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Car Forum / Volvo Cars / June 2004Volvo 940 air conditioning fan blow to floor when accelerating
My 1994 Volvo 940, 4 cylinder (not turbo) air conditioner is acting strangely. Normally, I set the air condition fan blowing from the front on dashboard onto the face of driver and passenger. When I accelerate the car, the fan switched blowing to the floor from the bottom and stop blowing from the front on the dashboard. All other electrical equipment seems to work. The vacuum advance seems to be working correctly. Can you tell me what is the problem? Thank you. Additional finding: After the local Volvo mechanic worked on the car for the last two days, they were unable to find the exact problem. When they jack up the car, the air conditioner and fan blower works well, both when engine idle and accelerate. So they concluded the problem is not the vacuum control system. Only when the car is on the road and accelerating, the air conditioner fan will switch from blowing from top dashboard, to blowing from the floor below. As soon as the car cease to accelerate in constant pace, the air conditioner fan blows normally from the dashboard. Strange? Any clue? > My 1994 Volvo 940, 4 cylinder (not turbo) air conditioner is acting > strangely. Normally, I set the air condition fan blowing from the front on [quoted text clipped - 6 lines] > The vacuum advance seems to be working correctly. > Can you tell me what is the problem? Thank you. >Additional finding: > [quoted text clipped - 9 lines] > >Strange? Any clue? Get an inexpensive vacuum gauge and hook it up with a tee to a suspected vac line under the dash. Place it where you can read it while driving. You may need to move it from one line to another to find the culprit. If it is a general vac fault, then select any line and adjust the various temperature controls until vac is fed to that line. The test drive and see if it dips when accelerating. if no, then the problem is one of the vac motors and its related hose and switching (I would assume) it the vac drops on all lines then the problem is in the vac system. ..at least that's where I would go from there. But don't follow me.. I'm lost! from Randy & Valerie __ __ \ \ / / \ \/ / \__/olvo 1993 960 Estate >Subject: Re: Volvo 940 air conditioning fan blow to floor when accelerating >From: ">Randy G. <> [quoted text clipped - 14 lines] >> >>Strange? Any clue? Sounds like a really good question for Car Talk. Where can I find Car Talk? "A. J. Young" <jgy2001-nospam@yahoo.com> opined in news:2jj9i1F12bj39U2 @uni-berlin.de: > Where can I find Car Talk? National Public Radio. Usually on Saturday or Sunday. Live is on Saturdays at 6pm, iirc. Website - http://www.cartalk.com/ OK, after another day of work by the mechanics, this is still our problem: When the car is not moving, everything works fine. Vaccum is fine. When the car is moving at 25mph or faster AND accelerating, the fan will switch from blowing from the top dashboard to below at the floor. As soon as the car cease to accelerate and at constant pace, the fan switch back to blow from the top. Volvo 1994 940 6 cylinder (no turbo) automatic transmission, air conditioning push button on/off switch without climate or temperature control. The fan seems to blow at same speed. The air-conditioner on or off has the same problem. >OK, after another day of work by the mechanics, this is still our problem: > [quoted text clipped - 11 lines] >The fan seems to blow at same speed. >The air-conditioner on or off has the same problem. Volvo 1994 940 6 cylinder...? I thought: 940 = 4cyl 960 = 6 cyl whadooeye know? As I mentioned before, it sounds like a control problem under the dash- one possible scenario: You have a weakly operating vac motor *1. When you accelerate the vac lessens just enough that this vac motor 'relaxes' and is closing one of the air-flow control doors. When you lift and system vac increases the vac motor has enough force to open the door once again. *1 - causes could be a cracked or disconnected vac line somewhere, leaking vac motor diaphragm, etc. from Randy & Valerie __ __ \ \/ / \__/olvo 1993 960 Estate Randy, Sorry, my mistake. This is 1994 940 with 4 cylinder. Could this switch or flap caused by the momentem of the acceleration movement that push this switch from blowing to top than to bottom? Where could this be? Any picture? Thank you. > >OK, after another day of work by the mechanics, this is still our problem: > > [quoted text clipped - 32 lines] > \__/olvo > 1993 960 Estate >Randy, > [quoted text clipped - 3 lines] >movement that push this switch from blowing to top than to bottom? Where >could this be? Any picture? I really don't know for sure. Maybe one of the gurus who knows this car can say for sure. I would definitely start with the tip I gave about checking the vac under real-time conditions- connect a vac gauge to a line under the dash and drive and see what is really happening. from Randy & Valerie __ __ \ \/ / \__/olvo 1993 960 Estate The vacuum motor is faulty & needs to be replaced this is the one with 2 lines going in to it under the dash on the left side of the climate unit will post part # Monday night Glenn  Signature"*-344-*Never Forgotten" Is for the New York City Firemen who lost their lives on September 11,2001. The official count is 343, but there was also a volunteer who lost his life aiding in the initial rescue efforts. And I will never forget them as long as I live, nor should any American. "Mow Green" > OK, after another day of work by the mechanics, this is still our problem: > [quoted text clipped - 11 lines] > The fan seems to blow at same speed. > The air-conditioner on or off has the same problem. OK, thank you. Is this part of the entire control unit? Is this on the center top row on the dashboard with 3 turn knobs (fan speed, blower up/bottom direction, and temperature) and two push buttons (recirculation, air condition) ? Is it possible for a picture of this? Where can I buy used or refurbish or replacement unit? Any way to repair it? > The vacuum motor is faulty & needs to be replaced this is the one with 2 > lines going in to it under the dash on the left side of the climate unit [quoted text clipped - 25 lines] > > The fan seems to blow at same speed. > > The air-conditioner on or off has the same problem. The part is not very expensive but the labor