another A/C issue

[Yarek]

I got the truck earlier this summer (2001, 2500, V10) and the A/C was intermittent, and to be honest, it would only blow cold for a few minutes and then quit completely.

I took it to a shop and they evacuated the system, put fresh refrigerant in and even checked to make sure there aren't any leaks. All checked out and the AC worked again! for not too long...

Took it on a little road trip and after a while the A/C would quit when I had to floor it on some uphills or under heavy acceleration. But it would come back on.

Recently it went back to square 1: it works for a bit and then quits forever.

Another issue I noticed is that the cruise control isn't very responsive in hilly terrain, meaning: it will let the truck slow down quite a bit on uphill runs, or let it roll quite a bit over the setpoint on descends. Which leads me to thinking that maybe there is a vacuum leak somewhere? I really don't know where to start the diagnosis.

Lastly: it is a 4 speed A/T and it sure feels like the truck doesn't like being in the 3rd gear. It skips quite quickly from 2nd to 4th and only in some situations it settles down on 3rd when I have to floor it on steep climbs. No rattle or anything, it just kinda skips through the 3rd relatively quickly, staying on 3rd for maybe 1-1.5 seconds. The transmission fluid seems relatively fresh. Still has some of the reddish color to it.

The truck doesn't make any weird noises. It has plenty of go, doing a great job pulling an RV trailer through the mountains last weekend. Not even sure these three issues are related, but they might be? The cruise control is a non-issue really; the 3rd gear thing: not too worried about it, either, but the AC not working reliably is an issue. Summers are hot here. And so are springs and falls ;-)

 

[RodeoRam]

On the A/C, when you say it quits completely, what do you mean? Does the fan stop blowing, or does it blow non-cooled air? If the fan stops, it could be the resistor block on your fan or the fan itself. If it is blowing warm air, it could be the blend door and/or actuator. I had to replace all of those on mine at one time or another.

Another A/C issue I had on my '01 was that with the A/C on, the output would switch from the dash vents to the defrost vents when I pressed the skinny pedal more. When I let off, the air would switch back to the dash vents. IIRC, that was a check valve in the vacuum system. I think it was near the top of the firewall. You could probably google it to find out.

Your uphill cruise issue could also be vacuum related, but then again, it might just be poor design/programming. Again, IIRC the 2nd gens had the vacuum line for the cruise running under the battery. Acid from the battery would eventually eat into the line causing a vacuum leak. I'm thinking that it's a physics or programming thing, though. When starting up a grade in overdrive with the cruise engaged, it is on the wrong side of the horsepower/torque curves, and the cruise/transmission take too long to react causing a big loss of speed. Try turning the O/D off before you start up the hill to see if it improves. On the downhill side, remember this is a 2nd gen before they incorporated downshifting and engine braking into the cruise control to keep the speed near the set point. As long as it was safe, I loved to see that MPG indicator peg on 99 as long as possible.

 

[Yarek]

On the A/C, when you say it quits completely, what do you mean? Does the fan stop blowing, or does it blow non-cooled air? If the fan stops, it could be the resistor block on your fan or the fan itself. If it is blowing warm air, it could be the blend door and/or actuator. I had to replace all of those on mine at one time or another.
Another A/C issue I had on my '01 was that with the A/C on, the output would switch from the dash vents to the defrost vents when I pressed the skinny pedal more. When I let off, the air would switch back to the dash vents. IIRC, that was a check valve in the vacuum system. I think it was near the top of the firewall. You could probably google it to find out.

Thanks for the reply. Yeah, the fan stays on, it just starts blowing a relatively warm air, possibly warmer than the outside air. It definitely does it when I floor it, and it just does it on its own after it's on for a while. Also: it keeps blowing the air through the dash vents, it just turns pretty warm quickly.

I read somewhere about the vacuum line under the battery. I'll look there first when I get a break.

 

[crash68]

You need to figure out if it's the AC system or a blend door(s) that causing the issue. I've read some year trucks had issues with the vacuum line going into the cab to HVAC controls cracking causing issues.
If you notice that AC blowing warm, check the larger of the two line going to the compressor if it's cold, if so your problem is probably with the blend doors.

 

[PaPitt]

iS YOURS A DIESEL OR GAS Truck .
I worked as a service advisor from 99 too 2007 i believe . I should remember your shifting issue .. But I'm going to say take it to a quality trans shop & I'M Going to saythey can fix that . I'm thinking it need a complete fluid & replace the filter with only a Chrysler filter .
If shop insist on using theirs of pdq parts. THEN Ask them if it doesn't fix it will the do it over & Use a CHRYSLER FILTER . yOU MAY have to take them the filter .
I over saw about 4 trans techs & they convinced me after about 2 year that the chrysler filter was better . . But a fluid change & replace the Transducer & Governor pressure Solenoid ..
.. Oh & the org pan gasket is a reusable gasket . If it has to be replaced it cost about $40.00. But it's good.

 

[PaPitt]

I might ask if your trans has an issue of up & down shifting at 42 MPH IN & OUT OF 3 & 4TH GEAR .
iF SO THERE is a battery cable on the passisde THAT has about 2 or 3 cables & they get corroded . We sometimes cut the plug joint out & SOLDIERED ALL the cables back together . & THEN RECOVERED with heat shrink tubing ..
I was the hero when I found that repair .