Hi all I have a 1997 volvo 960 and it experiencing some problems with the A/C the symptoms are that after having the A/c on on cool while running it just stops blowing cold air i think it does it more on high tempetures. but it just stops turn it off and wait starts blowing cold but then boom stops blowing cold air. im not thinking is the compressor cus it blowing really cold when its working. Also when u accelerate the car it stops blowing air from the main vents and start blowing from the floor vent,, i've had several volvos with this issue i guess its a common problem with this cars. anyhow any thought or ideas would really helpful on how to start troubleshooting the A/C.. thanks in advanced

 

1- What are your freon charge numbers?

Second symptom -- when accelerating airfow switches from center vents to low vents -- that sounds like a vacuum bellow /actuator that moves air-doors is not doing its job at low vacuum. There are located behind the glove box.

 

I guess is full on Freon cause its really cold the air, but when u are driving in highway or any road it just stops blowing cold air.. and then if u wait it start blowing cold again anf then again stops. i havent check the freon levels cus the car gets really cold but i will do that tommorow. if it good on freon what do you think the problem might be?

what should i do as to the second symptom?

 

Pressure goes up and down, and if the charge is low, it can fall below the threshold, and the pressure sensor cuts the compressor off.

If Freon is ok, then you would need to go through diagnostics for the pressure sensors (low and high, cut-in, cut-out). Another option is the acceleration sensor failure too.

Above all, Climate Control Units are known to have problematic soldering points.

About the second problem: you can diagnose the vacuum actuators. You can download the instructions at k-jet.org

 

What do you mean by the acceleration sensor failure and the climate control?

 

Some 960s have an option of an acceleration sensor, part of the AC circuit. It on the right front subframe, close to the bumper.

"Climate Control" Unit is the unit with buttons that you push and ***** that you turn on the dash, above the radio.

 

I know the climate control but what is exactly that goes wrong with it

 

Some solder-joints crack and need re-soldering.

 

I have a 97 960. I live in Texas so it is very hot in summer. When it is hot and the car is under the sun for a while, the vent control does not work. I have checked the vacuum actuator when the vent control works, It does change vent directions (face, bottom, defrost, etc). I have not got a chance to test the vacuum actuator when it does not work as this is my wife's car and when I check it, it always works.

Any idea what could be the problem? Any help is appreciated.

 

If the direction of air changes, e.g. from the center vents to the feet's vents, while you/wife are accelerating, that's a sign of the vacuum leak. Vacuum is low at acceleration / WOT, and high at idle or closed throttle (foot off the gas pedal).

Another thing that goes bad is the vacuum check-valve, that is one of the two valves (# 10) in this diagram, the one that goes to the vacuum tank (# 6):

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These 2 valves are located inside the engine compartment, next to the firewall (passenger side, below the windshield wiper):
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Henry10, thanks for your quick response. The problem is not changing vent direction while driving. Rather, the problem is that sometime vent only goes to foot even though air control points to the face position. This usually happens at the beginning of driving after the car is parked under the Texas summer sun for a while.

 

Sometimes, ECC (Electronic Climate Control) Unit or the Vacuum Solenoid Controller can develop tiny cracks at the Board. Re-soldering these cracks fixes the problem. Use this guide to diagnose and fix the problem Heating and Air Conditioning

 

Thanks Henry10. I re-soldered the ECC sometime ago so I think it is ok. I will re-solder the Vacuum Solenoid Controller this weekend.

 

Since sun's heat affects the operation, I would also re-visit ECC's board with a magnifying glass.

 

I re-solder the Vacuum Solenoid Controller today. Now the vent control works. I took a couple of pictures for your info.

After taking out the under cover on the passenger side, you will see the Vacuum Solenoid Controller next to the ball-shaped vacuum storage as shown in the first picture. The second picture is a close shot of the VSC.

 

Hi Folks-

Having similar problems with my 960 AC. The main issue is no air flow from vents under acceleration. Done quite a bit of reading on this forum and various others, and I have checked for vacuum leaks under the hood, including check valve operation- all seems fine. One site recommended disconnecting and plugging the yellow vac hose- also did not work. Checked vac cannister- there are only 3 hoses going to it, and they seem fine. Did not see any cracks in the can. Since I do get flow from the vents at idle, it doesn't seem to me that it would be electrical- more of a vacuum problem. Any thoughts on what I might have missed? Also read somewhere that the S90 was "designed" to cut out on acceleration- seems odd that would be the case, but can anyone verify? I don't remember mine doing that before. Any help is appreciated. Texas sun is brutal these days..

 

Yes, Compressor is cut-out when in WOT (wide-open-throttle), but not necessarily in any acceleration. It is a common problem that airflow will change direction when accelerating. For example it will flow out of the lower vents. Is this what's happening, or is air flow stopping altogether?

 

Hi Henry10-

It is definitely not WOT- it's basically ANY acceleration- as in from a stop light or stop sign, or going up the hill in front of my house. Pretty sure the air is not re-directed, it sounds like the fan is stopping altogether.

 

When accelerating vacuum is reduced. IMO these cars have an undersized vacuum reservoir. So this problem should only occur under hard acceleration.

If it happens at any acceleration, one of the vacuum bellows is bad, and is not holding the door open.

The sticky at the top has info on vacuum diagram, and System Diagrams, which shows lines, bellows, etc.