Hello All,

I have a 1996 850 GLT wagon, 5 speed manual, n/a engine with dual climate control. The car has 315,000 miles on the odometer. Recently I have noticed that if I set both temperature dials at 60 degrees and set the a/c on "auto" ice cold air blows out of all the vents. If I increase the temperature on both dials to 66 degrees, hot air will blow out of the two vents off to the left of the steering wheel (I'm in the U.S. so the car has left hand drive). Also, once I raise the temperature to 66 degress, of the two vents located in the center of the dashboard (just above the radio) the vent on the left (closest to the steering wheel) will start to emit temperate air, not hot, but certainly not cold.

If I lower both temperature dials back to 60 degrees, cold air will again blow out of all the vents.

Has anyone else had this experience? Any suggestions as to what is causing this problem? The a/c evaporator has been replaced a few times over the years and the a/c compressor has also been replaced. But as I mentioned, I do get cold air, just not out of all the vents. Thanks to all who reply.

Hugh

Hello All,

I was just notified by my independent garage that one of the temperature sensors located in the ceiling by one of the two handles was defective. It was preventing the a/c vents from operating properly. I had cleaned out both sensors before I dropped my car off, so the sensor was defective and was not working due to debris.

Thank you to all who replied. I hope we all benefited from this exchange of information. I certainly did and I am thankful. By the way the sensor is a dealer item and not cheap: $90. But what are you going to do?

Hugh

That is what junk yards are for! The sensors usually get crushed with the rest of the shell because people don't know they are behind the grab handles. I am surprised that you didn't get yellow blinking lights telling you of an error.
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My name is Klaus and I am a V♂lv♂holic

Hello All,

I cleaned out the two cabin sensors. I also started the engine with the dual climate control setting in "auto" with the a/c button on and the "rec" button off and the lights for the "a/c" and "rec" buttons did not flash together.

Still, the vents to the left of the steering wheel blow hot air and the vents to the right of the steering wheel emit temperate air when the a/c is on. The remaining vents emit cold air. If the cabin sensors are good and the there is no stored code in the climate control system, what else could be the cause of this problem? Thanks to all who reply.

Hugh

Now we are getting somewhere. Because the system works when the driver's temp is set to minimum and you get cold air, I suspect that the temp control in the ECC unit may be bad.

There are a number of temp sensors, but if one of them fails, there is an error set and the lights should blink at start up.

A junk yard unit might be reasonably priced, 1996 and 1997 both fit, and easily fitted to your car. A reasonable price is $30-50. Just make sure the unit is identical to yours, a variable blower speed and temp numbers.

If the damper on the driver's side were broken and not moving, the heat/air mix would remain the same regardless of the temperature setting.
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My name is Klaus and I am a V♂lv♂holic

Klaus,

Thank you. I'll share your comments with my mechanic.

Hugh

Since your AC is blowing cold, it sounds like you are either getting outside air or heater core air through these vents. So it would seem that the problem is the result of the various doors in the air system not being in sync with the ACC. In other words, the ACC is telling them to open/close incorrectly. I agree with Klaus' last assessment to try another ACC unit. My sons 1994 940 had a similar problem, so I went to the local pick-a-part and found unit from a donor and re-installed it...IT WORKED.

Just a hunch...On the left side of the 2 top center vents, there is a "MIX" adjustment wheel. Rotate the thumb wheel all the way down and see what happens.

Good luck!

Hello Most Unusual,

I took your suggestion, and swapped out the ACC unit from my other 1996 850 which is also equipped with the dual climate control feature. The vents on the "problem" car continued to malfunction even with a different ACC control unit. Meanwhile, the "non-problem" car's a/c worked perfectly.

It seems that the problem is one or more of the motors which open and close the a/c vents don't seem to be working properly. I'll have this confirmed by my mechanic. Thank you and everyone else for your suggestions. They were very helpful to me.

Hugh

Thanks! The "mix" wheel adjustment is set to let in the minimum amount of outside air into the cabin. I'm going to follow up on your suggestion and Klaus': I have an identical '96 850 wagon with dual climate control. I'll switch the ACC unit from the car that is not experiencing problems with the a/c.

My mechanic mentioned to me today that the problem may be due to the electric motors that are supposed to open and close vent flaps no longer working properly. Because of the cost, you typical get replacement motors from a salvage yard.

