1996 Volvo 960 Air Conditioning Problems

[Volvo 960]

I know that most people have already asked these questions, but everything I read doesn't quite match my problem. So if any of you would be so kind as to provide me with any tips or information, I'd be most appreciative, because Florida weather REQUIRES A/C.



I have a 1996 Volvo 960. The A/C vents for most of the time, DO NOT BLOW AT ALL. I can switch to any setting, even defrost, and it won't blow either. Once in a while, if you get the car to about 40-45 MPH, it starts to blow, but once you stop, it shuts off. Not hard mind you, but it does blow. And sometimes when you go over a bump in the road, it'll come on. I already have charged the A/C system with freon, but it does have a leak I know for sure, I've had to charge it about 3 times since I've owned the car in early 2003. Also of note, sometimes when you accelerate VERY quickly from a light, you get a blast of Air, when before(when a/c blew) it did exactly the opposite, and shut off until you let the load off the engine.


Please, any help would be appreciated. Thanks for reading.

[Kmaniac in California USA]

It sounds to me like you have a bad vacuum leak, although not as bad as the one I had in my Volvo. From your description, your car is generating some engine vacuum for the vent controls, but only under certain, "high vacuum" conditions. I don't know if you are a DIY (do-it-yourself) person or reliant on mechanics. But I suggest either you or a trusted mechanic performing a vacuum load test on your vent controls.

You should be able to find two, small-diameter plastic tubes passing through the firewall behind the engine. One will go to the heater control valve. The other will tee into a 3/8-inch diameter vacuum line. Disconnect the small vacuum line at the large tee. Connect a hand held vacuum pump to this line and pump up a vacuum in the line. The system should be able to maintain a constant vacuum once the controls have adjusted to the setting selected on the dashboard. If not, the leak is under the dashboard. You should draw a vacuum into the system for each vent control setting. Then, for each setting, turn the ignition to "on" and turn your fan switch on "4". The air should blow from the vents selected. If not, then the problem is with the vent controls under the dashboard.

Below is my experience, posted here previously. My problem was in the engine compartment and not under the dashboard. I hope this helps. If you have further questions, please reply. I can supply digital pictures of what to do if you like.
See Below:

I don't need help with this one because I figured it out myself. However, others may learn from my experience.

Shortly after I purchased my car, I discovered that the A/C vent controls did not function. The fan switch worked well, but I would only get air flow through the Defroster vents no matter what vent position I selected. Also, air would be slightly warm no matter the position of temperature control. I also discovered the A/C belt removed from the compressor and the A/C clutch wiring purposely disconnected.

The previous owner had the car serviced at an independent Volvo garage in the "People's Republic of Berkeley", California. Two years ago, the shop discovered that the controls did not work and quoted $250 to repair, though they didn't state why they would not function. On the same repair bill, they replaced the temperature control valve and charged a fee to remove the A/C belt. Then, ten months ago, they replaced the temperature control valve, again, for whatever reason.

I quickly discovered that these controls required engine vacuum to operate. I found two vacuum tubes that passed through the firewall. One went to the heater control valve. The other to a tee in a large diameter vacuum line. One end of the large line attached to the intake manifold. The other end went somewhere under the left side of the car. I looked under the car and found the line attached to a long, cylindrically shaped, plastic tank, mounted forward of the front crossmember.

I disconnected the main vacuum line from the intake manifold and plugged the tap. Then I disconnected the vent control vacuum line from the tee, attached a hand-held vacuum pump, and pumped down a vacuum in the vent controls. I quickly found that the vent controls operated normally as long as I kept a vacuum on the controls. This told me that I had a vacuum leak somewhere on the main vacuum line.

I went back under the car and unbolted this plastic tank from the undercarriage. It is held on by three bolts. Once I got it out from under the car, I easily saw the large crack that traveled half way around the far end of the tank. No wonder the vent controls did not work, there was no vacuum in the line. Not only that, the car had a major intake vacuum leak that went undiagnosed for over two years, and the independent mechanic that had serviced the car all that time, saw the clues, but was too blind to figure this out!!

