So, tinkering on my new to me 2004 F250 XLT CCSB yesterday, while checking some gauges on TorquePro I decided to activate the 4wd and was greeted by my A/C switching to defrost. I had already done a little reading and knew that indicated a vacuum leak to the auto hubs. Feeling around I could tell the right vacuum line was intact but deteriorated so I was pretty confident it was an easy fix.
This morning I picked up some replacement vacuum line (actually 3/16 fuel line) and crawled under the truck. Right side line pretty much came apart in my hand. Got the old stuff out and decided to see if the hub holds vacuum. Connected my mighty vac, gave it a couple pumps to about 7-8 in HG and let it sit. Decided to replace the left side line at this time. When I was done removing the old line and getting the new one on the left I checked the pump, still holding vacuum. Finished off the right side connections and checked the left hub. It also held vacuum for about 10 minutes so I finished off the left connections.
Thinking I had this whipped I started the truck, turned the A/C on and then activated the 4wd. Immediately the A/C switched to defrost. I checked all of the vacuum line connectors, everything seems like solid rubber. I suspected that maybe one of the hard lines might be cracked but decided before chasing that I decided to check the vacuum coming off the PVH.
I connected my pump/gauge where the line from the PVH makes the first connection rather than try to get the dual connector off the solenoid. Once everything was connected I hit the 4wd switch and again the A/C switched to defrost. Since everything but the PVH was eliminated for this test I have to believe the solenoid itself is bad. That or the hard line between the solenoid and first connection now that I think about it.
What are y'all's thoughts, am I on the right track?
This morning I picked up some replacement vacuum line (actually 3/16 fuel line) and crawled under the truck. Right side line pretty much came apart in my hand. Got the old stuff out and decided to see if the hub holds vacuum. Connected my mighty vac, gave it a couple pumps to about 7-8 in HG and let it sit. Decided to replace the left side line at this time. When I was done removing the old line and getting the new one on the left I checked the pump, still holding vacuum. Finished off the right side connections and checked the left hub. It also held vacuum for about 10 minutes so I finished off the left connections.
Thinking I had this whipped I started the truck, turned the A/C on and then activated the 4wd. Immediately the A/C switched to defrost. I checked all of the vacuum line connectors, everything seems like solid rubber. I suspected that maybe one of the hard lines might be cracked but decided before chasing that I decided to check the vacuum coming off the PVH.
I connected my pump/gauge where the line from the PVH makes the first connection rather than try to get the dual connector off the solenoid. Once everything was connected I hit the 4wd switch and again the A/C switched to defrost. Since everything but the PVH was eliminated for this test I have to believe the solenoid itself is bad. That or the hard line between the solenoid and first connection now that I think about it.
What are y'all's thoughts, am I on the right track?