Hugh

Yes, you could solder pins onto the wires then insert them into the connector. Here is the website where you can buy the male connecter. It cost $5 and makes the job so much easier. I bought item #1000.

http://www.carplugs.com/products.html

When looking at the connector from the drivers seat, the top left is pin 1 with pin 8 on the top right. The bottom row has pin 9 on the left and pin 16 on the right.

Pin 16 is +12 Volts
Pin 4 & 5 are ground. I used pin 4
Pin 6 is for the climate control
Pin 13 is for the cruise control
Pick any one of the wires coming from the sockets to wire to pins 6 and 13. The socket you pick will then be wired to the ether climate control or cruise control. My socket 5 is empty.

I haven’t been able to get to the ABS, SRS, seat computer, instrument panel seeing that there all on pin 7 with the automatic transmission computer. I trying to figure how to get the mileage of the 96 like on the 95 cars. If one knows how to talk to them, that be nice to know. I hope helps.

Hello All,

I took the advice previously given and cleaned/blew out the two openings where the cabin sensors are located just under the handles located on each side of the car.

Then to be "pro-active" I went to my other 1996 850 wagon (the a/c is working fine on this car)to clean out the two openings. Low and behold it didn't have the openings in the headliner for the temperature sensors. This car was built in September of 1995 (as a 1996 model). My other 850 wagon which has the a/c problem previously described, was built in March of 1996 as a 1996 model.

Question: Is it possible that my earlier manufactured 850 wagon came from the factory without the two cabin sensors, which were subsequently introduced later on during the manufacturing year?

Thanks to all who respond.

Hugh

Does your other car (w/o sensors) have ACC (auto climate control) or no climate control? I don't believe that my 95 GLT wagon w/o climate control has the sensors either. Can't check since my car isn't here at the moment. The sensors may only be for climate control cars.

My other 850 without the sensors, also has "dual climate control" just like the car that does have the sensors.

Hugh

I built a code reader for my 96 & 97 850s. I got the A OBD1 box from a 95 850 from junk yard. Then bought a OBD-2 connector off the internet to plug into the car’s OBD port. I connected the wires on the A box as follows:

Yellow / violet wire to pin 16 +12V
Black wire to pin 4 ground
Any socket you want to pin 6 for the climate control
I also wired pin 13 for the cruise control to a socket

The box will then works just like it does on a 95 850

Thank you, though I confess I don't think I have the skills to make the repairs you have outlined.

Hugh

This is good news! Not having a Box in hand, would it be possible to solder pins to the wires and just insert said pins directly into the OBDII port?

Some of us are not electrically inclined, so we need to know where to start counting holes. Use facing forward in the car as a reference, so that #1 is the bottom left or the top left???

There is a simplified wire diagram somewhere that shows a wire with an LED and on/off switch that is supposed to do the same thing. The problem is, that diagram does not show which port is for the A1, A2, A6, etc, much less for the B ports.

Klaus
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My name is Klaus and I am a V♂lv♂holic

Do yourself a favor, before starting the engine turn the blower speed to auto, vent control to auto, AC on and recirc off. Start the engine and see if the recirc and AC switch blinks yellow for 20 seconds. If so, there is a fault in the system that can be read by a Volvo scanner.

Usual faults for the 850 are the cabin temp sensors behind the forward grab handles above the side windows. They get dirty and the temperature readings can be faulty. I have taken a toothpick to clean out the dust bunnies lurking within and delicately cleaned off the fan blades. A vacuum cleaner helps suck out the dirt.

Moving the temp dials to the coldest setting, not my favorite position, turns off the temperature readings from the cabin sensors and blows only cold air.
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My name is Klaus and I am a V♂lv♂holic

Klaus,

Thanks! Do you think a fault in the system or a dirty sensor could cause some vents to blow hot and others temperate air?

Hugh

BTW, never drive with the blower turned to 0/off. The computer case needs to have air drawn through it, and the blower does this. It also keeps the blower rehostat cooled off.

ECC codes can only be read by the Dealer. Most codes refer to the cabin temp sensors(2) or the recirc flap breaking.

Klaus,

Thank you for your advice. I'll follow up on it this evening.

Hugh

The cabin air temp sensors tend to collect dust over time that coats the thermistor. They're located behind the grab handles above the front doors. There's a small hole there that allows a small fan to suck in a small amount of air past a small thermistor. Try blowing some canned air into the holes to clean out any dust. DON'T stick the canned air nozzle tube into the hole more than 1/8" or you may damage the thermistor.

Thanks! Do you think a dirty sensor could cause some vents to blow hot and others to blow temperate air?

Hugh