This tank is positioned in such a manner under the car, that it is the first thing to be hit by large debris on the roadway. It appeared that the crack was cause by blunt force trauma from road debris.

The purchased a new vacuum tank from my local Volvo dealer for $47. Once installed, the vent controls worked like new. I then replaced the A/C compressor belt, reconnected the clutch wiring, and now the A/C blows 40 F air in the coldest position. I don't think I would recommend that independent Volvo garage to anyone I know.

So, if your vent controls stop working, be sure to check for vacuum and the condition of this tank before trying to take apart your dashboard controls.

[tedpnyc]

I had a similar experience with the ECC on my '95 965. There would be plenty of cold air from the dash vents at steady-state and coasting, but the airflow would drop to nothing on uphill climbs. The vent flaps are held in place by vacuum. The default /fail-safe position sends air to the defroster and floor. If you have a leak in the vacuum system, there is normally enough vacuum generated from the intake manifold to keep the distribution flaps positioned correctly. Open the throttle for a long hill, the vacuum drops, and the flaps revert to their default position. The cold air is still being put into the car, but it is directed to the windshield and your feet, and not to your face. Also, the recirculate flap is held by vacuum. Lose the vacuum, the system reverts to the default of taking in outside air. All of which combines to lead you to think the ECC has failed, since there is no more cold air from the vents. At some point, Volvo moved the vacuum reservoir from behind the front bumper (where it could get damaged) to under the glove box, where it is safe, but impossible to reach.

The hoses that supply vacuum to the system are connected to the ECC as mentioned above, on the right side firewall, next to the receiver-dryer (silver cylinder with hoses attached to it). My '95 960 has three hoses. One leads to the heater control valve, which is mounted on small coolant hose, on the firewall. One supplies vacuum to the interior thermostat, the third supplies vacuum to control the ECC flaps.

First rule - only disconnect one hose at a time!! That way, you don't have to worry about reconnecting to the wrong place.

Put the hood fully vertical - it will make your life easier. Start the engine and let it idle. Disconnect each of the hoses in order. Two will have vacuum - you will hear air hissing when you disconnect it. The one without vacuum leads to the heater valve. Put it back and leave it there. You now have two vacuum hoses.
Now to isolate the hose that controls the ECC. Put the ECC on manual, direct the air to the dashboard vents, fan on high, and recirculate. Lower the right-side window, so you can feel the air blowing on your left hand as you manipuate the hoses with your right hand. Disconnect one hose, and wait. If you disconnected the hose that controls the ECC, you will feel the air blowing on your left hand diminish, and you will hear the air start to enter the air intake at the base of the windshield. It takes about 15-20 seconds for the flaps to revert to their default positions. If nothing changes, the hose you disconnected supplies vacuum to the thermostat.

Now that you have found the correct hose, you need to find the leak.

First, the check valves.

The check valves look like the top of a golf tee. One side is black, one side is white. These are known to fail. Very important to note which side points in which direction when installed. You can test it by blowing a bit of air through each side. One direction will pass air, the other will not. If it allows air to pass in both directions, it has failed. Find a replacement at a junkyard.


Check valves ok?

Leaks elsewhere:

Remove the hose from the connection on the firewall. Quickly put your thumb on the end of the connection, to keep air from leaking through the exposed opening. Wait. If you have a leak elsewhere in the system, the flaps will gradually revert to their default position, but it will take a while. It took about 90 seconds for my car to revert. This meant that I had a leak somewhere under the dash. Should you waste hours trying to find the leak? absolutely not. Just add a backup vacuum reservoir. GM used vacuum controls on their AC systems for years. Any GM car manufactured before the late nineties should have one. The GM vacuum reservoir is a black sphere, about the size of a melon. It has one hose attached to it. I got one at a junkyard for $5. Use a t-fitting and some new vacuum hose and splice the reservoir into the ECC control system at the firewall. Make sure you splice in the reservoir on the ECC side of the check valve, not the vacuum supply/intake manifold side. I mounted the reservoir right over the battery with an M6 bolt. Did I fix the cause? No. Does the a/c stay on the dash vents during those long gradual hills? Mostly, and better than before.

