stalling with ac on. 1992 960
stalling with ac on. 1992 960
I have a 1992 960 that has a stalling problem with the ac on when stopped at a light. AC will make a hissing sound from the vents then the compressor comes on and the tach drops and comes back up over and over till the car stalls usually after three times. The car will restart without any problems. Car does not have this issue with the ac switched off. It idles at 650 rpm. Replaced fan relay recently and warning light stays on untill fan reaches temp 12:00 position then warning light shuts off. Cleaned IAC and it seems to be fine. Could it be the two stage fan not cooling off causing high pressure shut off cycling?Car runs perfectly at speed very cold AC. I live in Florida and shutting AC off at all stops is a real pain. What could it be?
What warning light is remaining on until the engine is at operating temp?
It could be a few things, each one would need to be ruled out. These come to mind, others may be able to add to this.
1. Your high pressure switch is not functioning correctly.
2. Your idle speed motor is dirty or needs replacement. Idle speed is not being maintained.
3. The signal sent when the a/c is turned on is not getting to the computer. The message to increase idle speed is not being received.
4. Your compressor is faulty.
Having my car for this long and living in the rust belt, all of the connectors under the hood(bonnet) are very prone to corrosion. So prone, it should be a fall and spring maintenance item.
DanR '94 964 332,000 miles (98,000 on the new engine)
It could be a few things, each one would need to be ruled out. These come to mind, others may be able to add to this.
1. Your high pressure switch is not functioning correctly.
2. Your idle speed motor is dirty or needs replacement. Idle speed is not being maintained.
3. The signal sent when the a/c is turned on is not getting to the computer. The message to increase idle speed is not being received.
4. Your compressor is faulty.
Having my car for this long and living in the rust belt, all of the connectors under the hood(bonnet) are very prone to corrosion. So prone, it should be a fall and spring maintenance item.
DanR '94 964 332,000 miles (98,000 on the new engine)
Ok. Topped off the coolant tank and low water warning light went off. I thought it was fan related. What would make me belive a Volvo warning light didn't mean it ment it was a warning.DOH! I put on the extra iac I had which was a little larger probably from a 1995 temporarly and went for a stop and go ride. Idle was faster about 800 rpm and as soon as it reached temp it stalled when at a stop. I cleaned my old iac and put back on. Started again put ac on and waited for stall. When it started i reved to 2500 rpm and wached tach. I could feel ac compressor kick on and car revs dropped like it wanted to stall. It looked like the check engine light glowed breifly. I did this for about 3 min. and it went away. It fan smooth. I brought it back to idle and it behaved normal. Ac came out cold did not stall and ac compressor did not cut out. Set at ACC at aut-aut and 72 deg.rec light went off and fan speed dropped cabin temp seemed ok. I didn't hear hissing from vents. Could it be the ecu trying to shut down? Or could it be compressor locking up. It has me puzzled.
Ok. Topped off the coolant tank and low water warning light went off. I thought it was fan related. What would make me belive a Volvo warning light didn't mean it ment it was a warning.DOH! I put on the extra iac I had which was a little larger probably from a 1995 temporarly and went for a stop and go ride. Idle was faster about 800 rpm and as soon as it reached temp it stalled when at a stop. I cleaned my old iac and put back on. Started again put ac on and waited for stall. When it started i reved to 2500 rpm and wached tach. I could feel ac compressor kick on and car revs dropped like it wanted to stall. It looked like the check engine light glowed breifly. I did this for about 3 min. and it went away. It fan smooth. I brought it back to idle and it behaved normal. Ac came out cold did not stall and ac compressor did not cut out. Set at ACC at aut-aut and 72 deg.rec light went off and fan speed dropped cabin temp seemed ok. I didn't hear hissing from vents. Could it be the ecu trying to shut down? Or could it be compressor locking up. It has me puzzled.
When you activate the a/c at idle, after several seconds your coolant fan should start. Is that happening?
If not, check your high pressure switch, that contols the coolant fan. Tonight, I'll look at the wiring diagram that names all of the a/c swithes. They are located just inside the grill, on the left side, three in a row.
To me it sounds like your compressor is very hard to rotate, or the pressure is built up and making it hard to turn. I had two pressure switches fail at the same time. The one that senses for the coolant fan to turn on, when that was bad the cabin warmed any time the car was still, unless the engine it self requested the coolant fan to turn on for the engine management side. Normally anytime normal operating pressure gets to a certain point the coolant fan is suppose to run, such as when idling or while at a stop light.
