Volvo 940 electric fan almost stops at acceleration

I have a 1994 Volvo 940 with 4 cyclinder engine (no turbo) with auto
transmission.

For the last years or so, the electric fan blower virtually stops when I
accelerate the car. Actually the harder I accelerate, the slower the fan
blows. That is when I just have the fan on, or heater or air-conditioning.
But, as soon as I leave my foot off the gas padel, the fan will blow strong
again.

All other electrical equipment seems to work.
Can you tell me what is the problem? Thank you.

 

Two things

1 Are you sure the fan is slowing down? It could be that the air flow is
getting diverted when the engine vacuum changes on acceleration.

2 Could be worn out brushes in the motor plus worn bearing that lets the shaft
shift on acceleration. The green machine acted up a lot whrn the brushes wore
out. Moving the wiring made it come back on for a while. The fan was not bad
from Car Quest auto parts. Just make sure you get the correct one. There are
two kinds.

Brickboard can probibly help if it is a vacuum problem.

Al

 

Thank you for your reply.

I test by setting the fan on high. Before and after I accelerate, I can
hear and feel when the blower immediately slowing virtually to a halt.

The fan blow large of volume air blasting at idle or coasting without
acceleration. So I think the fan is OK. Don't you agree?

I do not think the electricity is drained at accelerate because the radio
plays OK before and after acceleration.

Thanks for your suggestions.

 

Does it have ECC or manual AC. Let me know and I'll check my factory
training manuals.I made a lot of notes when I took the AC class.

 

Manual AC.
A button will turn the air-conditioning on and off.
Fan has to be turn to select 1 to 5 settings.

I do not know what is ECC. I assume its one of those economic control of
setting certain temperature and it regulated the air-conditioner.

 

That could be a vacuum leak. Check the two hoses that connect to the
throttle body. Most likley it is a bad diafraghm in one of the vent flaps.

 

Thank you Rod.
I assume you mean rubber hose? Can you tell me exactly what it looks like
and where it is located? Any way to easily test there is a vacuum lead?

I do not have the Volvo manual. Is there any of such diagram and picture
online that I can guessestimate what and where it is?

Thank you.

 

There's a vacuum servo behind the driver's side kick panel that is
connected to two vacuum sources. The diaphragm in that servo is leaking.
This is a common problem.

Bob

 

I didn,t get to check your post last night. You have have regular ACC,
Manual Climate Control. ECC is Electronic Climate Control. I will check
which hose it is. They are color coded so you shouldn't have a problem
finding it.To check if it is leaking down crimp the hose with a pair of
needle nose pliers and switch the controls to other vent positions and check
if they function correctly.

 

Got My training manual. Remove the glove box to access the valve bank. It
has 7 colored hoses connected to it. Pull off one hose at a time. Put your
finger over the nipple on the valve bank.If you don't feel any suction on
all of them the problem is back toward the engine. May be a crack in the
vacuum tank. If you have suction on some but not all it is the valve bank.
Suction on all means a vacuum line or servo.In that case pull them off one
at a time again.Hold your finger over the nipple and change the vent
controls. If the air flow switches to the selected vent, that line or servo
is the problem.The vent shutter is on the left side of the heater box. It is
the one closest to the shifter and the only one with a secondary hose back
to the valve bank. That is the red hose. the primary suspect. Here are the
color codes:
coolant valve gray
recirulation shutter orange
vent shutter red
bi-level shutter brown
defrost shutter blue
floorshutter yellow
Hope that helps A.J.Y.

 

Rod, thank you for your help and suggestions:
I have posted the engine compartment pictures of the car at
http://www.angelfire.com/pro/hollywoodhouse/Volvo.html

Is that round thing is vacuum hose - black rubber hose comes out at the end,
in the front middle of the picture F?

I am unable to remove the glove box to get to the valve bank.
Can you tell me how to remove the glove box?
Thank you veyr much.

 

That is a vacuum hose but it is the fuel regulator.If your brakes feel fine
don't worry about the hoses under the hood. The glove box has two screws
located under the covers on each side of the glove box. Pry them off with a
flat blade scwerdriver. The screws are TORX so you need a TORX wrench to
remove them. I think it is a number 25. Then remove the two nuts on the
bottom of the glove box. That takes a 10 Millimiter socket. Pull down on the
box and pull it out. Then you can access the valve block.