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Message: <blockquote data-quote="someotherguy" data-source="post: 20500" data-attributes="member: 6178">10-02-2024 Couple days ago the A/C is blowing HOT and I mean hot like the heater is on. As I started moving, it got cold again. Sit at a traffic light and it starts blowing hot.I asked over on PT dot net and got some unexpected answers - apparently more than a few people have had blend door problems with these trucks, and the need to reset the controls.  Someone else guessed the refrigerant charge was low.  A couple members wondered whether my engine cooling fans were working.  I wrote the fans off as it's been pretty warm out and the coolant temp seemed normal.  So I tried the blend door re-learn (turned the key on, set the panel to "auto", turned key off.  Pulled the 10A A/C fuse in the underhood fuse center, then re-installed it.  Started the truck, the temp on the panel defaulted to 74 as I expected, didn't touch the controls and let the engine run for 2 minutes.  Turned the key off for 15 seconds (at least 10, not more than 30, is what I read.)  Nope...Hooked up the gauges to see what was going on, and it became apparent pretty quick.  When the compressor kicked in, high side climbed steadily up to about 450psi before the high pressure switch cut it out.Wondering if I had a failed compressor and an orifice tube full of compressor guts, I pulled the orifice only to find a small amount of shrapnel, not the plugged disaster I expected:[ATTACH=full]1501[/ATTACH][ATTACH=full]1500[/ATTACH]Replaced it and vacuumed the system.  Waited for evening for it to cool off a little and started charging.  Coolant temp came up to 200F and stayed steady through the whole first 12oz can - but the fans never came on.  I pulled the scanner out to read the data stream to be sure the gauge wasn't lying to me.  It hovered right around 201-203F.  High side pressure seemed a bit much for just 12oz but it had reached the point to where the compressor was running steadily without cycling.  I put my shop fan in front of the grille and the high side dropped a lot.Pulled the cover off the aux panel where the fan relays and fuses live, fan #3 relay for the whole fan circuit is really hot.  It's got two burnt terminals and corresponding sockets.  Grabbed that relay from the other truck and the main fan came on.  I continued charging the system up with another 12oz and coolant temp stayed steady around 201F and main fan ran full time.  Second fan never came on.  Swapped the fan #1 and #2 relays, no difference other than the main fan shutting off with the relay out.  Checked the fuses with my meter, they're good.So far, it seems like the second fan has died, and put an extra load on the first fan and the system in general, which has melted the relay.During all this I've got 60F at the center vent with 24oz in the system, 201F coolant temp and only 1 fan blowing, just under 90F inside my garage, and the recirculate function not working.  Low side pressure seems a bit high around 55psi, high side 275psi.  This is about what it was doing before I noticed it blowing hot.  So, obviously I dug into the system when I didn't need to, based on a bad assumption, but that's OK.  I got to replace the orifice and re-visit the charge amount.  There's conflicting info out there on 24 vs. 26 oz.Ordered new fan assembly instead of just a new motor for the dead one, assuming the other one has been carrying the load for long enough it may be stressed/worn.Richard</blockquote>