Hello, I was looking for some help here. I have a 1998 ranger with 2.3.
Several years ago the AC would toggle to defrost output when on MAX AC. No bid deal, just ran on on AC (not max). ~a year after this the same symptoms were observed on both max and normal AC. At this time I did notice when I was going ~40-50 and the ac output switched to the defrost when I let off of the gas the ac would return to normal vent output. Eventually the truck was hard to start, but once started and warmed up it ran fine.
I replaced the fuel filter, but no help. I found a big vac. leak in one of the small white vac. lines. I fixed this and the truck seemed to be ~80% better, but the ac still toggles from regular vent to defrost vent at certain speeds, but switches back to normal vent when I let off of the gas.
Check engine light has been on for ~1.5 yrs. I have not looked into this until now. I am due for inspection and thought I would just reset the check engine lite and be able to get my inspection to pass. Well they can tell if you re-set the computer. They were able to pull up the code P0171. I told them I had to clean the battery cable and that was why it was re-set. I was then told that I had to drive ~100 miles to get the computer to sense O2 and EVAP "not ready" Well I drove the miles and the check engine lite came back on. They told me I would have to get the issue fixed before the truck would pass inspection.
I have tried checking for vac. leaks by spraying throttle cleaner around the vac lines. Nothing found.
I'm looking for some suggestions on how to figure out where my vac. leak is.
I'm pretty sure it's a vac leak due to the fact that when I let off of the gas my AC output returns to normal from defrost output.
I'm currently looking for other obvious vac hose issues. Looking for PCV valve currently, but am not finding it. I think I may have found it, but not sure. I'm attaching a couple of pics that can show what I'm seeing.
I did find one possible missing vac. line. It looks like it comes from the bottom of where all the water lines combine. I'm not sure what this part is called or where the line goes to. I'm also attaching what I think is the PCV valve, but not sure??