Vinscully50

So after years of fighting with it, I finally got my cooling fan running normally (turns out it was bad wiring under the dash). My AC has been fully flushed and recharged. However, when my car is cold and I turn my AC on it wants to bog and stall when it's at a stop and it feels sluggish when driving. That is until the car is warmed up. After it's warmed up it runs fine.

In the last couple of years my car has had similar stalling issues. I replaced the IAC Valve, the Coolant Temp Sensor and the TPS. I also have replaced every vacuum line. I went and checked TPS it's at .55V, I looked for vacuum leaks and all of the lines still look brand new. Spark plugs, wires, cap and rotor were done exactly 1 year ago. About 4 years ago, I replaced the EGR.

When I start the car it starts fine and if I leave the AC off, it idles normally. Turn it on, it starts bog and then slow goes from 600 rpm to 500, to bogging between 5 and 1 and then stalls. When I pull out of my community onto the main road it's sluggish as hell with the AC. It takes forever to reach 60. With it off, it flies like a muscle car should! When I do drive with the AC, it feels sluggish for the first 15 minutes or so. Then the car just kind of peps up and feels normal.

Vinscully50

Update. Yesterday I drove to my parents house, 3 miles down the road. It wanted to stall a little bit on start up but I revved the engine and it stay alive. It wanted to stall again at the entrance of their subdivision. Later when I left their house, it took me a good 5 minutes of starting it and it stalling before it ran somewhat smooth. I got it up to 60 no problem, but then it stalled at the light. I got it started and in my community and it stalled at the gate, I started it again and it stalled in my driveway.

This morning it keeps stalling no matter what I do. When I step on the gas it vibrates a ton. It shudders a lot right before it dies:

Vinscully50

I got some data from TurnerPro RT can anyone tell me if anything looks off?

Kincer

It might be just me but it sounds a little sluggish when it's trying to start, have you checked your timing? How old is your battery?

Vinscully50

I think it might be the battery. The battery was reading at 12.4V until I managed to get the car to run smoothly and took it for a long drive. Now it's at 12.7V.

Vinscully50

Updates. So I unplugged the MAF again and while it ran rough it wasn't stalling. My MAF is only 4 years old but it's a remain. So I purchased a brand new Delphi unit. With the AC off the car is running like a champ. However, with it on, when it hasn't warmed it it kind of gives a rough idle at first (but levels out). But it's sluggish off the line with the AC on, it hesitates and it still feels a little sluggish up to about 70. With the AC off it's fast.

Timing is at 6* BTDC and all ignition components are about a year old. So this is my new problem now. But it's a huge improvement compared to where I was.

Kincer

It's noteworthy that a weak battery can sometimes wreak havoc on these cars, doesn't sound like the issue though, probably, mine was giving me some weird issues and I went ahead and got a new battery because I had no idea how old it was so I figured it couldn't hurt, amazingly it's been running much better.

It's possible that maybe there's bad bearings in the AC compressor causing more drag than usual, just a thought, again could lead back to battery as well, if your battery is weak and alternator isn't keeping up with extra power needed with the AC running.

Vinscully50

The battery is 2.5 years old and I'm in Florida, so it's getting close to end of it's life. I'll probably try a new battery just to see what happens. I know last few times my battery was getting near the end of it's life my car started doing weird things. One time it kept popping the gauge fuse and I couldn't find out why until I replaced my battery. Another time my fog lights wouldn't come on and my "Brake" indicator light wouldn't shut off.
It could be bad bearings, I'm 99% my compressor is original. It was first converted to R134 8ish years ago. But I'm sure it's original.

Reddragon88gta

I have noticed that my car doesn’t run the same with AC on as well, but more noticeable when engine is cold. Similar to you it sputters and feels weaker but it doesn’t stall. The car runs much better when warmed up with AC on…I haven’t been able to figure it out and am to the point I think it’s a old car quirk.

Vinscully50

I wondering if it's what the other guy said and it's the AC bearings getting old. A few years ago, the AC on didn't make a difference. Now it does.

Reddragon88gta

My compressor is maybe 2-3 years old new AC Delco but I live in upstate NY so I don’t run it a ton but it comes in handy once in awhile.

