240 Stalls when A/C is on. (1992 240 GL)

Hey guys. New here, and to Volvo's in general. I picked up a 1992 240 GL a few days ago as I want to learn about working on cars. Lucky for me I discovered my first issue while I was driving it home! (TLDR at bottom).

I drove it roughly 4 hours home from where I bought it. Here is the timeline / issue that I experienced.

Pickup time:
Everything working great. Car is in great condition, literally almost everything works except the front right headlight. It's hot where I live, so I crank up the air to 3/4 and switch on the A/C Compressor. A/C works, and I drive away.

00:15
Stop at the gas station to top off gas, not knowing yet whether or not to trust fuel guage. Still no issues. Then hit the highway.

00:45
Been running on the highway at on average 75mph. All of a sudden, the car begins to hesitate. Feels like the car is accelerating an then coasting intermittently at about a 2-3 second interval. I hold the gas down praying to make it to the next exit, which I do. After getting off the exit, I stall at a stop sign. I start it back up and am able to get it in gear and putt it another 100 yards into the gas station.

I decide to turn off the A/C and let the car sit for a bit. No check engine light (and the bulb works). After about 15 mins, I start it up, and seems to be idling fine now. I put it in gear and drive it around the parking lot, seems to be running with no issues. I get back on the highway.

01:45
The A/C has been off, and the car has been running fine for the past hour. It's gotten a bit hot inside the car with the A/C off, and it also begins to rain, so I roll up the windows and put the A/C back on and turn the fan up to 2/4.

02:00
Same issue happens. The car begins to hesitate in the same way. I make it to the next exit, and it stalls out again at the stop sign. Pull off to the side of the road, turn off the A/C. Sit for 15 mins. Car starts back up, and I continue the drive.

04:00
I made it through the rest of the 2 hour drive with no other issues and luckily make it home. There is still no check engine light.

Therefore it appears to me that there is a direct correlation between the A/C running, and the performance of the engine. Anyone have any idea where I should start in trying to fix this? Thanks in advance! Super excited to be here.



TLDR: Engine stalls when A/C is on.

Odd...could be a seized compressor. Go try to spin the compressor (center) by hand.

ZVOLV said:

Odd...could be a seized compressor. Go try to spin the compressor (center) by hand.

Click to expand...

Diagnosis for a seized compressor that still cools the interior when on?

Sounds like a borderline engine and AC is the last straw.
Or, possibly, previous owner overfilled a leaky AC with too much refrigerant, and pressure building up stalls the compressor, domino to engine?
check AC pressures?
good luck

IDK. Maybe you have other issues and just can't handle the load. Maybe it's electrical. Tldr. Pull the belt off and see if it still does it?

Update:

Taking a closer look at the engine, I noticed that the PCV hose wasn?t even connected to the top of the filter. Ordered a new pcv trap and hoses and fuel prepump. I?ll replace those parts and clean the throttle body and iac valve, then check the a/c system pressure. And I?ll go from there? Sound like a pretty decent plan?

Yeah honestly to me this doesn't sound AC related at all. My incling is either you have a grounding issue, the TPS misadjusted/loosened itself or there's a vac leak that the loading and unloading of the compressor is aiding you being able to detect it.

My long shot is that the compressor is over filled or somehow not freely turning.

My logic here is... with the AC engaged the compressor clutch would be clicking on and off during that process. But the electrical signal stays powered. So if it ends up being something compressor related, why wouldn't it show up the whole time?

Also... the idle could just be mis-adjusted?

I may have found the culprit. After removing the fan shroud and the fan, a quick inspection of the belt tensioners leads time to believe that the one near the alternator is completely missing! What do you guys think? Could this have caused the problem due to belts slipping?

<s>

Yes, just the lock bolt is missing, however the belts seem loose. Could this have caused the stalling that I described in the initial post?

An alternator going out can cause stalling issues yes.

I will just add this note which is having the same symptom except ONLY at idle. Might or might not relate to this one. When idling, with A/C on, my 940 n/a 1994, will stumble, threaten to die, but picks right up. Happens every time the fan turns on. Measuring voltage at the battery shows that the voltage dives down to about 9 volts just as the electric fan is turning on. These d.c. fans really draw big current when they start and stuff that runs off the main battery voltage starts to malfunction until the main battery voltage returns to normal. In my case the IAC valve runs off the battery +. The computer cannot react fast enough to keep the idle up. The only solution I've come up with is to replace the d.c. fan with an electronic fan, fan control, etc. Might or might not be worth it.

Lazarus