[bluewater]

I wish I saw this post before I took out the AC controller and tried a few other thing to fix this problem. I live in Texas so the summer is very hot. Typically, no ac air flow during the hot weather. I have searched the internet and followed a few advices like re-solder the AC control unit. It turns out the the vacuum line connected to the firewall connector is lose. Tighten up the connection, now the the vent control works and cold air flows.

[davebutler]

Old post I know, but though I would add my experience.

My 960 is right hand drive, living in England as I do, but I should think stuff in my passenger footwell is stuff in a LHD footwell too.

My AC wouldn't send air where required, and the car gor really hot inside. I followed the very helpful advice in this thread, but to no avail. I did notice that the hot water valve was always open irrespective of any control positions.

It turned out to be a broken connection on the control block that directs the vacuum to the various vacuum solenoids.
How to diagnose?
Now mine works, I noticed the following.
Ignition on, but engine not running, radio off, fans off. Try and find somewhere quiet.

Listen in the passenger footwell, and turn the air direction control between settings. Should get a slight noise in the footwell a bit like someone lightly tapping a plastic box with a screwdriver. Same sound when selecting recirculate. If you then slowly turn the temperature dial all the way up (or down if it was up), at some point you will hear another tap, and then a whirring sound. The whirring sound is an electrically operated flap opening or closing the hot air path.

Getting all the taps and whirring? Then it's not the block - sorry can't help. If however, you don't get the volvo percussion symphony, then the next step is to check the control block.

Get you head in the passenger footwell, and look up. You will see that the plastic above the passenger feet is a large piece held in with some self tapping screws and plastic half turn faster near the door. Undo these, pull the cover away from the trans tunnel (some pop fasteners there), disconnect the footwell light, and remove the plastic cover. I removed the glovebox liner (two screws inside, and two clips just abovw the screws), which let in more light, but I don't think it is stricly necessary.

OK, now look in the area near the trans tunnel. The control block is made from goldish coloured steel, with a white plastic panel on it, held on with a further goldish coloured plate. There is green connector on the left with about seven wires, and a connector on the top with about eight what look like large wires in - these are vacuum tubes - multicoloured.

What I found was if you put the ignition back on, and jiggle the elctrical connector, you could hear the solenoids clicking on and off as the connection made and broke.

So remove the block - two selftapping bolts into the plastic of the ventilation system, remove the elctrical plug and remove the air tubes (I already had the plate off, but I dont think you need to do that)

On turning it over, and inspecting it closely under a bright light and a magnifier, I could see that the soldering on the main connector had broken. Resoldered all the connectors to be sure, reinstalled it and perfect. Put the car back together and now it works fine. My AC still doesn't work as there is a hole in the radiator, but here in the UK you need demisters more than AC which is nice to have for about ten days a year.

[billofdurham]

davebutler, welcome to Matthew's Volvo Site.

Old post or not it is more information to help those with this problem. Thank you.

Bill.

[960fasterthanmy940]

Try putting the recirculation button on.. I had a similar experience this summer (my 1997 960 is the first volvo I have owned with WORKING A/C!) My A/C was not working as described above when it was really hot, however if I hit the recirculation button - viola perfect strong cold air flows from the vents...

[edelmatt]

I'm glad I found this thread. My Volvo 240 (1990) had perfectly working air flow controls but at some point (I don't know when) they completely stopped working. Previously when I'd change a selection on the control head, I'd hear a vacuum sound while the flaps re-adjusted. Now when I change the settings, there is no sound and no flap movement.

Does anyone know, on the 1990 240, where the vacuum reservoir is? I've looked from the top of the engine compartment and really can't discern it. Also, I have two service manuals and neither of them reference this part, or have any troubleshooting steps for the vacuum system that controls the airflow.

Thanks again.