I figured out the three switches but don't know which one is which.
One is high pressure, cuts the compressor. One is low pressure, cuts the compressor. The other is operating pressure, turns on coolant fan when a certain threshold is attained ie, at a stoplight.
The other switch that failed was the high pressure switch. When that went bad, it just blew the high pressure hose to the fire wall apart. That one was easy to tell. But maybe your system is not fully charged and therefore never gets to the pressure needed for bursting, just gets high enough to cause the compressor to nearly stall.
I also know this system is very sensitive to the amount of freon, to get things right, it should be vacuuated and then filled by weight.
Hope you get this figured out.
DanR '94 964 332,000 miles (98,000 on the new engine)
If not, check your high pressure switch, that contols the coolant fan. Tonight, I'll look at the wiring diagram that names all of the a/c swithes. They are located just inside the grill, on the left side, three in a row.
To me it sounds like your compressor is very hard to rotate, or the pressure is built up and making it hard to turn. I had two pressure switches fail at the same time. The one that senses for the coolant fan to turn on, when that was bad the cabin warmed any time the car was still, unless the engine it self requested the coolant fan to turn on for the engine management side. Normally anytime normal operating pressure gets to a certain point the coolant fan is suppose to run, such as when idling or while at a stop light.
I figured out the three switches but don't know which one is which.
One is high pressure, cuts the compressor. One is low pressure, cuts the compressor. The other is operating pressure, turns on coolant fan when a certain threshold is attained ie, at a stoplight.
The other switch that failed was the high pressure switch. When that went bad, it just blew the high pressure hose to the fire wall apart. That one was easy to tell. But maybe your system is not fully charged and therefore never gets to the pressure needed for bursting, just gets high enough to cause the compressor to nearly stall.
I also know this system is very sensitive to the amount of freon, to get things right, it should be vacuuated and then filled by weight.
Hope you get this figured out.
DanR '94 964 332,000 miles (98,000 on the new engine)
I wonder if your throttle plate is set correctly? Maybe it is set now just to the end of the limit for the idle valve. You turn on the a/c and the idle valve is already at it's limit. This just a guess, maybe a throttle cleaning and resetting the throttle plate might help.
Or maybe the throttle cable from the gas pedal is not letting the throttle to close normally. The cable should have a small amount of slack at idle position. Or it could also be throttle sensor. Or the cruise control is not slack either, look for some interference with the throttle assembly.
I am afraid that is all I have for you.
DanR 332,000 miles (98,000 on the new engine)
Or maybe the throttle cable from the gas pedal is not letting the throttle to close normally. The cable should have a small amount of slack at idle position. Or it could also be throttle sensor. Or the cruise control is not slack either, look for some interference with the throttle assembly.
I am afraid that is all I have for you.
DanR 332,000 miles (98,000 on the new engine)
You might have something there. My cruise is not functioning. I tried lifting up on brake pedal but it didn't do anything.I was thinking of cleaning throttle plate. I did put a new tps on when I replaced belts as I have over 150,000mi just as a precaution. I will get to that this weekend. I think there is a setting listed in brickboard. I will reset tps when adj throttle plate too. What do the three switches do at the bottom of the radiator? From left to right as you face the car? I will order the one you mention that is not controling fan as this seems to be working. Many thanks again. I hate to let this problem spoil such a fine car. Cleaning the throttle will probably make it run better at idle.
If your cruise is not functioning maybe you have poor vacuum and have an intake gasket leak?
I would go over that throttle work first though.
The switches according to my book, facing the front of the car.
Left = pressure switch
middle = pressure switch
right = pressure switch coolant fan full speed.
There is no description about their use in my manual because it is for engine diagnostics, so the first two are only about the a/c system
I am guessing but think the first two are either, high pressure and and running pressure.
If you take an ohm gauge, the switches themselves should have no resistance. The also screw out as they are on schrader valves.
Dan
The low pressure a assume is the one on the drier up by the firewall.
I would go over that throttle work first though.
The switches according to my book, facing the front of the car.
Left = pressure switch
middle = pressure switch
right = pressure switch coolant fan full speed.
There is no description about their use in my manual because it is for engine diagnostics, so the first two are only about the a/c system
I am guessing but think the first two are either, high pressure and and running pressure.
If you take an ohm gauge, the switches themselves should have no resistance. The also screw out as they are on schrader valves.
Dan
The low pressure a assume is the one on the drier up by the firewall.
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