I have the AC re-charged, so they tested the lines. When I left there I could have made ice with that air. I hadn't used it again until we left on a 4 day trip and needed it. Came on cool not cold and went warm.. On our way back, running the highway now, we really needed it and tried again just get get hot air..

I checked fuse 27 and good! I check the clutch and it's working as it should. In my yard, just sitting there I can again make ice.. Arg... Read something about a blower door that stick and air does pass as it should? Please, where is this? Is this the next item to be checked?

 

There is another thread that is having fits with this . Yes there is you tube videos about foam sticking between blower doors . But yours works at idle . Those doors are driven by 12vdc not vacuum .
One thing to check is clutch spacing on compressor see you tube . Another is intermittent clutch relay in fuse box ,drivers fender . That was my problem . Your charge could be off and freezing up at speed . . You need to see if your clutch is dropping out at speed or needs shimmed or reduced . There is a feeler guage check for spacing ..
The pcm recieves the pressure switch inputs and the manual or auto ac controls . The pcm then starts and stops clutch relay by controlling ground. . Try running rpms up to 2500 and watch clutch .

 

I just had basically the same issue. Was coldest at idle. Found out it was a clogged evaporator. Replaced it and the orifice tube and it's cold again. You will need a set of gauges to verify but watch the gauges and the low and high side should be steady. If there's a blockage when the compressor kicks on the high side will climb and the low side will fall and the compressor will kick off to protect itself. But if your compressor is kicking on and off as it should this isn't your problem. If it's staying on like it should then you could have a weak compressor. Good luck.

 

I did go for the blend door and though that was working, it's not the issue. That was a project! It stayed cold for several minutes as I tested in the yard and drove around, but did eventually warm and go hot. I missed checking the clutch once it went hot.. dam. I will today.

The relay seems to be an easy swap out, so that's next (along with checking the clutch at heat). I'll also swing by a friends house and check high/low side for pressure changes.

The blend door made sense to me for the cold at start, then going warm/hot with time. I was dis-appointed that wasn't it after all.

 

Have you checked the air gap on the a/c compressor clutch? Pretty easy to check and from my recent research, this can cause intermittent a/c. Should be around .023" plus or minus .010". I'll be checking mine tonight on my truck. Just need a feeler gauge or you could probably get a ballpark measurement with a spark plug gap gauge.

 

My buddy put his gauges on and Static was off per ambient temperature. Sounding weird going on. Started up the truck and AC and pressure was high and a some was bled off. Pressure then looked good as the compressor ran a couple cycles and things looked good... then the compressor stopped cycling and pressure rose. Didn't catch at what psi that happened..

When the compressor runs, great cold air! Really don't know at what psi the pressure switch is supposed to kick on and shut down the compressor. I have a feeling the pressure switch may be activating early. I have the gauges now and once I know can re-run the test and watch for this.

Clutch relay was running very hot and didn't like that, so I did replace it.

I will check the clutch gap, yet hard to think that over 16yrs it would lose space and not wobble or something.. At this point I will check any suggestion off the list.

I'm looking at age and a possible clog (as suggested earlier). Auto Zone sells a AC flush. You know of it or something better?

 

well you have 2 pressure switches I think, 1st one for sure that is supposed to cut off the compressor if the pressure goes below about 20psi.
I think it also has a high pressure limit that cuts the compressor off if the pressure goes too high on the high side.
The gap happens probably due to wear over the years and is plenty possible. You are right if the bearings are worn there could be wobble, but the gap can open up and allow the clutch to slip or not engage at all if the gap is too wide.

 

I did find both! One is a bit trickier to spot. Looking for that high number for tomorrow I test again and look for it. To replace one means the system gets drained (I believe). So it only makes sense to replace both and flush. Now to understand which connections to pull and what seals to buy..
Gap I will gauge tomorrow as well.

 

I wouldn't replace the sensors unless they test out to be bad. I think they have check valves under them like a shraeder valve so they can be removed without losing freon, but not sure. I know on other vehicles I've had this is true.
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I believe you correct and plan a flush and replacement, which does means replacing some seals to do so. Main reason I'm looking for those high end numbers to help decide..

Test out to be bad? If they turn on/off within parameters.. is that not the test? Please... How to test others wise?