a/c causing truck to stall

Check the fuse,s and relay,s

If they are good,check the coil.

now it cranks but wont start, has no spark, but does it set a trouble code? is your maintenance up to date? are there aftermarket parts on the tune up? or is it using delco? When you lose spark it shuts down the fuel. so you wont have that til you get spark. do you have one coil for 8 cylinders on that 2000 ? an ignition module can quit on you, then you would repair the distributor with new delco parts. If your system has other parts it may use a crank sensor. This is why codes need to be read next. for the best answers. They lead to tests that can help.

There is a diode in the compressor clutch wiring, when the clutch disengage there is a voltage spike, the diode prevents that from doing damage. I hope that wasn't what happened to you.

There is also a load placed on an engine when engaging the compressor. If the condition of the engine tune-up is lacking. Run-ability is poor? It does not take much more.

a diode can be checked for ability to pass current in both directions or shorted to pass current the wrong way. You could verify this by removing it from the harness and disabling the clutch during spark correction. reinstall if it passes tests and restore a/c operation...........But back to where you were in the prechecks...what is your parts group in use? for spark? What is the trouble code stored? Google the code for info about testing needs or report. A haynes manual from library or parts store can outline things to check in the engine controls, has photos, and gives checks and things to do.

the codes im getting are p0108 and p0161 for the o2 heater circuit and the map sensor. I just bought the truck a month ago so still learning it. 1999 chevy 1500 vortex v6... thought at first it was just flooded but the plugs were dry. I checked on google and dirty carb seemed to be the thing it talked bout most so im bought to go check that and I have a voltmeter and a vacuum pump so going to check map sensor while im there. didn't know that about the diode will have to look into that too.

Dirty carb? theres no carb !. There may be TBI. the haynes has a few things to take apart, check, reset, including idle air bypass. check fuel pressure, check fuel filter for plugged, clean throttle plate, verify injector fuel pattern view. what service manual are you using? sounds like you got some internet info smeared around. not pertaining to your year.

It's a vortec 4.3 with the Spider injectors. Lol. No carb there.

More like a squid than a spider, spiders have 8 legs LOL. But I was waiting for the asker to correct me...tell me what service manual he/she has, and see if they completed basic maintenance ever, and Identify their system and its prechecks...........all the more reason for engine with poor idle to crap out under load.

You can request manuals or read automotive database at the public library, get recalls and bulletins that pertain to your rig. Then, decide which source is understandable to you, since you just took delivery of this vehicle. If you dont have receipts or an inspection done, might as well get the news about it before you get your head in past your ears.

After your pinpoints for HEGO O2 and MAP, you would still need to google some info to lead you through familiarity and checks. it's been a couple days, so here's what I found to lead you.( google) 99 chev K1500 4.3L no spark, there is plenty of info to keep you straight, and some key security, as well as power distribution circuit info to keep you away from the diode if that info is actually incidental. Like if your a/c operation is a coincidence and you had a passlock code in addition to your driveability codes, your system has to be equipped, and you have to select that mode in the code reader. The rest of the list has all the basics. some say you pay attention to distributor position, mark it first if you disassemble where it tightens down.

throttle body I mean. which I did get cleaned. kind of hard doing any testing right with having to work and to top it off its suppost to be raining when I get off today. of course.. but good time to do alittle studing since it is a new vehicle to me. wanna still go in a make sure all fuses are right and working good and would like to test the relays. come on weekend.

After you google the no spark with your info about the rig you can start to see where the testing will lead. Inspecting things that enable spark first. The connectors, wires, power distribution, sensors etc for damage or anything to or from that is out of sorts.

is it normal for map sensor to read at about 4.88? seems to be holding..

You can read that reference voltage is supplied.... since you have no spark to run it. (V-ref is 5v) If you are at Bk wire with black lead and Lg with red lead on 12-14v scale...KOEO, read 4v, then start and warm engine, KOER same test points= 1.8v-2.1v. This wont help till you fix spark, right? That was some quickly found data for 4.3L v6 MAP testing, from "fix ya"

excuse me 0 to 14v scale, Bk means black wire pin to Map connector. and Lg means light green

KOEO key on, engine off...KOER key on, engine running, op temp. That is like applying normal manifold vacuum to the sensor vac hose port. You could bench test that with a hand pump.

Here is an easier one to see, read and understand... troubleshootmyvehicle.com/4.3L-5.0L-5.7L/how to test the map sensor

p0106, note, symptoms of map performance? engine dies as soon as it starts...........engine dies under load.... sounds kinda familiar...are you able to verify no spark still? You may want to arc a wire to a ground while cranking and leave out your spark tester. If your Map has enough to do with your symptom, it can cause it to crap out all by itself. ac may be just enough load added to do the symptom into it.

The verify spark test is what I am saying, like just position it to jump to a tool lying on the engine in view while cranking. if ya kno whut i mean

How-to-test-the-map-sensor, forgot the dashes between the words, sorry, sleep deprivation after the hitler youth meeting.....not

ok decided to start pulling the plugs and kind of check for spark as I go. when I got to the 4th plug it miraculously started firing and the truck turned over. its running rough. I think do to I broke a plug wire. and the heater water hose connecter broke so I cant let it run. tomorrow im going to get new plugs and wires get the hose connecter fixed and see where that takes me. im new to working on a chevy have had a jeep Cherokee the last 15 yrs so its a change.the spark pugs were a lot easier to get to on the inline 6 but kind of fun having something different to work on.

That is great, the spark wasn't fully lost, the shut off was caused by the load on the poorly running engine, that means you told enough to get good guesses. hahaha, I am glad to hear you made some leaps. try to get a metal hose mender if you can, brass is nice but any metal would do if they have the shape..... for plugs I can suggest extensions and a 5/8 with swivel. they help your back and keep your hands out of there. you can also use a reactionless if you need speed. that makes time. I like A/c delco for wires, plugs, cap, rotor the best. parts stores can get them in hours if you request and are keeping the rig.

Did the MAP troubleshoot help? the last time I pulled it up I was amazed. there is an absolute ton of great info there with that page and the other few pages about it. did your sensor respond to bench test? Our driveability guys would go up to a no start sometimes before the manager even exited the seat and yank the vac line and say, try it now! It would run bad but better than pushing !

Freaking fuel supply problem people DAYUM