check the black line

Ok -- then you have to remove the auto a/c head ,, and on the back of it is a vacuum conector with about 5 vacuum lines in them , red, blue, yellow, white, and black ,, unplug the vacuum conector and with the truck running ,, is there vacuum on the back line ,,, this is the main source of vacuum for the system ..

tell me what you find

Chris

oK --- if YOU DID THIS WITH THE TRUCK RUNNIG,,, THEN YOU HAVE NARROWED YOUR PROBLEM DOWN TO ONE hose ,, that black vacuum hose ,,, now you know for sure that you have no vacuum to the a/c head on the black hose ,,, but I think you told me that you DO have vacuum at the battery at the black vacuum hose,, so your problem is inbetween these places on the black hose .. all the black hose behind the dash is not accessible unless you pull the dash ,, and this section does not see much action at all..

the only place on this black hose that sees high temp and weather and acid , etc ,, is in the engine compartment ,, so we are back to square one ... their must be a crack , leak or brake ,, in the black hose by the battery ,,,, follow that black hose as it comes out the firewall and goes by the battery and so on ,,, looking for cracks and such ..

you ca do an experiment and run a different vacuum source to the black vacuum hose as close to the fire wall as you can to see if this makes the system work,,,, if it does NOT ,,, then you know the leak is in the dash some ware in that black hose .... if it does repaire it ,, then the leak is in the engine compartment

OK --- now with the a/c system you have ,, the auto a/c system type,,, they a/c control heads are also known to go bad and cause this concern ,,, its more rare of a problem ,,, but it does happen ...

the best way to go any further with this is to use a vacuum pump to test the other vacuum lines for leaks ,,, but you probely do not have one of these ,,,, but there is a way we can do this ,,, what we have to do is get something that will fit into the vacuum conector you took off the back of the control head ,,, that vacuum conector that has about five hoses on it , red, blue , yellow , white , black ,,,, what we need is something we can use to jump the black hose over to the red hose ,,,so vacuum will get to the red hose,,, and then over to the blue hose ,and then to the yellow hose ,,, and then the white hose ,,, like a small straw off a can of WD40 or something like that you can find laying around ,,,and with the truck running ,,, use the straw on that conector on the black hose to send vacuum to each other line in the conector and see if you can see or hear a door open and close as you give it vacuum .. if all the lines check out ok ,,, and you can hear or see the vacuum motors working ,,, then I would have to say the a/c control head is bad .... and thats not good ,,,,, I think they are $450 ...

Chris