to change it is up there if you are a do it yourself person it is an all day job if you are not a do it yourself person then shop around between the Volvo dealer & your local Volvo specialist to see has the better price both time & hourly rate Glenn Signature"*-344-*Never Forgotten" Is for the New York City Firemen who lost their lives on September 11,2001. The official count is 343, but there was also a volunteer who lost his life aiding in the initial rescue efforts. And I will never forget them as long as I live, nor should any American. "Mow Green" > OK, thank you. Is this part of the entire control unit? > Is this on the center top row on the dashboard with 3 turn knobs (fan speed, [quoted text clipped - 38 lines] > > > The fan seems to blow at same speed. > > > The air-conditioner on or off has the same problem. >OK, thank you. Is this part of the entire control unit? >Is this on the center top row on the dashboard with 3 turn knobs (fan speed, [quoted text clipped - 4 lines] > >Where can I buy used or refurbish or replacement unit? Any way to repair it? The info ytou are looking for is here: http://tinyurl.com/25z3b Specifically, I think that this will/may answer the questions: http://tinyurl.com/3fdau __ __ Randy & \ \/ /alerie's \__/olvo '93 960 Estate OK, further repair report. But saddly still same problem. The mechanic replaced the entire dashboard control unit. This is the control unit on the center top row dashboard console. This control unit has 3 large turn knobs (fan speed, blower direction, temperature) and two smaller push buttons for recirculation & air-conditioning. Behind the middle large turn knobs for blower direction, its actually a white plastic square box with vacuum nozzles. I assume that's how Volvo uses vacuum to control the blower direction to top or bottom. After this control unit is replaced, the air blow works normal inside the garage when the car is stationary. However, when the car is moving at least 25mph or faster and during acceleration, the fan blowing slows down and switch from blowing from the top to the bottom of the car. The blower switch back to top when stop accelerating. We are unable to find any vacuum leak anywhere. >OK, further repair report. But saddly still same problem. > [quoted text clipped - 14 lines] > >We are unable to find any vacuum leak anywhere. The first place to check is the double acting vac motor located at the driver's foot well, up against the right side of the well, on the large black climate control box/whatever. Remove the cover there and you will see it. It has two vac lines going to it. One side is probably leaking. This can easily be checked with a mighty-vac tester. This unit is famous for its failure rate. One side will hold vac and the other side will not. The replacement involves either removing the dash and disassembling the temp control box (whatever it is called) or just cutting a hole i the face of the box and then putting a plastic patch over the hols when done. __ __ Randy & \ \/ /alerie's \__/olvo '93 960 Estate Is this inside the car or outside engine compartment? > The first place to check is the double acting vac motor located at the > driver's foot well, up against the right side of the well, on the [quoted text clipped - 10 lines] > \__/olvo > '93 960 Estate >Is this inside the car or outside engine compartment? Sit in the driver's seat. With your right foot, kick sideways to the right. If that panel were not there, you would pretty much have kicked the device of which I spoke. Once you have the panel off, it will be immediately obvious which one it is. A vacuum tester will be a quick way to check it. Mine was so bad that you could hear the air being sucked through it with the panel on and the motor running. __ __ Randy & \ \/ /alerie's \__/olvo '93 960 Estate OK, thank you for all of your advise and help. I post the pictures of the driver's side foot well. You can click to enlarge the photos. http://www.angelfire.com/pro/young707/volvo.html There are two air ducts outlets at this location. There is a set of wires go into the firewall. There are nothing else. You can see the center console enclosure plastic side and the carpet on top of the transmission. May be you can tell me where to find this vacuum control device. Thank you. A. J. Please post more detail of this vacuum motor? Thank you very much. > The vacuum motor is faulty & needs to be replaced this is the one with 2 > lines going in to it under the dash on the left side of the climate unit > will post part # Monday night > Glenn > > -- The vacuum bellows which controls the push/pull blend door is faulty it needs to be replaced it is the only vacuum bellows with 2 fittings on it usually on the drivers side of the climate unit Glenn Signature"*-344-*Never Forgotten" Is for the New York City Firemen who lost their lives on September 11,2001. The official count is 343, but there was also a volunteer who lost his life aiding in the initial rescue efforts. And I will never forget them as long as I live, nor should any American. "Mow Green" > Additional finding: > [quoted text clipped - 20 lines] > > The vacuum advance seems to be working correctly. > > Can you tell me what is the problem? Thank you. This is 1994 Volvo 940 with single push button on/off air conditioner. There is no temperature or climate control. > The vacuum bellows which controls the push/pull blend door is faulty it > needs to be replaced it is the only vacuum bellows with 2 fittings on it > usually on the drivers side of the climate unit > Glenn You may have a 93 control unit. They are no longer avilable. There was a problem with them. > My 1994 Volvo 940, 4 cylinder (not turbo) air conditioner is acting > strangely. Normally, I set the air condition fan blowing from the front on [quoted text clipped - 6 lines] > The vacuum advance seems to be working correctly. > Can you tell me what is the problem? Thank you. What is the name of control unit? Is this on the center top row on the dashboard with 3 turn knobs (fan speed, blower up/bottom direction, and temperature) and two push buttons (recirculation, air condition) ? Where can I buy used or refurbish or replacement unit? How much does it costs? Any way to repair it? Thank you. > You may have a 93 control unit. They are no longer avilable. There was a > problem with them. |
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