If yours is the original Harrison it might be on its way out. Maybe mine just hasn’t broke in all the way yet lol

vinny R

Is your "idle up" circut working. Not sure if that is the correct name but when the AC is turned on the computer will up the idle to compensate for the extra load on the engine. When you first start the car with the AC off and the idles settles if you turn on the AC the idle should jump up, especially when cold. I had this problem with an old truck and it would never be right with the AC on when it was cold. once warmed up it seemed fine.
Not sure if this is your issue but something else you can check.

Vinscully50

That could be the case. I'll fool around with it later. The idle up isn't the IAC valve is it?

vinny R

Yes, the computer will open the IAC and I believe add fuel as well.

i88aGT

Here are some more things to explore.
1. Does your dash voltmeter not work?
2. Adding to bearing theory, alt also has bearings. How's the belt doing when this is happening?
3. For the "idle up" tip suggested, didnt see that term in manual. But I did see A/C ON Signal, ECM B8. In 88 GM manual under TPI it is described as such: "This signal tells the ECM that the AC selector switch is turned ON, and that the pressure cycling switch is closed. The ECM uses this to adjust the idle speed when the AC is working. If this signal is not available to the ECM, idle may be rough, especially when the AC compressor cycles. The voltage at ECM terminal B8 should equal battery voltage on a C60 system and about 5v on a C68 option, when AC is requested and the pressure cycling switch is closed."
4. I think u have a charging problem (batt and alt) and maybe some funky wiring, cuz you have sluggish AND rough/stall symptoms. Bad charge works for both. Like instead of AC causing symptom, could it be the new fan load? But if you wanna look into the AC more it also suggests under ROUGH, UNSTABLE, OR INCORRECT IDLE, STALLING: check for ac pressure too high, overcharge, or faulty pressure switch. (Note, i think pressure switch is opposite 86 vs 88, N.O. vs N.C. if that makes a difference?)
Hope that helps.

Vinscully50

Updates. I did notice that sometimes when my car is cold and I first turn on the AC, the compressor has a very mild squeal to it. It's not belt sequel but like a cold metal squeal. It goes away either when i turn my AC off or after it warms up. I wondering if that is bad compressor bearings.

My volt gauge even after replacing it a few years ago never seems to read accurately. But fooling around with the multimeter my battery has been at just over 14v when the car is running. It seems to be around 12.5v when the car is off. However, earlier today, I had to tap my starter after I went for a drive. I left my car in the parking lot, came back out 30 minutes later and turning the key did nothing. Lights worked, gauges worked but no response from the starter. I put my multimeter on my battery and it was at 12.5v. So I grabbed a ratchet extension and a hammer, give it a good tap and she fired right up. So that might explain the hard starts.

350Iroc89

iTrader: (3)

Resting voltage doesn't mean much. Try a load test on the battery with the car off.

Vinscully50

Ok the plot thickens. So I drove my car a good 80 miles or so round trip. On the way home, I stopped at Wendy's. I had the windows down and my AC was off. While waiting for my food, my car stalls and dies. No sputter, no weird mechanical noises, it just died like an EMP hit (You old guys might remember the scene in the Day After). Anyway, I try to restart it and the fuel pump primes, indictor lights come on, head lights are on but nothing. I know the starter is bad, so I try tapping it and nothing. So a good samartain helps me push it into a parking space.

I grab the multimeter and temp gun. Temp is at 190 (temp is normal inside, overflow tank is just about the full hot line), Battery reads 12.5. So I keep trying. Mysteriously after 30-45 or so minutes car fires up. I drive the last 10 minutes home. I leave my car in my driveway and no issues. It's idling normally.

However, when I put a mild load on the alternator such as pushing on my window buttons after they are all the way down, my headlights dim and my RPM drop from 850ish down to about 500. As soon as I let go of the buttons, headlights return to normal and RPMs rise.

I know that Alternator is 2 years old but it's a remain. I know the day I replaced it, I had 3 fail from NAPA and 2 from O'Reilly's fail before this 3rd one worked. I'm wondering now if it's on it's way out. I wondering if this is related to the AC-sluggish issue?

Either way, I'm heading to bed. I don't have a load tester, so I'll take the car to the autoparts store tomorrow and see if they can load test it.