Interior heating saga

[MotoMan]

Hi all,

I have searched the archives and posts to see if anyone has had the same problem as i have, and have tried the solutions provided but to no avail.

i have a 525 94 m50 and the heating system is screwed. The centre vents - one blows hot the other luke warm. All the top vents blow hot air and the foot well vents hot aswell. I have tried to renew the Heater valve as well as the "sword" control unit without any success. the results remain exactly the same.

Are the any other components that i am unaware of that may be causing this problem ? I have admittedly used 2 other "2nd hand" control units and i am unaware of their working staus, but i doubt all 3 would have exactly the same failure ??????

Please can someone assist me.....

Thanks in advance

Victor

[Kalevera]

It's a long shot, but maybe the potentiometer in the center vent is messed up? I'd think that, if it went, it would affect the entire thing, but who knows.

Edit: as you're getting hot air out of both the left and right sides, the heater valve shouldn't be the issue. Could be a stepper motor/flap, or perhaps some other blockage is preventing hot air from getting by. Is the rate of flow consistent?

best, whit

[grave77]

well I have this problem in my car ... but from the drivers side. when I put the AC on I get warmer air with less air flow ... other sides work fine. I opend up the dash from underneeth.. and there I found many things to be checked.
stepper motors ... sword unit. and there is one box behind the sword on the carpit. it has 4 plugs 2 left and 2 right. this has the whole heating / cooling brain. u need to check this out. if ur doing it on ur own u need to spend 4 hours at least. once u opend the dash. switch the heater on before u put the ignition key in. dunk down and switch the key on to ACC ... and look at the flappers and its arms if u see one having a hard time turning then this is ur one ... if everything seem ok .. then start with the electronic controller in the back of the heating unit. hope this would help.

[MotoMan]

Thanx lowell and Grave,

The rate of flow is exactly the same from all sides of the top (front window) vents and footwell vents. The temp is exactly the same at max heat.

Lowell i considered the centre potentiometer but it "seems" to be "fine". I turned it to max heat with the manual dials set to max heat and it reacted as expected. When i turned all to cool, the centre vents went cool almost immediately but left the upper and lower vents bellowing hot air. Dunno...mabe i should exchange it.

Grave i was unaware of the 2nd unit you mentioned. I will look out for it. I have exchanged the sword twice but have not seen it. Is it further back or toward the dash area ? With regards, the stepper motors - my system has manual slides for flap control....so i guess that ruels that out. Perhaps the 2nd unit you spoke of ??

Thanks again for all the assistance, this one is a real pain in the a## driving with the heater on max at both the footwell and screen....

[Kalevera]

They're not actually manual flaps, although the presence of "sliders" gives that impression. The famous "buzzing noise from my dash at shutdown" comes from the actuators moving them around.

I'm sorry - I was a bit confused earlier. I thought cold air was coming from everything but HALF of the center vent when you switched it from heat to a/c, in which case something should be blocking the center vent somewhere -- it's a long shot, of course, and highly unlikely.

best, whit

[grave77]

by the way i remembered one thing u need to check ... that does the valves get a signal? both should have no ground voltage ( 0 ) when the heater is turned on. and both should have the ground when its off. u also need to cheack this out. it might be a missed connection to the valve thats causing u all this pain.