1986 735i air only blowing out of defrost

[amzsprmn]

I have a 1986 735i. When I try to depress the control panel buttons for the a/c it lights up then goes out as soon as I let go of the button. Also, air only blows out of the defrost.
A second issue. I have no power assist for the brakes and the power steering. My legs and arms are getting a major work out. Please help. Thank you in advance for your advice.

[Bear]

Sounds like the fluid for the brakes/power steering is empty. did you check the reservoir for fluid? Also the do brakes run off of fluid boost from the power steering pump and if so is the pump good or is the belt still in place? I am a 750 ('88) guy so my system may be different as I have a brake servo in the engine compartment and if that is leaking the fluid goes away and I lose all boost (no pneumatics on this car for boost).

[Bear]

Here are a couple of websites you may find helpful:
http://www/nmia.com/~dgnrg/page_2.htm

http://bmwe32.masscom.net

The first is Don Gale's 7 series site and the second Johan and Sean's site, both are excellent sources of information for our cars.

[Bear]

make that first site:
http://www.nmia.com/~dgnrg/page_2.htm/

[Bear]

Maybe http://www.nmia.com/~dgnrg/page_2.htm

[lincolnmaster80]

Do you mean that the A/C will not come on when you push in and take your finger off? Probably looking at a worn LHKM.

Or will only come on when the driver and passenger blower setting is set to feet/dash defrost? This is usually normal in order for the cold air to come out of the vents. You may have a blown fuse too, so don't forget to neglect those.

http://bmwe32.masscom.net/johan/e_box/fuse_box.html

[amzsprmn]

it is full of fluid and the belt is intact

[Bear]

Air only blowing out of defrost could be the HVAC control or the Air Distribution Motors (steppers). There are 9 (I believe steppers) that control the position of the flapper valves for all of the vents. These steppers have mounts that on the early cars were prone to fail and jam and therefore no air comes out of certain vents. Look at he MASSCOM website for more on the steppers as well as AC.

[Bear]

How old is the PS filter, have you tried evacuating the reservoir and cleaning it out as well as replacing the filter?

[amzsprmn]

I did take it to jiffy lube. If they put the wrong fluid in the reservoir could that cause this problem?
Where would I locate the p/s filter?

[Bear]

I doubt that the wrong fluid would cause a increase in pressure, there has been much discussion about the wrong fluid causing deterioration of the seals in the system but I have never seen any proof. there should be a plastic ring around the top of the reservoir that tells you what the correct fluid is (PENTOSIN 7 or ATF). If the belt is tight and the reservoir is full I would first, replace the filter in the reservoir and see what that does. If the brake pedal is hard on the first braking (each time) I would suspect the bomb is bad. There is a accumulator under the ABS controller that is shaped like a bomb (the one Wiley Coyote carried in the Road Runner cartoon). Thi8s is filled with nitrogen and has a hermetic seal at the top, it is an emergency braking backup and if you lose brake pressure the seal brakes and the nitrogen flows giving you emergency braking assist. If that is bad you will feel like you have no brakes in an panic stop, the pedal will be ultra firm and you will think no brakes, if you release the pedal and reapply the brakes will feel normal. This bomb is replaceable and yu can do it, requires removing two support bracket screws and the hex nut atop the bomb. You may lose a bit if fluid as you take the bomb off (I did not) and then you put in a new bomb, make sure fluid reservoir is full and the brake system is normal. As to the PS, replace the filter, check the fluid as to type and see what happens. If that does not work, I would suspect the PS pump as you have a pump supplying pressure to the steering and the brakes (no pneumatic booster on these cars).

[amzsprmn]

thank you bear. I will try these.

[Bear]

I am a firm believer in staring at the simplest fix and I would first, replace that filter in the PS reservoir, if she is clogged (I do not know how old yours is) then the pressure downstream will be reduced and of course more effort to steer and brake. Our son and his wife have a 1988 735i and I have driven it several times and the steering and braking effort are not abnormal.

[amzsprmn]

I have evacuated the ps pump and changed the filter. I have filled it with new fluid and still does not work. Now what do i do

[Bear]

If the issue is still with the PS and brakes, then I would replace the PS pump. Do you have a vendor list, if not email me at [email protected] and I will supply a list.